"　　MyBatis 本是 apache 的一个开源项目 iBatis, 2010 年这个项目由 apache software foundation 迁移到了 google code，并且改名为 MyBatis 。2013 年 11 月迁移到 Github。iBATIS 一词来源于“internet ...."

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MyBatis使用总结+整合Spring

　　MyBatis 本是 apache 的一个开源项目 iBatis, 2010 年这个项目由 apache software foundation 迁移到了 google code，并且改名为 MyBatis 。2013 年 11 月迁移到 Github。iBATIS 一词来源于“internet”和“abatis”的组合，是一个基于 Java 的持久层框架。

　　MyBatis 是支持普通 SQL 查询，存储过程和高级映射的优秀持久层框架。MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及对结果集的检索封装。MyBatis 可以使用简单的 XML 或注解用于配置和原始映射，将接口和 Java 的 POJO（Plain Old Java Objects，普通的 Java 对象）映射成数据库中的记录。

1 第一个 MyBatis 程序

　　首先需要加入需要的 jar 包，构建 Spring 环境请参考：Spring 学习之第一个 hello world 程序。这里我们需要加入 mybatis 包和 MySQL 驱动包，使用 IDEA 环境来开发程序，最后工程加入的包如下图所示：

　　然后需要在 test 数据库中新建测试表 user，sql 语句如下所示：

create table users (
    id int primary key auto_increment,
    name varchar(20),
    age int
);
insert into users (name, age) values('Tom', 12);
insert into users (name, age) values('Jack', 11);

1.1 定义表对应的实体类

public class User {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String name;
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> User() { }

</span><span style="color: rgba(0, 0, 255, 1)">public</span> User(<span style="color: rgba(0, 0, 255, 1)">int</span> id, String name, <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getId() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getName() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setName(String name) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getAge() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> age;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setAge(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age;
}

@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String toString() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> "User{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", age=" + age +
            '}'<span style="color: rgba(0, 0, 0, 1)">;
}

}

1.2 定义 MyBatista 的 mybatisConfig.xml 配置文件和 user 表的 sql 映射文件 userMapper.xml

mybatisConfig.xml 文件，该文件是在 src 目录下新建的。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<!-- development: 开发环境 work: 工作模式 -->
<environment id="development">
<transactionManager type="JDBC" />
<!-- 数据库连接方式 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://192.168.1.150/test" />
<property name="username" value="root" />
<property name="password" value="123456" />
</dataSource>
</environment>
</environments>
<!-- 注册表映射文件 -->
<mappers>
<mapper resource="com/mybatis/userMapper.xml"/>
</mappers>
</configuration>

userMapper.xml 文件，该配置文件在 com.mybatis 包下，user 表对应的实体类 User 也在 com.mybatis 包下。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.userMapper">
<!-- 根据 id 查询一个 User 对象 -->
<select id="getUser" parameterType="int" resultType="com.mybatis.User">
select * from users where id=#{id}
</select>
<select id="getUserAll" resultType="com.mybatis.User">
select * from users
</select>
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 插入一个User对象 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">insert </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="insertUser"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    insert into users (name, age) value(#{name}, #{age})
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">insert</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 删除一个User对象 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">delete </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="deleteUser"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="int"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    delete from users where id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">delete</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 更新一个User对象</span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">update </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="updateUser"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    update users set name=#{name}, age=#{age} where id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">update</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</mapper>

测试代码如下：

public class mybaitstest {
SqlSessionFactory sessionFactory </span>= <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
SqlSession sqlSession </span>= <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;

