(整理)MyBatis入门教程（一）
本文转载：
http://www.cnblogs.com/hellokitty1/p/5216025.html#3591383
本人文笔不行，根据上面博客内容引导，自己整理了一些东西
首先给大家推荐几个网页：
http://blog.csdn.net/isea533/article/category/2092001 没事看看 - MyBatis 工具：www.mybatis.tk
http://www.mybatis.org/mybatis-3/zh/getting-started.html 入门
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。
一、理解什么是 MyBatis？
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。 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）MyBATIS 目前提供了三种语言实现的版本，包括：Java、.NET 以及 Ruby。（我主要学习 java，就讲 java 的使用）
2）它提供的持久层框架包括 SQL Maps 和 Data Access Objects（DAO）。
3）mybatis 与 hibernate 的对比？
mybatis 提供一种“半自动化”的 ORM 实现。
这里的“半自动化”，是相对 Hibernate 等提供了全面的数据库封装机制的“全自动化”ORM 实现而言，“全自动”ORM 实现了 POJO 和数据库表之间的映射，以及 SQL 的自动生成和执行。
而 mybatis 的着力点，则在于 POJO 与 SQL 之间的映射关系。
二、简单例子（快速入门）
1）首先建立项目 java web
2）配置 mybatis 所需的 jar 包,pom.xml
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.2.8</version>
</dependency>
<!-- logback start -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.7</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.1.3</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-access</artifactId>
<version>1.1.3</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.3</version>
</dependency>
<!-- logback end -->
3) 创建数据库数据（mybatis）, 创建表（t_user）
CREATE TABLE `t_user` (
`id` int(11) NOT NULL auto_increment,
`username` varchar(20) default NULL,
`password` varchar(20) default NULL,
`account` double(10,2) default NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=utf8
4）mysql 驱动配置文件 mysql.properties
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/mybatis
jdbc.username=admin
jdbc.password=123456
5）添加 mybatis 配置文件 mybatis.cfg.xml
<?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><!-- 引入外部配置文件 -->
<properties resource="mysql.properties"></properties><!-- 为 JAVA Bean 起类别名 -->
<typeAliases >
<!-- 别名方式 1，一个一个的配置 type 中放置的是类的全路径，alias 中放置的是类别名
<typeAliase type="com.cy.mybatis.beans.UserBean" alias="UserBean"/> -->
<!-- 别名方式 2，自动扫描，将 JAVA 类的类名作为类的类别名 -->
<package name="com.wenyin.mybatis.beans"/>
</typeAliases>
<!-- 配置 mybatis 运行环境 -->
<environments default="cybatis">
<environment id="cybatis">
<!-- type="JDBC" 代表使用 JDBC 的提交和回滚来管理事务 -->
<transactionManager type="JDBC" /><span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> mybatis提供了3种数据源类型，分别是：POOLED,UNPOOLED,JNDI </span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> POOLED 表示支持JDBC数据源连接池 </span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> UNPOOLED 表示不支持数据源连接池 </span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> JNDI 表示支持外部数据源连接池 </span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 0, 255, 1)"><</span><span style="color: rgba(128, 0, 0, 1)">dataSource </span><span style="color: rgba(255, 0, 0, 1)">type</span><span style="color: rgba(0, 0, 255, 1)">="POOLED"</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</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)">="driver"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.driver}"</span> <span style="color: rgba(0, 0, 255, 1)">/></span> <span style="color: rgba(0, 0, 255, 1)"><</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="url"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.url}"</span> <span style="color: rgba(0, 0, 255, 1)">/></span> <span style="color: rgba(0, 0, 255, 1)"><</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)">="${jdbc.username}"</span> <span style="color: rgba(0, 0, 255, 1)">/></span> <span style="color: rgba(0, 0, 255, 1)"><</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.password}"</span> <span style="color: rgba(0, 0, 255, 1)">/></span> <span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">dataSource</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">environment</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">environments</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</span><span style="color: rgba(128, 0, 0, 1)">mappers</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> 告知映射文件方式1，一个一个的配置 <mapper resource="com/cy/mybatis/mapper/UserMapper.xml"/></span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 128, 0, 1)"><!--</span><span style="color: rgba(0, 128, 0, 1)"> 告知映射文件方式2，自动扫描包内的Mapper接口与配置文件 </span><span style="color: rgba(0, 128, 0, 1)">--></span> <span style="color: rgba(0, 0, 255, 1)"><</span><span style="color: rgba(128, 0, 0, 1)">package </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="com/wenyin/mybatis/mapper"</span><span style="color: rgba(0, 0, 255, 1)">/></span> <span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">mappers</span><span style="color: rgba(0, 0, 255, 1)">></span></configuration>
6) 创建对应的实体对象
7）创建方法接口 UserMapper.java 和定义操作 t_user 表的 sql 映射文件 UserMapper.xml
提供简单的增删改查数据信息。
package com.wenyin.mybatis.mapper; import java.util.List; import com.wenyin.mybatis.beans.UserBean; public interface UserMapper { /** * 新增用戶 * @param user * @return * @throws Exception */ public int insertUser(UserBean user) throws Exception; /** * 修改用戶 * @param user * @param id * @return * @throws Exception */ public int updateUser (UserBean user,int id) throws Exception; /** * 刪除用戶 * @param id * @return * @throws Exception */ public int deleteUser(int id) throws Exception; /** * 根据 id 查询用户信息 * @param id * @return * @throws Exception */ public UserBean selectUserById(int id) throws Exception; /** * 查询所有的用户信息 * @return * @throws Exception */ public List<UserBean> selectAllUser() throws Exception; }
