[Java知识库]springboot Mysql 动态切换数据源

主要功能： 实现了主表（mysql1）写数据，从表(mysql2)读数据。

使用工具 https://github.com/baomidou/dynamic-datasource-spring-boot-starter

本人：阿里云环境主从数据库已经部署好，看博客的小伙伴可以直接使用下面的yml 配置文件。

想自己部署的参考这篇博客本人 https://zhaideyou.blog.csdn.net/article/details/123821990

创建项目: 引入依赖

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.1.4</version>
    </dependency>
    
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
        <version>3.3.1</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

spring:
  datasource:
    dynamic:
      primary: master #设置默认的数据源或者数据源组,默认值即为master
      strict: false #设置严格模式,默认false不启动. 启动后在未匹配到指定数据源时候会抛出异常,不启动则使用默认数据源.
      datasource:
        master:
          url: jdbc:mysql://39.103.170.254:33061/javaboydb
          username: root
          password: 123
        slave:
          url: jdbc:mysql://39.103.170.254:33062/javaboydb
          username: root
          password: 123

@Data
public class User {
    private int id;
    private String username;
}

@Mapper
public interface UserMapper {
    @Insert( "insert into javaboydb.user(username) values (#{username})" )
    long addUser(String username);
    @Select( "select * from javaboydb.user" )
    List<User> getAllUser();
}

public interface UserService {

    long addUser(String username);

    List<User> getAllUser();
}

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;

    @Override
    @DS( "master" )
    public long addUser(String username) {
        return userMapper.addUser( username );
    }

    @Override
    @DS( "slave" )
    public List<User> getAllUser() {
        return userMapper.getAllUser();
    }
}

测试：

@Autowired
private UserService userService;
@Test
void testAddUser(){
    System.out.println( userService.addUser( "赵六" ) );
}

@Test
void getAllUser(){
    List<User> userList = userService.getAllUser();
    userList.forEach( System.out::println );
}

使用mybatis-plus 测试

添加依赖,

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.5.0</version>
</dependency>

@Mapper
public interface UserMapper2 extends BaseMapper<User> {
}

public interface UserService2  extends IService<User> {


}

@Service
public class UserServiceImpl2 extends ServiceImpl<UserMapper2, User> implements UserService2 {

    @Override
    @DS( "slave" )
    public List<User> list() {
        System.out.println("使用读数据库");
        return super.list();
    }

    @Override
    @DS( "master" )
    public boolean save(User entity) {
        return super.save( entity );
    }
}

测试

/**
 * Mybatis-plus 测试
 *
 */
@Test
@DisplayName( "使用mybatis-plus 测试" )
void testAddUser2(){

    userService2.save(new User( (int) Math.random(),"j江南一点雨是大佬"));
}

/**
 * Mybatis-plus 测试
 *
 */
@Test
@DisplayName( "使用mybatis-plus 测试" )
void saveUserTest(){
    userService2.list().forEach( System.out::println );
}

自己用数据库连接工具查看数据库。