{
    String resource </span>= "mybatisConfig.xml"<span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 加载mybatis的配置文件（它也加载关联的映射文件）</span>
    Reader reader = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        reader </span>=<span style="color: rgba(0, 0, 0, 1)"> Resources.getResourceAsReader(resource);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (IOException e) {
        e.printStackTrace();
    }
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 构建sqlSession的工厂</span>
    sessionFactory = <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> SqlSessionFactoryBuilder().build(reader);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 创建能执行映射文件中sql的sqlSession，默认是手动提交事务的，使用自动提交的话加上参数 true</span>
    sqlSession = sessionFactory.openSession(<span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testSelectUser() {
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 映射sql的标识字符串</span>
    String statement = "com.mybatis.userMapper" + ".getUser"<span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 执行查询返回一个唯一user对象的sql</span>
    User user = sqlSession.selectOne(statement, 1<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(user);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testSelectAll() {
    List</span>&lt;User&gt; users = sqlSession.selectList("com.mybatis.userMapper.getUserAll"<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(users);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testInsertUser(User user) {
    </span><span style="color: rgba(0, 0, 255, 1)">int</span> insert = sqlSession.insert("com.mybatis.userMapper.insertUser"<span style="color: rgba(0, 0, 0, 1)">, user);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 如果不是自动提交的话，需要使用 sqlSession。commit()</span>

        System.out.println(insert);
}
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> testDeleteUser(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    </span><span style="color: rgba(0, 0, 255, 1)">int</span> delete = sqlSession.delete("com.mybatis.userMapper.deleteUser"<span style="color: rgba(0, 0, 0, 1)">, id);
    System.out.println(delete);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testUpdateUser(User user) {
    </span><span style="color: rgba(0, 0, 255, 1)">int</span> update = sqlSession.update("com.mybatis.userMapper.updateUser"<span style="color: rgba(0, 0, 0, 1)">, user);
    System.out.println(update);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">void</span> main(String[] args) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> IOException {

    </span><span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> mybaitstest().testSelectUser();
}

}

最后输出结果为：

2 基于注解的方式使用 MyBatis

　　基于注解的方式使用 MyBatis，首先定义对应表的 sql 映射接口。

public interface IUserMapper {
@Insert(</span>"insert into users (name, age) value(#{name}, #{age})"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> add(User user);

@Delete(</span>"delete from users where id=#{id}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span> deleteById(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id);

@Update(</span>"update users set name=#{name}, age=#{age} where id=#{id}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> update(User user);

@Select(</span>"select * from users where id=#{id}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> User getById(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id);

@Select(</span>"select * from users"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> getAll();

}

　　然后在 mybatisConfig.xml 配置文件中注册该接口：

<!-- 注册表映射文件 -->
<mappers>
    <mapper class="com.mybatis.IUserMapper"/>
</mappers>

测试示例：

/**
 * 使用注解测试的方法
 */
public void test() {
    IUserMapper userMapper = sqlSession.getMapper(IUserMapper.class);
User user </span>= userMapper.getById(1<span style="color: rgba(0, 0, 0, 1)">);
System.out.println(user);

}

3 如何简化配置操作

　　以上两个程序示例都是直接在配置文件中写连接数据库的信息，其实还可以专门把数据库连接信息写到一个 db.proteries 文件中，然后由配置文件来读取该 db.properies 文件信息。db.proteries 文件内容如下：

user=root
password=123456
driverClass=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql://192.168.1.150/test

　　然后在 mybatisConfig.xml 配置文件中将数据库环境信息更改为如下所示：

<properties resource="db.properties"/>
<environments default="development">
<!-- development: 开发环境 work: 工作模式 -->
<environment id="development">
<transactionManager type="JDBC" />
<!-- 数据库连接方式 -->
<dataSource type="POOLED">
<property name="driver" value="${driverClass}" />
<property name="url" value="${jdbcUrl}" />
<property name="username" value="${user}" />
<property name="password" value="${password}" />
</dataSource>
</environment>
</environments>

　　配置表对应的 sql 映射文件时，可以使用别名来简化配置，在 mybatisConfig.xml 中添加如下配置，在 userMapper 中 parameterType 就可以配置为 "_User"。

<typeAliases>
    <typeAlias type="com.mybatis.User" alias="_User"/>
</typeAliases>

