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Spring Boot(七)：Mybatis 多数据源最简解决方案

说起多数据源，一般都来解决那些问题呢，主从模式或者业务比较复杂需要连接不同的分库来支持业务。我们遇到的情况是后者，网上找了很多，大都是根据 Jpa 来做多数据源解决方案，要不就是老的 Spring 多数据源解决方案，还有的是利用 Aop 动态切换，感觉有点小复杂，其实我只是想找一个简单的多数据支持而已，折腾了两个小时整理出来，供大家参考。

废话不多说直接上代码吧

我们以 Mybatis Xml 版本为例，给大家展示如何如何配置多数据源。

配置文件

Pom 包就不贴了比较简单该依赖的就依赖，主要是数据库这边的配置：

mybatis.config-location=classpath:mybatis/mybatis-config.xml

spring.datasource.test1.jdbc-url=jdbc:mysql://localhost:3306/test1?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.test1.username=root
spring.datasource.test1.password=root
spring.datasource.test1.driver-class-name=com.mysql.cj.jdbc.Driver


spring.datasource.test2.jdbc-url=jdbc:mysql://localhost:3306/test2?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.test2.username=root
spring.datasource.test2.password=root
spring.datasource.test2.driver-class-name=com.mysql.cj.jdbc.Driver

一个 test1 库和一个 test2 库，其中 test1 位主库，在使用的过程中必须指定主库，不然会报错。

数据源配置

@Configuration
@MapperScan(basePackages = "com.neo.mapper.test1", sqlSessionTemplateRef  = "test1SqlSessionTemplate")
public class DataSource1Config {

<span class="hljs-meta">@Bean(name = "test1DataSource")</span>
<span class="hljs-meta">@ConfigurationProperties(prefix = "spring.datasource.test1")</span>
<span class="hljs-meta">@Primary</span>
<span class="hljs-keyword">public</span> DataSource <span class="hljs-title function_">testDataSource</span><span class="hljs-params">()</span> {
    <span class="hljs-keyword">return</span> DataSourceBuilder.create().build();
}

<span class="hljs-meta">@Bean(name = "test1SqlSessionFactory")</span>
<span class="hljs-meta">@Primary</span>
<span class="hljs-keyword">public</span> SqlSessionFactory <span class="hljs-title function_">testSqlSessionFactory</span><span class="hljs-params">(<span class="hljs-meta">@Qualifier("test1DataSource")</span> DataSource dataSource)</span> <span class="hljs-keyword">throws</span> Exception {
    <span class="hljs-type">SqlSessionFactoryBean</span> <span class="hljs-variable">bean</span> <span class="hljs-operator">=</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">SqlSessionFactoryBean</span>();
    bean.setDataSource(dataSource);
    bean.setMapperLocations(<span class="hljs-keyword">new</span> <span class="hljs-title class_">PathMatchingResourcePatternResolver</span>().getResources(<span class="hljs-string">"classpath:mybatis/mapper/test1/*.xml"</span>));
    <span class="hljs-keyword">return</span> bean.getObject();
}

<span class="hljs-meta">@Bean(name = "test1TransactionManager")</span>
<span class="hljs-meta">@Primary</span>
<span class="hljs-keyword">public</span> DataSourceTransactionManager <span class="hljs-title function_">testTransactionManager</span><span class="hljs-params">(<span class="hljs-meta">@Qualifier("test1DataSource")</span> DataSource dataSource)</span> {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">DataSourceTransactionManager</span>(dataSource);
}

<span class="hljs-meta">@Bean(name = "test1SqlSessionTemplate")</span>
<span class="hljs-meta">@Primary</span>
<span class="hljs-keyword">public</span> SqlSessionTemplate <span class="hljs-title function_">testSqlSessionTemplate</span><span class="hljs-params">(<span class="hljs-meta">@Qualifier("test1SqlSessionFactory")</span> SqlSessionFactory sqlSessionFactory)</span> <span class="hljs-keyword">throws</span> Exception {
    <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> <span class="hljs-title class_">SqlSessionTemplate</span>(sqlSessionFactory);
}



}

最关键的地方就是这块了，一层一层注入, 首先创建 DataSource，然后创建 SqlSessionFactory 再创建事务，最后包装到 SqlSessionTemplate 中。其中需要指定分库的 mapper 文件地址，以及分库 dao 层代码

@MapperScan(basePackages = "com.neo.mapper.test1", sqlSessionTemplateRef  = "test1SqlSessionTemplate")

这块的注解就是指明了扫描 dao 层，并且给 dao 层注入指定的 SqlSessionTemplate。所有@Bean都需要按照命名指定正确。

dao 层和 xml 层

dao 层和 xml 需要按照库来分在不同的目录，比如：test1 库 dao 层在 com.neo.mapper.test1 包下，test2 库在com.neo.mapper.test2

public interface User1Mapper {
	List<UserEntity> getAll();
	UserEntity getOne(Long id);
	void insert(UserEntity user);
	void update(UserEntity user);
	void delete(Long id);
}

xml 层

<mapper namespace="com.neo.mapper.test1.User1Mapper" >
    <resultMap id="BaseResultMap" type="com.neo.model.User" >
        <id column="id" property="id" jdbcType="BIGINT" />
        <result column="userName" property="userName" jdbcType="VARCHAR" />
        <result column="passWord" property="passWord" jdbcType="VARCHAR" />
        <result column="user_sex" property="userSex" javaType="com.neo.enums.UserSexEnum"/>
        <result column="nick_name" property="nickName" jdbcType="VARCHAR" />
    </resultMap>

