springboot中mybatis多数据源动态切换实现

谁践踏了优雅 2022-02-05 02:39 295阅读 0赞

在开发中，动态数据源配置还是用的比较多的，比如在多数据源使用方面，又或者是在多个DB之间切换方面。这里给出一个动态数据源的配置方案，两个DB均以mysql为例。

#### 多数据源配置引入 ####

mybatis和mysql在springboot中的引入这里就不在说了，不了解的可以参见[springboot中mysql与mybatis的引入][springboot_mysql_mybatis]。

数据源配置如下：

datasource:
      master:
        type: com.alibaba.druid.pool.DruidDataSource
        jdbc-url: jdbc:mysql://127.0.0.1:3306/sbac_master?autoReconnect=true&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true
        username: root
        password: 1234
        driver-class-name: com.mysql.cj.jdbc.Driver
      log:
        type: com.alibaba.druid.pool.DruidDataSource
        jdbc-url: jdbc:mysql://127.0.0.1:3306/sbac_log?autoReconnect=true&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true
        username: root
        password: 1234
        driver-class-name: com.mysql.cj.jdbc.Driver

mybatis的配置引入如下：

mybatis:
      config-location: classpath:mybatis-config.xml
      mapper-locations: classpath:com/lazycece/sbac/mysql/data/dao/*/mapper/*.xml

这里已然使用的是springboot的自动配置功能配置mybatis信息，只是手动指定了数据源的。如下所示，指定了master和log两个数据源，设置master为默认数据源：

@Configuration
    public class MultiDataSource { 
    
        public static final String MASTER_DATA_SOURCE = "masterDataSource";
        public static final String LOG_DATA_SOURCE = "logDataSource";
    
        @Bean(name = MultiDataSource.MASTER_DATA_SOURCE)
        @ConfigurationProperties(prefix = "datasource.master")
        public DataSource masterDataSource() { 
            return DataSourceBuilder.create().build();
        }
    
        @Bean(name = MultiDataSource.LOG_DATA_SOURCE)
        @ConfigurationProperties(prefix = "datasource.log")
        public DataSource logDataSource() { 
            return DataSourceBuilder.create().build();
        }
    
        @Primary
        @Bean(name = "dynamicDataSource")
        public DynamicDataSource dataSource() { 
            DynamicDataSource dynamicDataSource = new DynamicDataSource();
            dynamicDataSource.setDefaultTargetDataSource(masterDataSource());
            Map<Object, Object> dataSourceMap = new HashMap<>(4);
            dataSourceMap.put(MASTER_DATA_SOURCE, masterDataSource());
            dataSourceMap.put(LOG_DATA_SOURCE, logDataSource());
            dynamicDataSource.setTargetDataSources(dataSourceMap);
            return dynamicDataSource;
        }
    }

#### 动态数据源路由实现 ####

引入了配置信息之后，便是该说如何实现多数据源切换了。我们是通过实现`AbstractRoutingDataSource`类的`determineCurrentLookupKey`方法来实现数据源的动态路由，设置`ThreadLocal`线程保护变量存储数据源key，确保线程间不受影响。

package com.lazycece.sbac.mysql.multi.config;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
    
    /** * @author lazycece */
    public class DynamicDataSource extends AbstractRoutingDataSource { 
        private static final Logger LOGGER = LoggerFactory.getLogger(DynamicDataSource.class);
    
        private static final ThreadLocal<String> DATA_SOURCE_KEY = new ThreadLocal<>();
    
        static void changeDataSource(String dataSourceKey) { 
            DATA_SOURCE_KEY.set(dataSourceKey);
        }
    
        static void clearDataSource() { 
            DATA_SOURCE_KEY.remove();
        }
    
        @Override
        protected Object determineCurrentLookupKey() { 
            String key = DATA_SOURCE_KEY.get();
            LOGGER.info("current data-source is {}", key);
            return key;
        }
    }

随后，便是用AOP的方式来实现数据源的动态切换，注解和切面定义如下：

@Documented
    @Inherited
    @Retention(RetentionPolicy.RUNTIME)
    @Target({ ElementType.METHOD, ElementType.TYPE})
    public @interface DataSource { 
    
        String value();
    }
    
    @Component
    @Aspect
    public class DataSourceConfig { 
    
        @Before("@annotation(dataSource)")
        public void beforeSwitchDataSource(DataSource dataSource) { 
            DynamicDataSource.changeDataSource(dataSource.value());
        }
    
        @After("@annotation(DataSource)")
        public void afterSwitchDataSource() { 
            DynamicDataSource.clearDataSource();
        }
    }

#### 动态数据源切换使用 ####

动态数据源切换只需要在业务中使用`@DataSource`注解来标明需要使用的数据源即可，如下所示（这里只贴出关键代码）：

@Service
    public class DynamicDataSourceServiceImpl implements DynamicDataSourceService { 
    
        @Resource
        private UserDao userDao;
        @Resource
        private SystemLogDao systemLogDao;
    
        @Override
        @DataSource(value = MultiDataSource.MASTER_DATA_SOURCE)
        public void addUserInfo(User user) { 
            userDao.insert(user);
        }
    
        @Override
        @DataSource(value = MultiDataSource.MASTER_DATA_SOURCE)
        public User getUserInfo(String username) { 
            return userDao.findByUsername(username);
        }
    
        @Override
        @DataSource(value = MultiDataSource.LOG_DATA_SOURCE)
        public void addSystemLog(SystemLog systemLog) { 
            systemLogDao.insert(systemLog);
        }
    
        @Override
        @DataSource(value = MultiDataSource.LOG_DATA_SOURCE)
        public List<SystemLog> getSystemLogInfo(Date beginTime, Date endTime) { 
            return systemLogDao.findByCreateTime(beginTime, endTime);
        }
    }

#### 案例源码 ####

案例源码地址： [https://github.com/lazycece/springboot-actual-combat/tree/master/springboot-ac-mysql/springboot-ac-mysql-multi][https_github.com_lazycece_springboot-actual-combat_tree_master_springboot-ac-mysql_springboot-ac-mysql-multi]

[springboot_mysql_mybatis]: https://lazycece.github.io/2019/05/04/springboot%E4%B8%ADmysql%E4%B8%8Emybatis%E7%9A%84%E5%BC%95%E5%85%A5/
[https_github.com_lazycece_springboot-actual-combat_tree_master_springboot-ac-mysql_springboot-ac-mysql-multi]: https://github.com/lazycece/springboot-actual-combat/tree/master/springboot-ac-mysql/springboot-ac-mysql-multi