4 字段名与实体类属性名不匹配的冲突

　　新建表和数据，在 test 数据库中执行以下 SQL 语句：

create table orders (
    order_id int primary key auto_increment,
    order_no varchar(20),
    order_price float
);
insert into orders (order_no, order_price) values('aaa', 12);
insert into orders (order_no, order_price) values('bbb', 13);
insert into orders (order_no, order_price) values('ccc', 14);

　　创建对应表的类：

public class Order {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> i;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String no;
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">float</span><span style="color: rgba(0, 0, 0, 1)"> price;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> Order() { }

</span><span style="color: rgba(0, 0, 255, 1)">public</span> Order(<span style="color: rgba(0, 0, 255, 1)">int</span> i, String no, <span style="color: rgba(0, 0, 255, 1)">float</span><span style="color: rgba(0, 0, 0, 1)"> price) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.i =<span style="color: rgba(0, 0, 0, 1)"> i;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.no =<span style="color: rgba(0, 0, 0, 1)"> no;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.price =<span style="color: rgba(0, 0, 0, 1)"> price;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getI() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> i;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setI(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> i) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.i =<span style="color: rgba(0, 0, 0, 1)"> i;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getNo() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> no;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setNo(String no) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.no =<span style="color: rgba(0, 0, 0, 1)"> no;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">float</span><span style="color: rgba(0, 0, 0, 1)"> getPrice() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> price;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setPrice(<span style="color: rgba(0, 0, 255, 1)">float</span><span style="color: rgba(0, 0, 0, 1)"> price) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.price =<span style="color: rgba(0, 0, 0, 1)"> price;
}

}

View Code

　　mybaitsConfig.xml 配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
&lt;properties resource="db.properties"/&gt;

&lt;typeAliases&gt;
    &lt;typeAlias type="com.mybatis.Order" alias="Order"/&gt;
&lt;/typeAliases&gt;

&lt;environments <span style="color: rgba(0, 0, 255, 1)">default</span>="development"&gt;
    &lt;!-- development:开发环境 work:工作模式 --&gt;
    &lt;environment id="development"&gt;
        &lt;transactionManager type="JDBC" /&gt;
        &lt;!-- 数据库连接方式 --&gt;
        &lt;dataSource type="POOLED"&gt;
            &lt;property name="driver" value="${driverClass}" /&gt;
            &lt;property name="url" value="${jdbcUrl}" /&gt;
            &lt;property name="username" value="${user}" /&gt;
            &lt;property name="password" value="${password}" /&gt;
        &lt;/dataSource&gt;
    &lt;/environment&gt;
&lt;/environments&gt;

&lt;!-- 注册表映射文件 --&gt;
&lt;mappers&gt;
    &lt;mapper resource="com/mybatis/orderMapper.xml"/&gt;
&lt;/mappers&gt;

</configuration>

　　接下来配置 orderMapper.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.orderMapper">
&lt;!-- 根据id查询一个Order对象 --&gt;
&lt;select id="getOrder" parameterType="int" resultType="Order"&gt;<span style="color: rgba(0, 0, 0, 1)">
  SELECT order_id id, order_no no, order_price price FROM orders WHERE order_id</span>=<span style="color: rgba(0, 0, 0, 1)">#{id}
</span>&lt;/select&gt;

&lt;!-- 这种解决字段与属性冲突方式较常用 --&gt;
&lt;select id="getOrder2" parameterType="int" resultType="Order" resultMap="getOrder2Map"&gt;<span style="color: rgba(0, 0, 0, 1)">
    SELECT </span>* FROM orders WHERE order_id=<span style="color: rgba(0, 0, 0, 1)">#{id}
</span>&lt;/select&gt;
&lt;!--<span style="color: rgba(0, 0, 0, 1)">
    resultMap 封装映射关系
        id    专门针对主键
        result 针对一般字段
</span>--&gt;
&lt;resultMap id="getOrder2Map" type="Order"&gt;
    &lt;id property="id" column="order_id"/&gt;
    &lt;result property="no" column="order_price"/&gt;
    &lt;result property="price" column="order_price"/&gt;
&lt;/resultMap&gt;

