MyBatis多数据源配置

前言

多数据源，一般都来解决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，过于复杂，当前已Mybatis Xml为例，简单配置。

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 {

    @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,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>

    <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.model.User" >
       INSERT INTO 
          users
          (userName,passWord,user_sex) 
        VALUES
          (#{userName}, #{passWord}, #{userSex})
    </insert>

    <update id="update" parameterType="com.neo.model.User" >
       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);
    }

}