UserMapper.xml
<?xml version="1.0" encoding="UTF-8"?> <!-- 不写会报错 --> <!DOCTYPE mapper PUBLIC "-//mybatis.org/DTD Mapper 3.0" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.wenyin.mybatis.mapper.UserMapper"> <!-- 自定义返回结果集 --> <resultMap id="userMap" type="UserBean"> <id property="id" column="id" javaType="java.lang.Integer"></id> <result property="username" column="username" javaType="java.lang.String"></result> <result property="password" column="password" javaType="java.lang.String"></result> <result property="account" column="account" javaType="java.lang.Double"></result> </resultMap> <!-- 在各种标签中的 id 属性必须和接口中的方法名相同 ， id 属性值必须是唯一的，不能够重复使用。parameterType 属性指明查询时使用的参数类型， resultType 属性指明查询返回的结果集类型--> <!-- useGeneratedKeys：（ 仅 对 insert 有 用 ） 这 会 告 诉 MyBatis 使 用 JDBC 的 getGeneratedKeys 方法来取出由数据（比如：像 MySQL 和 SQLServer 这样的数据库管理系统的自动递增字段）内部生成的主键。默认值： false。
oracle 不支持应该设置成 useGeneratedKeys="false" 不然会报错
--> <!--keyProperty： （仅对 insert 有用）标记一个属性， MyBatis 会通过 getGeneratedKeys 或者通过 insert 语句的 selectKey 子元素设置它的值。默认：不设置。 --> <!--#{} 中的内容，为占位符，当参数为某个 JavaBean 时，表示放置该 Bean 对象的属性值 --><span style="color: rgba(0, 0, 255, 1)"><</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)"> useGeneratedKeys</span><span style="color: rgba(0, 0, 255, 1)">="true"</span><span style="color: rgba(255, 0, 0, 1)"> keyProperty</span><span style="color: rgba(0, 0, 255, 1)">="id"</span><span style="color: rgba(0, 0, 255, 1)">></span><span style="color: rgba(0, 0, 0, 1)"> insert into t_user (username,password,account) values (#{username},#{password},#{account}) </span><span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">insert</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</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(0, 0, 255, 1)">></span><span style="color: rgba(0, 0, 0, 1)"> update t_user set username=#{username},password=#{password},account=#{account} where id=#{id} </span><span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">update</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</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)">></span><span style="color: rgba(0, 0, 0, 1)"> delete from t_user where id=#{id} </span><span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">delete</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</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)">="selectUserById"</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)">="userMap"</span><span style="color: rgba(0, 0, 255, 1)">></span><span style="color: rgba(0, 0, 0, 1)"> select * from t_user where id=#{id} </span><span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">></span> <span style="color: rgba(0, 0, 255, 1)"><</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)">="selectAllUser"</span><span style="color: rgba(255, 0, 0, 1)"> resultMap</span><span style="color: rgba(0, 0, 255, 1)">="userMap"</span><span style="color: rgba(0, 0, 255, 1)">></span><span style="color: rgba(0, 0, 0, 1)"> select * from t_user </span><span style="color: rgba(0, 0, 255, 1)"></</span><span style="color: rgba(128, 0, 0, 1)">select</span><span style="color: rgba(0, 0, 255, 1)">></span></mapper>
这时需要为 mybatis.cfg.xml 里注册 UserMapper.xml 文件。
参照第5）步骤
8）需要建立一个工具类文件
package com.wenyin.mybatis.tools;import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class DBTools {
public static SqlSessionFactory sessionFactory;</span><span style="color: rgba(0, 0, 255, 1)">static</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)"> { </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">使用MyBatis提供的Resources类加载mybatis的配置文件</span> Reader reader = Resources.getResourceAsReader("mybatis.cfg.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)">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, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) { e.printStackTrace(); } } </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</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, 0, 1)"> SqlSession getSession(){ </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> sessionFactory.openSession(); }}
9）写个测试UserService.java
package com.wenyin.mybatis.service;import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import com.wenyin.mybatis.beans.UserBean;
import com.wenyin.mybatis.mapper.UserMapper;
import com.wenyin.mybatis.tools.DBTools;public class UserService {
</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">static</span> Logger logger = LoggerFactory.getLogger(UserService.<span style="color: rgba(0, 0, 255, 1)">class</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) { insertUser(); </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">deleteUser(1); </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">selectUserById(2); </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">selectAllUser();</span>}