</mapper>

View Code

测试用例：

public class MyBaitsMain {
    SqlSessionFactory sessionFactory = null;
    SqlSession sqlSession = null;
{
    String resource </span>= "mybatisConfig.xml"<span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 加载mybatis的配置文件（它也加载关联的映射文件）</span>
    Reader reader = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        reader </span>=<span style="color: rgba(0, 0, 0, 1)"> Resources.getResourceAsReader(resource);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (IOException e) {
        e.printStackTrace();
    }
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 构建sqlSession的工厂</span>
    sessionFactory = <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> SqlSessionFactoryBuilder().build(reader);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 创建能执行映射文件中sql的sqlSession，默认是手动提交事务的，使用自动提交的话加上参数 true</span>
    sqlSession = sessionFactory.openSession(<span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> main(String[] args) {
    String statement </span>= "com.mybatis.orderMapper.getOrder"<span style="color: rgba(0, 0, 0, 1)">;
    String statement2 </span>= "com.mybatis.orderMapper.getOrder2"<span style="color: rgba(0, 0, 0, 1)">;

    Order order </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement, 2<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(order);
    order </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement2, 2<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(order);
}

}

输出结果为：

5 实现关联表查询

5.1 一对一关联

　　这里实现班级 id 查询班级信息，班级信息中包括老师信息。首先创建表结构：

CREATE TABLE teacher(
    t_id INT PRIMARY KEY AUTO_INCREMENT, 
    t_name VARCHAR(20)
);
CREATE TABLE class(
    c_id INT PRIMARY KEY AUTO_INCREMENT, 
    c_name VARCHAR(20), 
    teacher_id INT
);
ALTER TABLE class ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id);    
INSERT INTO teacher(t_name) VALUES('LS1');
INSERT INTO teacher(t_name) VALUES('LS2');
INSERT INTO class(c_name, teacher_id) VALUES('bj_a', 1);
INSERT INTO class(c_name, teacher_id) VALUES('bj_b', 2);

View Code

　　定义表对应的实体类：

public class Teacher {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String name;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> Teacher() {
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> Teacher(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id, String name) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getId() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getName() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setName(String name) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String toString() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> "Teacher{" +
            "id=" + id +
            ", name='" + name + '\'' +
            '}'<span style="color: rgba(0, 0, 0, 1)">;
}

}

Teacher 类

public class Classes {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String name;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> Teacher teacher;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> Classes() {
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> Classes(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id, String name, Teacher teacher) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.teacher =<span style="color: rgba(0, 0, 0, 1)"> teacher;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getId() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> Teacher getTeacher() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> teacher;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setTeacher(Teacher teacher) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.teacher =<span style="color: rgba(0, 0, 0, 1)"> teacher;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getName() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setName(String name) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String toString() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> "Classes{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", teacher=" + teacher +
            '}'<span style="color: rgba(0, 0, 0, 1)">;
}

}

Classes 类

　　定义 sql 映射文件，需要在 mybatisConfig.xml 中注册该表映射文件。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.classesMapper">
&lt;!-- 根据班级id查询班级信息（包括老师信息） --&gt;
&lt;select id="getClasses" parameterType="int" resultMap="ClassesMap"&gt;<span style="color: rgba(0, 0, 0, 1)">
    SELECT </span>* FROM <span style="color: rgba(0, 0, 255, 1)">class</span> c, teacher t WHERE c.teacher_id = t.t_id and c.c_id =<span style="color: rgba(0, 0, 0, 1)"> #{id}
</span>&lt;/select&gt;
&lt;!-- 联表查询 --&gt;
&lt;resultMap id="ClassesMap" type="com.mybatis.Classes"&gt;
    &lt;id property="id" column="c_id"/&gt;
    &lt;result property="name" column="c_name"/&gt;
    &lt;association property="teacher" column="teacher_id" javaType="com.mybatis.Teacher"&gt;
        &lt;id property="id" column="t_id"/&gt;
        &lt;result property="name" column="t_name"/&gt;
    &lt;/association&gt;
&lt;/resultMap&gt;

