日常开发中，我们很少会在一个应用程序中同时使用多个数据源。但是，如果涉及一些数据迁移等应用，可能会涉及将数据从一个库迁移到另外一个库，甚至是不同类型的数据库，比如MySQL到Oracle。

这篇博文，我们不介绍mybatis的基本使用，只介绍基于mybatis配置多数据源的方法。

数据源准备

我这里用了本地MySQL两个库，分别是mybatisone和mybatistwo,mybatisone库中有一张userone表，mybatistwo库中有一张usertwo表，建表sql如下：
userone

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 80021
 Source Host           : localhost:3306
 Source Schema         : mybatisone

 Target Server Type    : MySQL
 Target Server Version : 80021
 File Encoding         : 65001

 Date: 01/10/2020 00:34:29
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for userone
-- ----------------------------
DROP TABLE IF EXISTS `userone`;
CREATE TABLE `userone`  (
  `id` bigint(0) NOT NULL,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of userone
-- ----------------------------
INSERT INTO `userone` VALUES (1, '姓名1');

SET FOREIGN_KEY_CHECKS = 1;

usertwo

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 80021
 Source Host           : localhost:3306
 Source Schema         : mybatistwo

 Target Server Type    : MySQL
 Target Server Version : 80021
 File Encoding         : 65001

 Date: 01/10/2020 00:34:35
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for usertwo
-- ----------------------------
DROP TABLE IF EXISTS `usertwo`;
CREATE TABLE `usertwo`  (
  `id` bigint(0) NOT NULL,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_0900_ai_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of usertwo
-- ----------------------------
INSERT INTO `usertwo` VALUES (1, '姓名2');

SET FOREIGN_KEY_CHECKS = 1;

添加依赖

主要依赖如下

        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.3</version>
        </dependency>
        <!--MySQL驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--druid-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.14</version>
        </dependency>

application.yaml配置文件

yaml文件配置数据源信息以及mybatis的配置信息

spring:
  datasource:
    mybatisone:
      url: jdbc:mysql://localhost:3306/mybatisone?chartset=utf8mb4&serverTimezone=UTC&usessl=false
      username: root
      password: root
      type: com.alibaba.druid.pool.DruidDataSource
    mybatistwo:
      url: jdbc:mysql://localhost:3306/mybatistwo?chartset=utf8mb4&serverTimezone=UTC&usessl=false
      username: root
      password: root
      type: com.alibaba.druid.pool.DruidDataSource
mybatis:
  mapper-locations: classpath*:mapper/*.xml
  type-aliases-package: net.xiangcaowuyu.simplemybatis.entity

配置druid

根据yaml文件提供的DataSource，分别配置对应的两个数据源。
DataSourceConfig.java

/**
 * datasource配置文件
 * @author laughing
 * @date 2020/9/30
 * @site https://www.xiangcaowuyu.net
 */
@Configuration
public class DataSourceConfig {

    /**
     *
     * @return 第一个数据源
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.mybatisone")
    DataSource dataSourceOne(){
        return DruidDataSourceBuilder.create().build();
    }

    /**
     *
     * @return 第二个数据源
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.mybatistwo")
    DataSource dataSourceTwo(){
        return DruidDataSourceBuilder.create().build();
    }

}

配置mybatis数据源

MyBatisConfigOne.java

/**
 * mybatis第一个配置文件
 * @author laughing
 * @date 2020/9/30
 * @site https://www.xiangcaowuyu.net
 */
@Configuration
@MapperScan(basePackages = {"net.xiangcaowuyu.simplemybatis.mapper.one"},sqlSessionFactoryRef = "sqlSessionFactoryOne",sqlSessionTemplateRef = "sqlSessionTemplateOne")
public class MyBatisConfigOne {

    private final Logger logger = LoggerFactory.getLogger(MyBatisConfigOne.class);

    @Resource(name = "dataSourceOne")
    DataSource dataSourceOne;