</span><span style="color: rgba(0, 128, 0, 1)">/**</span><span style="color: rgba(0, 128, 0, 1)"> * 新增用户 </span><span style="color: rgba(0, 128, 0, 1)">*/</span> <span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">boolean</span><span style="color: rgba(0, 0, 0, 1)"> insertUser(){ SqlSession session </span>=<span style="color: rgba(0, 0, 0, 1)"> DBTools.getSession(); UserMapper mapper </span>= session.getMapper(UserMapper.<span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">); UserBean user </span>= <span style="color: rgba(0, 0, 255, 1)">new</span> UserBean("test01", "123456", 7000.0<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)"> { </span><span style="color: rgba(0, 0, 255, 1)">int</span> index=<span style="color: rgba(0, 0, 0, 1)">mapper.insertUser(user); </span><span style="color: rgba(0, 0, 255, 1)">boolean</span> bool=index>0?<span style="color: rgba(0, 0, 255, 1)">true</span>:<span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; logger.error(</span>"新增用户user对象:{},操作状态:{}",<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> Object[]{user,bool}); session.commit(); </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> bool; } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) { e.printStackTrace(); session.rollback(); </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; }finally{<br> session.close();<br> } } </span><span style="color: rgba(0, 128, 0, 1)">/**</span><span style="color: rgba(0, 128, 0, 1)"> * 删除用户 * </span><span style="color: rgba(128, 128, 128, 1)">@param</span><span style="color: rgba(0, 128, 0, 1)"> id 用户ID </span><span style="color: rgba(0, 128, 0, 1)">*/</span> <span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">boolean</span> deleteUser(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id){ SqlSession session</span>=<span style="color: rgba(0, 0, 0, 1)">DBTools.getSession(); UserMapper mapper</span>=session.getMapper(UserMapper.<span style="color: rgba(0, 0, 255, 1)">class</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)"> { </span><span style="color: rgba(0, 0, 255, 1)">int</span> index=<span style="color: rgba(0, 0, 0, 1)">mapper.deleteUser(id); </span><span style="color: rgba(0, 0, 255, 1)">boolean</span> bool=index>0?<span style="color: rgba(0, 0, 255, 1)">true</span>:<span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; logger.debug(</span>"根据用户id:{},操作状态{}",<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> Object[]{id,bool}); session.commit(); </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> bool; } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) { e.printStackTrace(); session.rollback(); </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">; }finally{<br> session.close();<br> } } </span><span style="color: rgba(0, 128, 0, 1)">/**</span><span style="color: rgba(0, 128, 0, 1)"> * 根据id查询用户 * </span><span style="color: rgba(128, 128, 128, 1)">@param</span><span style="color: rgba(0, 128, 0, 1)"> id </span><span style="color: rgba(0, 128, 0, 1)">*/</span> <span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">static</span> <span style="color: rgba(0, 0, 255, 1)">void</span> selectUserById(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id){ SqlSession session</span>=<span style="color: rgba(0, 0, 0, 1)">DBTools.getSession(); UserMapper mapper</span>=session.getMapper(UserMapper.<span style="color: rgba(0, 0, 255, 1)">class</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)"> { UserBean user</span>=<span style="color: rgba(0, 0, 0, 1)"> mapper.selectUserById(id); logger.debug(</span>"根据用户Id:{},查询用户信息:{}",<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> Object[]{id,user}); session.commit(); } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) { e.printStackTrace(); session.rollback(); }finally{<br> session.close();<br> } } </span><span style="color: rgba(0, 128, 0, 1)">/**</span><span style="color: rgba(0, 128, 0, 1)"> * 查询所有的用户 </span><span style="color: rgba(0, 128, 0, 1)">*/</span> <span style="color: rgba(0, 0, 255, 1)">private</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)"> selectAllUser(){ SqlSession session</span>=<span style="color: rgba(0, 0, 0, 1)">DBTools.getSession(); UserMapper mapper</span>=session.getMapper(UserMapper.<span style="color: rgba(0, 0, 255, 1)">class</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)"> { List</span><UserBean> user=<span style="color: rgba(0, 0, 0, 1)">mapper.selectAllUser(); logger.debug(</span>"获取所用的用户:{}"<span style="color: rgba(0, 0, 0, 1)">,user); session.commit(); } </span><span style="color: rgba(0, 0, 255, 1)">catch</span><span style="color: rgba(0, 0, 0, 1)"> (Exception e) { e.printStackTrace(); session.rollback(); }finally{<br> session.close();<br> } }}
新增运行结果：
如果返回 Map<String,Object>
<select id="getMap" resultType="java.util.HashMap" parameterType="int">
select username,id from
t_user where
id=#{id}
</select>
返回 List<Map<String,Object>>
<select id="getList" resultType="java.util.HashMap" >
SELECT * FROM t_user
</select>