&lt;!-- 嵌套查询 --&gt;
&lt;select id="getClasses2" parameterType="int" resultMap="ClassesMap2"&gt;<span style="color: rgba(0, 0, 0, 1)">
    SELECT </span>* FROM <span style="color: rgba(0, 0, 255, 1)">class</span> WHERE c_id=<span style="color: rgba(0, 0, 0, 1)">#{id}
</span>&lt;/select&gt;
&lt;select id="getTeacher" parameterType="int" resultType="com.mybatis.Teacher"&gt;<span style="color: rgba(0, 0, 0, 1)">
    SELECT t_id id, t_name  FROM teacher WHERE t_id</span>=<span style="color: rgba(0, 0, 0, 1)">#{id}
</span>&lt;/select&gt;
&lt;resultMap id="ClassesMap2" type="com.mybatis.Classes"&gt;
    &lt;id property="id" column="c_id"/&gt;
    &lt;result property="name" column="c_name"/&gt;
    &lt;association property="teacher" column="teacher_id" select="getTeacher"&gt;
    &lt;/association&gt;
&lt;/resultMap&gt;

</mapper>

classesMapper.xml 文件

测试类：

public class MyBaitsMain {
    SqlSessionFactory sessionFactory = null;
    SqlSession sqlSession = null;
{
    String resource </span>= "mybatisConfig.xml"<span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 加载mybatis的配置文件（它也加载关联的映射文件）</span>
    Reader reader = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        reader </span>=<span style="color: rgba(0, 0, 0, 1)"> Resources.getResourceAsReader(resource);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (IOException e) {
        e.printStackTrace();
    }
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 构建sqlSession的工厂</span>
    sessionFactory = <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> SqlSessionFactoryBuilder().build(reader);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 创建能执行映射文件中sql的sqlSession，默认是手动提交事务的，使用自动提交的话加上参数 true</span>
    sqlSession = sessionFactory.openSession(<span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> main(String[] args) {

    String statement </span>= "com.mybatis.classesMapper.getClasses"<span style="color: rgba(0, 0, 0, 1)">;
    String statement2 </span>= "com.mybatis.classesMapper.getClasses2"<span style="color: rgba(0, 0, 0, 1)">;

    Classes classes </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement, 1<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(classes);
    classes </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement2, 1<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(classes);
}

}

MyBatisMain 测试类

输出结果：

5.2 一对多关联

　　这里实现班级 id 查询班级信息，班级信息中包括老师信息和学生信息。首先创建表结构：

CREATE TABLE student(
    s_id INT PRIMARY KEY AUTO_INCREMENT, 
    s_name VARCHAR(20), 
    class_id INT
);
INSERT INTO student(s_name, class_id) VALUES('xs_A', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_B', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_C', 1);
INSERT INTO student(s_name, class_id) VALUES('xs_D', 2);
INSERT INTO student(s_name, class_id) VALUES('xs_E', 2);
INSERT INTO student(s_name, class_id) VALUES('xs_F', 2);

　　定义表对应的实体类：

public class Student {
private </span><span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id;
private String name;

</span><span style="color: rgba(0, 0, 255, 1)">public</span> Student(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id, String name) {
    this.id </span><span style="color: rgba(128, 128, 128, 1)">=</span><span style="color: rgba(0, 0, 0, 1)"> id;
    this.name </span><span style="color: rgba(128, 128, 128, 1)">=</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> Student() {
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getId() {

