mybatis plus 多数据源 事物

在 MyBatis Plus 中使用多数据源和事务的步骤如下：

1. 配置多数据源：在 `application.properties` 或 `application.yml` 中配置多个数据源的连接信息，例如：

spring:
  datasource:
    master:
      url: jdbc:mysql://localhost:3306/master_db
      username: root
      password: root123
    slave:
      url: jdbc:mysql://localhost:3306/slave_db
      username: root
      password: root123

2. 创建数据源和事务管理器：在配置类中定义多个数据源，并创建对应的事务管理器，例如：

@Configuration
public class DataSourceConfig {
  
  @Bean(name = "masterDataSource")
  @ConfigurationProperties(prefix = "spring.datasource.master")
  public DataSource masterDataSource() {
    return DataSourceBuilder.create().build();
  }

  @Bean(name = "slaveDataSource")
  @ConfigurationProperties(prefix = "spring.datasource.slave")
  public DataSource slaveDataSource() {
    return DataSourceBuilder.create().build();
  }
  
  @Bean(name = "masterTransactionManager")
  public DataSourceTransactionManager masterTransactionManager(@Qualifier("masterDataSource") DataSource dataSource) {
    return new DataSourceTransactionManager(dataSource);
  }

  @Bean(name = "slaveTransactionManager")
  public DataSourceTransactionManager slaveTransactionManager(@Qualifier("slaveDataSource") DataSource dataSource) {
    return new DataSourceTransactionManager(dataSource);
  }
}

3. 配置 MyBatis Plus 的 SqlSessionFactory 和 MapperScannerConfigurer：在配置类中配置 MyBatis Plus 的 SqlSessionFactory 和 MapperScannerConfigurer，例如：

@Configuration
@MapperScan(basePackages = {"com.example.mapper"})
public class MyBatisConfig {

  @Autowired
  @Qualifier("masterDataSource")
  private DataSource masterDataSource;

  @Autowired
  @Qualifier("slaveDataSource")
  private DataSource slaveDataSource;

  @Autowired
  @Qualifier("masterTransactionManager")
  private DataSourceTransactionManager masterTransactionManager;

  @Autowired
  @Qualifier("slaveTransactionManager")
  private DataSourceTransactionManager slaveTransactionManager;

  @Bean(name = "masterSqlSessionFactory")
  public SqlSessionFactory masterSqlSessionFactory() throws Exception {
    SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
    sessionFactory.setDataSource(masterDataSource);
    return sessionFactory.getObject();
  }

  @Bean(name = "slaveSqlSessionFactory")
  public SqlSessionFactory slaveSqlSessionFactory() throws Exception {
    SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
    sessionFactory.setDataSource(slaveDataSource);
    return sessionFactory.getObject();
  }

  @Bean(name = "masterSqlSessionTemplate")
  public SqlSessionTemplate masterSqlSessionTemplate(@Qualifier("masterSqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
    return new SqlSessionTemplate(sqlSessionFactory);
  }

  @Bean(name = "slaveSqlSessionTemplate")
  public SqlSessionTemplate slaveSqlSessionTemplate(@Qualifier("slaveSqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
    return new SqlSessionTemplate(sqlSessionFactory);
  }

  @Bean
  public MapperScannerConfigurer mapperScannerConfigurer() {
    MapperScannerConfigurer scannerConfigurer = new MapperScannerConfigurer();
    scannerConfigurer.setBasePackage("com.example.mapper");
    return scannerConfigurer;
  }
}

4. 使用注解指定数据源和事务：在需要使用多数据源和事务的地方，使用 `@Transactional` 注解指定数据源和事务管理器，例如：

@Service
public class UserServiceImpl implements UserService {

  @Autowired
  @Qualifier("masterSqlSessionTemplate")
  private SqlSessionTemplate masterSqlSessionTemplate;

  @Autowired
  @Qualifier("slaveSqlSessionTemplate")
  private SqlSessionTemplate slaveSqlSessionTemplate;

  @Override
  @Transactional(transactionManager = "masterTransactionManager")
  public void saveUser(User user) {
    masterSqlSessionTemplate.getMapper(UserMapper.class).save(user);
  }

  @Override
  @Transactional(transactionManager = "slaveTransactionManager")
  public User getUserById(Long userId) {
    return slaveSqlSessionTemplate.getMapper(UserMapper.class).getById(userId);
  }
}

以上步骤可以帮助你在 MyBatis Plus 中实现多数据源和事务的配置与使用。