springboot+mybatis如何实现多数据源呢?

下文笔者讲述SpringBoot结合mybatis实现多数据源的方法分享,如下所示

多数据源的用途

多数据源用途:
    1.主从模式应用
	2.分库应用(某些业务分库,导致需要多库运行)

多数据源的实现思路

多数据源实现思路:
     1.配置文件中加入多数据源
	 2.编写config文件添加多数据源

例

配置文件添加

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

//test1库和test2库
//test1为主库
//默认情况下,代码访问主库

数据源配置

@Configuration
@MapperScan(basePackages = "com.java265.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);
    }

}

注意事项:
    创建DataSource
     然后创建SqlSessionFactory
	   再创建事务
    最后包装到SqlSessionTemplate中
	
	例:
	指定分库的mapper文件地址，以及分库dao层代码
@MapperScan(basePackages = "com.java265.mapper.test1", sqlSessionTemplateRef  = "test1SqlSessionTemplate") 

dao层和xml层

dao层和xml需要按照库来分在不同的目录
  如：test1库dao层在com.java265.mapper.test1包下，test2库在com.java265.mapper.test1

例：

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.java265.mapper.test1.User1Mapper" >
    <resultMap id="BaseResultMap" type="com.java265.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.java265.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.java265.entity.UserEntity" >
       INSERT INTO 
               users
               (userName,passWord,user_sex) 
           VALUES
               (#{userName}, #{passWord}, #{userSex})
    </insert>
    
    <update id="update" parameterType="com.java265.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

@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);
    }
    
}