    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> void setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    this.id </span><span style="color: rgba(128, 128, 128, 1)">=</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getName() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> void setName(String name) {
    this.name </span><span style="color: rgba(128, 128, 128, 1)">=</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 128, 0, 1)">@Override</span>
<span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String toString() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> "Student{" <span style="color: rgba(128, 128, 128, 1)">+</span><span style="color: rgba(0, 0, 0, 1)">
            "id</span><span style="color: rgba(128, 128, 128, 1)">=</span>" <span style="color: rgba(128, 128, 128, 1)">+</span> id <span style="color: rgba(128, 128, 128, 1)">+</span><span style="color: rgba(0, 0, 0, 1)">
            ", name</span><span style="color: rgba(128, 128, 128, 1)">=</span><span style="color: rgba(255, 0, 0, 1)">'</span><span style="color: rgba(255, 0, 0, 1)">" + name + </span><span style="color: rgba(255, 0, 0, 1)">'</span>\<span style="color: rgba(255, 0, 0, 1)">''</span> <span style="color: rgba(128, 128, 128, 1)">+</span>
            <span style="color: rgba(255, 0, 0, 1)">'</span><span style="color: rgba(255, 0, 0, 1)">}</span><span style="color: rgba(255, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">;
}

}

Student 类

　　定义 sql 映射文件，需要在 mybatisConfig.xml 中注册该表映射文件。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.mybatis.classesMapper2">
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getClasses"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="int"</span><span style="color: rgba(255, 0, 0, 1)"> resultMap</span><span style="color: rgba(0, 0, 255, 1)">="ClassesMap"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT * FROM class c, student s, teacher t WHERE c.c_id=s.class_id AND c.c_id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">resultMap </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="ClassesMap"</span><span style="color: rgba(255, 0, 0, 1)"> type</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Classes"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">id </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="id"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="c_id"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">result </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="name"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="c_name"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">association </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="teacher"</span><span style="color: rgba(255, 0, 0, 1)"> javaType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Teacher"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
        <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">id </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="id"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="t_id"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
        <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">result </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="name"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="t_name"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">association</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">
        collection: 做一对多关联查询的
            ofType: 指定集合中元素对象的类型
    </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">collection </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="students"</span><span style="color: rgba(255, 0, 0, 1)"> ofType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Student"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
        <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">id </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="id"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="s_id"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
        <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">result </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="name"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="s_name"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">collection</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">resultMap</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 第二种方式 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getClasses2"</span><span style="color: rgba(255, 0, 0, 1)"> resultMap</span><span style="color: rgba(0, 0, 255, 1)">="ClassesMap2"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT * FROM class WHERE c_id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getTeacher"</span><span style="color: rgba(255, 0, 0, 1)"> resultType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Teacher"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT t_id id, t_name name FROM teacher WHERE  t_id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getStudent"</span><span style="color: rgba(255, 0, 0, 1)"> resultType</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Student"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT s_id id, s_name name FROM student WHERE  class_id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">resultMap </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="ClassesMap2"</span><span style="color: rgba(255, 0, 0, 1)"> type</span><span style="color: rgba(0, 0, 255, 1)">="com.mybatis.Classes"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">id </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="id"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="c_id"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">result </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="name"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="c_name"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">association </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="teacher"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="teacher_id"</span><span style="color: rgba(255, 0, 0, 1)"> select</span><span style="color: rgba(0, 0, 255, 1)">="getTeacher"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">association</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">collection </span><span style="color: rgba(255, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">="students"</span><span style="color: rgba(255, 0, 0, 1)"> column</span><span style="color: rgba(0, 0, 255, 1)">="c_id"</span><span style="color: rgba(255, 0, 0, 1)"> select</span><span style="color: rgba(0, 0, 255, 1)">="getStudent"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">collection</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">resultMap</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</mapper>

classesMapper2.xml 文件

　　测试类：

public class MyBaitsMain {
    SqlSessionFactory sessionFactory = null;
    SqlSession sqlSession = null;
{
    String resource </span>= "mybatisConfig.xml"<span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 加载mybatis的配置文件（它也加载关联的映射文件）</span>
    Reader reader = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)"> {
        reader </span>=<span style="color: rgba(0, 0, 0, 1)"> Resources.getResourceAsReader(resource);
    } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (IOException e) {
        e.printStackTrace();
    }
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 构建sqlSession的工厂</span>
    sessionFactory = <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> SqlSessionFactoryBuilder().build(reader);
    </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)"> 创建能执行映射文件中sql的sqlSession，默认是手动提交事务的，使用自动提交的话加上参数 true</span>
    sqlSession = sessionFactory.openSession(<span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> main(String[] args) {

