springboot中mybatis多数据源动态切换实现

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。

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);

									    }

									}