SpringBoot中的DynamicDataSource 如何实现读写分离

SpringBoot中的DynamicDataSource可以通过配置多个数据源来实现读写分离。

首先，在application.yml中配置多个数据源：

spring:
  datasource:
    master:
      url: jdbc:mysql://localhost:3306/master?useUnicode=true&characterEncoding=utf8&useSSL=false
      username: root
      password: 123456
    slave:
      url: jdbc:mysql://localhost:3306/slave?useUnicode=true&characterEncoding=utf8&useSSL=false
      username: root
      password: 123456

然后，在DynamicDataSource类中实现AbstractRoutingDataSource接口，并重写determineCurrentLookupKey方法，根据业务需求动态切换数据源：

public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceKey();
    }

}

最后，在启动类中配置DynamicDataSource，并设置默认数据源：

@SpringBootApplication
public class Application {

    @Bean
    @ConfigurationProperties("spring.datasource.master")
    public DataSource masterDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.slave")
    public DataSource slaveDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    public DynamicDataSource dynamicDataSource() {
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceType.MASTER, masterDataSource());
        targetDataSources.put(DataSourceType.SLAVE, slaveDataSource());

        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        dynamicDataSource.setTargetDataSources(targetDataSources);
        dynamicDataSource.setDefaultTargetDataSource(masterDataSource()); // 默认数据源为master
        return dynamicDataSource;
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

}

在业务代码中，通过设置DataSourceContextHolder中的数据源key，就可以实现动态切换数据源：

@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public void addUser(User user) {
        DataSourceContextHolder.setDataSourceKey(DataSourceType.MASTER);
        userMapper.addUser(user);
    }

    public User getUserById(int id) {
        DataSourceContextHolder.setDataSourceKey(DataSourceType.SLAVE);
        return userMapper.getUserById(id);
    }

}