    String statement </span>= "com.mybatis.classesMapper2.getClasses"<span style="color: rgba(0, 0, 0, 1)">;
    String statement2 </span>= "com.mybatis.classesMapper2.getClasses2"<span style="color: rgba(0, 0, 0, 1)">;

    Classes classes </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement, 1<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(classes);
    classes </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> MyBaitsMain().sqlSession.selectOne(statement2, 1<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(classes);
}

}

MyBaitsMain 测试类

输出结果：

6 MyBatis 的缓存

正如大多数持久层框架一样，MyBatis 同样提供了一级缓存和二级缓存的支持

一级缓存: 基于 PerpetualCache 的 HashMap 本地缓存，其存储作用域为 Session，当 Session flush 或 close 之后，该 Session 中的所有 Cache 就将清空。
二级缓存与一级缓存其机制相同，默认也是采用 PerpetualCache，HashMap 存储，不同在于其存储作用域为 Mapper(Namespace)，并且可自定义存储源，如 Ehcache。
对于缓存数据更新机制，当某一个作用域 (一级缓存 Session/ 二级缓存 Namespaces) 的进行了 C/U/D 操作后，默认该作用域下所有 select 中的缓存将被 clear。

7 Spring 集成 MyBatis

　　Spring 集成 MyBatis，开发环境为 IDEA，打开 IDEA，新建工程，工程名为 spring-mybatis。注意，这里我选择的是带有 Web 功能的工程，其实在 Spring 集成 MyBatis 示例中并没有用到 Web 功能，这个可选可不选。

1、添加工程所需的 jar 包，比如 MySQL 驱动包、Spring 包、commons-logging 包等，最后添加的包结构图如下：

　　最后整个工程文件如下所示：

2、然后需要在 test 数据库中新建测试表 user，sql 语句如下所示：

create table users (
    id int primary key auto_increment,
    name varchar(20),
    age int
);
insert into users (name, age) values('Tom', 12);
insert into users (name, age) values('Jack', 11);

3、定义表对应的实体类和表操作接口。

package com.luoxn28.test;
public class User {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id;
</span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String name;
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age;

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> User() {
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> User(<span style="color: rgba(0, 0, 255, 1)">int</span> id, String name, <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> User(String name, <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getId() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getName() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setName(String name) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> getAge() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> age;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setAge(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) {
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age;
}

@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String toString() {
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> "User{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", age=" + age +
            '}'<span style="color: rgba(0, 0, 0, 1)">;
}

}

package com.luoxn28.test;
import java.util.List;
public interface UserDao {
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> insert(User user);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> update(User user);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span> delete(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> User getById(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> getAll();

}

4、定义表映射配置文件 userDao.xml 和 MyBatis 配置文件 mybatisConfig.xml。

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.luoxn28.test.UserDao">
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">insert </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="insert"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    INSERT users (name, age) VALUES (#{name}, #{age})
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">insert</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">update </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="update"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    UPDATE users set name=#{name}, age=#{age} where id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">update</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">delete </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="delete"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="int"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    DELETE FROM users where id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">delete</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getById"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="int"</span><span style="color: rgba(255, 0, 0, 1)"> resultType</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT * FROM users WHERE id=#{id}
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">select </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="getAll"</span><span style="color: rgba(255, 0, 0, 1)"> resultType</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test.User"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    SELECT * FROM users
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</mapper>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<mappers>
<mapper resource="com/luoxn28/test/userMapper.xml"/>
</mappers>
</configuration>