<span class="hljs-tag">&lt;<span class="hljs-name">sql</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"Base_Column_List"</span> &gt;</span>
    id, userName, passWord, user_sex, nick_name
<span class="hljs-tag">&lt;/<span class="hljs-name">sql</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">select</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"getAll"</span> <span class="hljs-attr">resultMap</span>=<span class="hljs-string">"BaseResultMap"</span>  &gt;</span>
   SELECT 
   <span class="hljs-tag">&lt;<span class="hljs-name">include</span> <span class="hljs-attr">refid</span>=<span class="hljs-string">"Base_Column_List"</span> /&gt;</span>
 FROM users
<span class="hljs-tag">&lt;/<span class="hljs-name">select</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">select</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"getOne"</span> <span class="hljs-attr">parameterType</span>=<span class="hljs-string">"java.lang.Long"</span> <span class="hljs-attr">resultMap</span>=<span class="hljs-string">"BaseResultMap"</span> &gt;</span>
    SELECT 
   <span class="hljs-tag">&lt;<span class="hljs-name">include</span> <span class="hljs-attr">refid</span>=<span class="hljs-string">"Base_Column_List"</span> /&gt;</span>
 FROM users
 WHERE id = #{id}
<span class="hljs-tag">&lt;/<span class="hljs-name">select</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">insert</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"insert"</span> <span class="hljs-attr">parameterType</span>=<span class="hljs-string">"com.neo.model.User"</span> &gt;</span>
   INSERT INTO 
      users
      (userName,passWord,user_sex) 
    VALUES
      (#{userName}, #{passWord}, #{userSex})
<span class="hljs-tag">&lt;/<span class="hljs-name">insert</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">update</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"update"</span> <span class="hljs-attr">parameterType</span>=<span class="hljs-string">"com.neo.model.User"</span> &gt;</span>
   UPDATE 
      users 
   SET 
    <span class="hljs-tag">&lt;<span class="hljs-name">if</span> <span class="hljs-attr">test</span>=<span class="hljs-string">"userName != null"</span>&gt;</span>userName = #{userName},<span class="hljs-tag">&lt;/<span class="hljs-name">if</span>&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">if</span> <span class="hljs-attr">test</span>=<span class="hljs-string">"passWord != null"</span>&gt;</span>passWord = #{passWord},<span class="hljs-tag">&lt;/<span class="hljs-name">if</span>&gt;</span>
    nick_name = #{nickName}
   WHERE 
      id = #{id}
<span class="hljs-tag">&lt;/<span class="hljs-name">update</span>&gt;</span>

<span class="hljs-tag">&lt;<span class="hljs-name">delete</span> <span class="hljs-attr">id</span>=<span class="hljs-string">"delete"</span> <span class="hljs-attr">parameterType</span>=<span class="hljs-string">"java.lang.Long"</span> &gt;</span>
   DELETE FROM
       users 
   WHERE 
       id =#{id}
<span class="hljs-tag">&lt;/<span class="hljs-name">delete</span>&gt;</span>



</mapper>

测试

测试可以使用 SpringBootTest, 也可以放到 Controller 中，这里只贴 Controller 层的使用

@RestController
public class UserController {

<span class="hljs-meta">@Autowired</span>
<span class="hljs-keyword">private</span> User1Mapper user1Mapper;

<span class="hljs-meta">@Autowired</span>
<span class="hljs-keyword">private</span> User2Mapper user2Mapper;

<span class="hljs-meta">@RequestMapping("/getUsers")</span>
<span class="hljs-keyword">public</span> List&lt;UserEntity&gt; <span class="hljs-title function_">getUsers</span><span class="hljs-params">()</span> {
	List&lt;UserEntity&gt; users=user1Mapper.getAll();
	<span class="hljs-keyword">return</span> users;
}

<span class="hljs-meta">@RequestMapping("/getUser")</span>
<span class="hljs-keyword">public</span> UserEntity <span class="hljs-title function_">getUser</span><span class="hljs-params">(Long id)</span> {
	UserEntity user=user2Mapper.getOne(id);
    <span class="hljs-keyword">return</span> user;
}

<span class="hljs-meta">@RequestMapping("/add")</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title function_">save</span><span class="hljs-params">(UserEntity user)</span> {
    user2Mapper.insert(user);
}

<span class="hljs-meta">@RequestMapping(value="update")</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title function_">update</span><span class="hljs-params">(UserEntity user)</span> {
    user2Mapper.update(user);
}

<span class="hljs-meta">@RequestMapping(value="/delete/{id}")</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title function_">delete</span><span class="hljs-params">(<span class="hljs-meta">@PathVariable("id")</span> Long id)</span> {
    user1Mapper.delete(id);
}



}

Mybatis 注解版本配置多数据源和 Xml 版本基本一致，搭建可以参考文末的示例项目。

文章内容已经升级到 Spring Boot 2.x

示例代码 -github

示例代码 - 码云

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