详解springboot+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。我们项目是后者的模式，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

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

spring.datasource.test1.driverClassName = com.mysql.jdbc.Driver
spring.datasource.test1.url = jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8
spring.datasource.test1.username = root
spring.datasource.test1.password = root

spring.datasource.test2.driverClassName = com.mysql.jdbc.Driver
spring.datasource.test2.url = jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8
spring.datasource.test2.username = root
spring.datasource.test2.password = root

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

数据源配置

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

  @Bean(name = "test1DataSource")
  @ConfigurationProperties(prefix = "spring.datasource.test1")
  @Primary
  public DataSource testDataSource() {
    return DataSourceBuilder.create().build();
  }

  @Bean(name = "test1SqlSessionFactory")
  @Primary
  public SqlSessionFactory testSqlSessionFactory(@Qualifier("test1DataSource") DataSource dataSource) throws Exception {
    SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
    bean.setDataSource(dataSource);
    bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mybatis/mapper/test1/*.xml"));
    return bean.getObject();
  }

  @Bean(name = "test1TransactionManager")
  @Primary
  public DataSourceTransactionManager testTransactionManager(@Qualifier("test1DataSource") DataSource dataSource) {
    return new DataSourceTransactionManager(dataSource);
  }

  @Bean(name = "test1SqlSessionTemplate")
  @Primary
  public SqlSessionTemplate testSqlSessionTemplate(@Qualifier("test1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
    return new SqlSessionTemplate(sqlSessionFactory);
  }

}

最关键的地方就是这块了，一层一层注入,先创建DataSource，在创建SqlSessionFactory在创建事务，最后包装到SqlSessionTemplate中。其中需要制定分库的mapper文件地址，以及分库到层代码

代码如下:

@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.test1

public interface User1Mapper {

  List<UserEntity> getAll();

  UserEntity getOne(Long id);

  void insert(UserEntity user);

  void update(UserEntity user);

  void delete(Long id);

}

xml层

<?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.neo.mapper.test1.User1Mapper" >
  <resultMap id="BaseResultMap" type="com.neo.entity.UserEntity" >
    <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>

  <sql id="Base_Column_List" >
    id, userName, passWord, user_sex, nick_name
  </sql>

  <select id="getAll" resultMap="BaseResultMap" >
    SELECT
    <include refid="Base_Column_List" />
    FROM users
  </select>

  <select id="getOne" parameterType="java.lang.Long" resultMap="BaseResultMap" >
    SELECT
    <include refid="Base_Column_List" />
    FROM users
    WHERE id = #{id}
  </select>

  <insert id="insert" parameterType="com.neo.entity.UserEntity" >
    INSERT INTO
      users
      (userName,passWord,user_sex)
    VALUES
      (#{userName}, #{passWord}, #{userSex})
  </insert>

  <update id="update" parameterType="com.neo.entity.UserEntity" >
    UPDATE
      users
    SET
    <if test="userName != null">userName = #{userName},</if>
    <if test="passWord != null">passWord = #{passWord},</if>
    nick_name = #{nickName}
    WHERE
      id = #{id}
  </update>

  <delete id="delete" parameterType="java.lang.Long" >
    DELETE FROM
       users
    WHERE
       id =#{id}
  </delete>

</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 {

  @Autowired
  private User1Mapper user1Mapper;

  @Autowired
  private User2Mapper user2Mapper;

  @RequestMapping("/getUsers")
  public List<UserEntity> getUsers() {
    List<UserEntity> users=user1Mapper.getAll();
    return users;
  }

  @RequestMapping("/getUser")
  public UserEntity getUser(Long id) {
    UserEntity user=user2Mapper.getOne(id);
    return user;
  }

  @RequestMapping("/add")
  public void save(UserEntity user) {
    user2Mapper.insert(user);
  }

  @RequestMapping(value="update")
  public void update(UserEntity user) {
    user2Mapper.update(user);
  }

  @RequestMapping(value="/delete/{id}")
  public void delete(@PathVariable("id") Long id) {
    user1Mapper.delete(id);
  }

}

最后源码地址在这里spring-boot-mybatis-mulidatasource

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