5、配置 Spring 的 applicationContext.xml 文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 0.导入外部配置文件 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:property-placeholder </span><span style="color: rgba(255, 0, 0, 1)">location</span><span style="color: rgba(0, 0, 255, 1)">="classpath:db.properties"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 1.配置数据源 DriverManagerDataSource </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="dataSource"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.springframework.jdbc.datasource.DriverManagerDataSource"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="username"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${user}"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${password}"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClassName"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${driverClass}"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="url"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbcUrl}"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 2.mybatis的SqlSession工厂  SqlSessionFactoryBean </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.SqlSessionFactoryBean"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="dataSource"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="dataSource"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="typeAliasesPackage"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span> <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 实体类包名，自动将实体类的简单类名映射成为别名 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="configLocation"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="classpath:mybatisConfig.xml"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 3.mybatis自动扫描加载sql映射文件 MapperScannerConfigurer
&lt;bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer"&gt;
    &lt;property name="basePackage" value="com.luoxn28.test"/&gt;
    &lt;property name="sqlSessionFactory" ref="sqlSessionFactory"/&gt;
&lt;/bean&gt; </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 4.事务管理
&lt;bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"&gt;
    &lt;property name="dataSource" ref="dataSource"/&gt;
&lt;/bean&gt; </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 5.声明式事务 transaction-manager引用定义的事务管理器
&lt;tx:annotation-driven transaction-manager="transactionManager"/&gt; </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="userDao"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.mapper.MapperFactoryBean"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="mapperInterface"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.luoxn28.test.UserDao"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</beans>

6、编写测试类 SMTest

package com.luoxn28.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.testng.annotations.BeforeTest;
import org.testng.annotations.Test;
public class SMTest {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> ApplicationContext context = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;
</span><span style="color: rgba(0, 0, 255, 1)">private</span> UserDao userDao = <span style="color: rgba(0, 0, 255, 1)">null</span><span style="color: rgba(0, 0, 0, 1)">;

@BeforeTest
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> init() {
    context </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> ClassPathXmlApplicationContext("applicationContext.xml"<span style="color: rgba(0, 0, 0, 1)">);
    userDao </span>= (UserDao) context.getBean("userDao"<span style="color: rgba(0, 0, 0, 1)">);
}

@Test
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testInsert() {
    System.out.println(userDao.insert(</span><span style="color: rgba(0, 0, 255, 1)">new</span> User("luoxn28", 23<span style="color: rgba(0, 0, 0, 1)">)));
}

@Test
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testUpdate() {
    System.out.println(userDao.update(</span><span style="color: rgba(0, 0, 255, 1)">new</span> User(10, "luoxn28", 22<span style="color: rgba(0, 0, 0, 1)">)));
}

@Test
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testDelete() {
    System.out.println(userDao.delete(</span>10<span style="color: rgba(0, 0, 0, 1)">));
}

@Test
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> testGetById() {
    System.out.println(userDao.getById(</span>10<span style="color: rgba(0, 0, 0, 1)">));
}

@Test
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> getGetAll() {
    System.out.println(userDao.getAll());
}

}

输出结果（这是测试的是 getGetAll 方法）：

参考资料：

　　1、尚硅谷 -MyBatis 学习视频

　　2、Spring 学习之 AOP 总结帖

MyBatis使用总结+整合Spring

1 第一个 MyBatis 程序

1.1 定义表对应的实体类

1.2 定义 MyBatista 的 mybatisConfig.xml 配置文件和 user 表的 sql 映射文件 userMapper.xml

2 基于注解的方式使用 MyBatis

3 如何简化配置操作

4 字段名与实体类属性名不匹配的冲突

5 实现关联表查询

5.1 一对一关联

5.2 一对多关联

6 MyBatis 的缓存

7 Spring 集成 MyBatis

相关帖子

随便看看

MyBatis使用总结+整合Spring