    @Bean
    SqlSessionFactory sqlSessionFactoryOne() {
        SqlSessionFactory sqlSessionFactory = null;
        try {
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/one/*.xml"));
            sqlSessionFactoryBean.setDataSource(dataSourceOne);
            sqlSessionFactory = sqlSessionFactoryBean.getObject();
        }catch (Exception ex){
            logger.error(ex.getMessage());
        }
        return sqlSessionFactory;
    }

    @Bean
    SqlSessionTemplate sqlSessionTemplateOne(){
        return new SqlSessionTemplate(sqlSessionFactoryOne());
    }
}

MyBatisConfigTwo.java

/**
 * mybatis第二个配置文件
 * @author laughing
 * @date 2020/9/30
 * @site https://www.xiangcaowuyu.net
 */
@Configuration
@MapperScan(basePackages = {"net.xiangcaowuyu.simplemybatis.mapper.two"},sqlSessionFactoryRef = "sqlSessionFactoryTwo",sqlSessionTemplateRef = "sqlSessionTemplateTwo")
public class MyBatisConfigTwo {

    private final Logger logger = LoggerFactory.getLogger(MyBatisConfigTwo.class);

    @Resource(name = "dataSourceTwo")
    DataSource dataSourceTwo;

    @Bean
    SqlSessionFactory sqlSessionFactoryTwo() {
        SqlSessionFactory sqlSessionFactory = null;
        try {
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/two/*.xml"));
            sqlSessionFactoryBean.setDataSource(dataSourceTwo);
            sqlSessionFactory = sqlSessionFactoryBean.getObject();
        }catch (Exception ex){
            logger.error(ex.getMessage());
        }
        return sqlSessionFactory;
    }

    @Bean
    SqlSessionTemplate sqlSessionTemplateTwo(){
        return new SqlSessionTemplate(sqlSessionFactoryTwo());
    }
}

生成mybatis信息

mybatis不是我们要讲解的重点，我这里的信息都是通过Free MyBatis插件自动生成的。不做过多介绍。

增加实体

Userone.java

/**
 * userone
 * @author 
 */
@Data
public class Userone implements Serializable {
    private Long id;

    private String name;

    private static final long serialVersionUID = 1L;
}

Usertwo.java

/**
 * usertwo
 * @author 
 */
@Data
public class Usertwo implements Serializable {
    private Long id;

    private String name;

    private static final long serialVersionUID = 1L;
}

增加mapper

UseroneMapper.java

@Mapper
public interface UseroneMapper {
    int deleteByPrimaryKey(Long id);

    int insert(Userone record);

    int insertSelective(Userone record);

    Userone selectByPrimaryKey(Long id);

    int updateByPrimaryKeySelective(Userone record);

    int updateByPrimaryKey(Userone record);
}

Usertwo.java

/**
 * usertwo
 * @author 
 */
@Data
public class Usertwo implements Serializable {
    private Long id;

    private String name;

    private static final long serialVersionUID = 1L;
}

增加xml

UseroneMapper.xml

<?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="net.xiangcaowuyu.simplemybatis.mapper.one.UseroneMapper">
    <resultMap id="BaseResultMap" type="net.xiangcaowuyu.simplemybatis.entity.Userone">
        <id column="id" jdbcType="BIGINT" property="id"/>
        <result column="name" jdbcType="VARCHAR" property="name"/>
    </resultMap>
    <sql id="Base_Column_List">
    id, `name`
  </sql>
    <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
        select
        <include refid="Base_Column_List"/>
        from userone
        where id = #{id,jdbcType=BIGINT}
    </select>
    <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
    delete from userone
    where id = #{id,jdbcType=BIGINT}
  </delete>
    <insert id="insert" keyColumn="id" keyProperty="id" parameterType="net.xiangcaowuyu.simplemybatis.entity.Userone"
            useGeneratedKeys="true">
    insert into userone (`name`)
    values (#{name,jdbcType=VARCHAR})
  </insert>
    <insert id="insertSelective" keyColumn="id" keyProperty="id"
            parameterType="net.xiangcaowuyu.simplemybatis.entity.Userone" useGeneratedKeys="true">
        insert into userone
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="name != null">
                `name`,
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="name != null">
                #{name,jdbcType=VARCHAR},
            </if>
        </trim>
    </insert>
    <update id="updateByPrimaryKeySelective" parameterType="net.xiangcaowuyu.simplemybatis.entity.Userone">
        update userone
        <set>
            <if test="name != null">
                `name` = #{name,jdbcType=VARCHAR},
            </if>
        </set>
        where id = #{id,jdbcType=BIGINT}
    </update>
    <update id="updateByPrimaryKey" parameterType="net.xiangcaowuyu.simplemybatis.entity.Userone">
    update userone
    set `name` = #{name,jdbcType=VARCHAR}
    where id = #{id,jdbcType=BIGINT}
  </update>
</mapper>

UsertwoMapper.xml

<?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="net.xiangcaowuyu.simplemybatis.mapper.two.UsertwoMapper">
  <resultMap id="BaseResultMap" type="net.xiangcaowuyu.simplemybatis.entity.Usertwo">
    <id column="id" jdbcType="BIGINT" property="id" />
    <result column="name" jdbcType="VARCHAR" property="name" />
  </resultMap>
  <sql id="Base_Column_List">
    id, `name`
  </sql>
  <select id="selectByPrimaryKey" parameterType="java.lang.Long" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from usertwo
    where id = #{id,jdbcType=BIGINT}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Long">
    delete from usertwo
    where id = #{id,jdbcType=BIGINT}
  </delete>
  <insert id="insert" keyColumn="id" keyProperty="id" parameterType="net.xiangcaowuyu.simplemybatis.entity.Usertwo" useGeneratedKeys="true">
    insert into usertwo (`name`)
    values (#{name,jdbcType=VARCHAR})
  </insert>
  <insert id="insertSelective" keyColumn="id" keyProperty="id" parameterType="net.xiangcaowuyu.simplemybatis.entity.Usertwo" useGeneratedKeys="true">
    insert into usertwo
    <trim prefix="(" suffix=")" suffixOverrides=",">
      <if test="name != null">
        `name`,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
      <if test="name != null">
        #{name,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="net.xiangcaowuyu.simplemybatis.entity.Usertwo">
    update usertwo
    <set>
      <if test="name != null">
        `name` = #{name,jdbcType=VARCHAR},
      </if>
    </set>
    where id = #{id,jdbcType=BIGINT}
  </update>
  <update id="updateByPrimaryKey" parameterType="net.xiangcaowuyu.simplemybatis.entity.Usertwo">
    update usertwo
    set `name` = #{name,jdbcType=VARCHAR}
    where id = #{id,jdbcType=BIGINT}
  </update>
</mapper>

配置测试Api

/**
 * @author laughing
 * @date 2020/9/30
 * @site https://www.xiangcaowuyu.net
 */
@RestController
public class MyBatisController {

    @Resource
    UseroneMapper useroneMapper;

    @Resource
    UsertwoMapper usertwoMapper;

    @RequestMapping("/one")
    public Userone userone(){
        return useroneMapper.selectByPrimaryKey(1L);
    }

    @RequestMapping("/two")
    public Usertwo usertwo(){
        return usertwoMapper.selectByPrimaryKey(1L);
    }

}

增加两个Api，分别用于获取数据源1和数据源2的数据。

整体代码结构

里面封装了全局异常，如果不了解的，可以参考 SpringBoot 之 @ControllerAdvice使用场景

代码测试

我们在分别打开两个请求，查看获取的数据

注意事项

在配置数据源时，注意设置mapper的位置，即如下代码：

sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/one/*.xml"));

如果没有设置，可能会提示

Invalid bound statement (not found)