本文小编为大家详细介绍“SpringBoot基于AbstractRoutingDataSource如何实现多数据源动态切换”，内容详细，步骤清晰，细节处理妥当，希望这篇“SpringBoot基于AbstractRoutingDataSource如何实现多数据源动态切换”文章能帮助大家解决疑惑，下面跟着小编的思路慢慢深入，一起来学习新知识吧。
一、场景
在生产业务中，有一些任务执行了耗时较长的查询操作，在实时性要求不高的时候，我们希望将这些查询sql分离出来，去从库查询，以减少应用对主数据库的压力。
一种方案是在配置文件中配置多个数据源，然后通过配置类来获取数据源以及mapper相关的扫描配置，不同的数据源配置不佟的mapper扫描位置，然后需要哪一个数据源就注入哪一个mapper接口即可，这种方法比较简单。特征是通过mapper扫描位置区分数据源。
第二种方案是配置一个默认使用的数据源，然后定义多个其他的数据源，使用aop形成注解式选择数据源。此种方案实现的核心是对AbstractRoutingDataSource 类的继承。这是本文的重点。
二、原理
AbstractRoutingDataSource的多数据源动态切换的核心逻辑是：在程序运行时，把数据源数据源通过 AbstractRoutingDataSource 动态织入到程序中，灵活的进行数据源切换。
基于AbstractRoutingDataSource的多数据源动态切换，可以实现读写分离。逻辑如下：
protected DataSource determineTargetDataSource() { Assert.notNull(this.resolvedDataSources, "DataSource router not initialized"); Object lookupKey = determineCurrentLookupKey(); DataSource dataSource = this.resolvedDataSources.get(lookupKey); if (dataSource == null && (this.lenientFallback || lookupKey == null)) { dataSource = this.resolvedDefaultDataSource; } if (dataSource == null) { throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]"); } return dataSource; } @Nullable protected abstract Object determineCurrentLookupKey();通过实现抽象方法determineCurrentLookupKey指定需要切换的数据源
三、代码示例
示例中主要依赖
com.alibaba.druid;tk.mybatis
定义一个类用于关联数据源。通过 TheadLocal 来保存每个线程选择哪个数据源的标志(key)
@Slf4jpublic class DynamicDataSourceContextHolder { private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>(); public static List<String> dataSourceIds = new ArrayList<String>(); public static void setDataSourceType(String dataSourceType) { log.info("设置当前数据源为{}",dataSourceType); contextHolder.set(dataSourceType); } public static String getDataSourceType() { return contextHolder.get() ; } public static void clearDataSourceType() { contextHolder.remove(); } public static boolean containsDataSource(String dataSourceId){ log.info("list = {},dataId={}", JSON.toJSON(dataSourceIds),dataSourceId); return dataSourceIds.contains(dataSourceId); }}继承
AbstractRoutingDataSource
public class DynamicDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return DynamicDataSourceContextHolder.getDataSourceType(); }}配置主数据库master 与从数据库slave（略）。数据源配置可以从简
@Configuration@tk.mybatis.spring.annotation.MapperScan(value = {"com.server.dal.dao"})@ConditionalOnProperty(name = "java.druid.datasource.master.url")public class JavaDruidDataSourceConfiguration { private static final Logger logger = LoggerFactory.getLogger(JavaDruidDataSourceConfiguration.class); @Resource private JavaDruidDataSourceProperties druidDataSourceProperties; @Primary @Bean(name = "masterDataSource", initMethod = "init", destroyMethod = "close") @ConditionalOnMissingBean(name = "masterDataSource") public DruidDataSource javaReadDruidDataSource() { DruidDataSource result = new DruidDataSource(); try {// result.setName(druidDataSourceProperties.getName()); result.setUrl(druidDataSourceProperties.getUrl()); result.setUsername(druidDataSourceProperties.getUsername()); result.setPassword(druidDataSourceProperties.getPassword()); result.setConnectionProperties( "config.decrypt=false;config.decrypt.key=" + druidDataSourceProperties.getPwdPublicKey()); result.setFilters("config"); result.setMaxActive(druidDataSourceProperties.getMaxActive()); result.setInitialSize(druidDataSourceProperties.getInitialSize()); result.setMaxWait(druidDataSourceProperties.getMaxWait()); result.setMinIdle(druidDataSourceProperties.getMinIdle()); result.setTimeBetweenEvictionRunsMillis(druidDataSourceProperties.getTimeBetweenEvictionRunsMillis()); result.setMinEvictableIdleTimeMillis(druidDataSourceProperties.getMinEvictableIdleTimeMillis()); result.setValidationQuery(druidDataSourceProperties.getValidationQuery()); result.setTestWhileIdle(druidDataSourceProperties.isTestWhileIdle()); result.setTestOnBorrow(druidDataSourceProperties.isTestOnBorrow()); result.setTestOnReturn(druidDataSourceProperties.isTestOnReturn()); result.setPoolPreparedStatements(druidDataSourceProperties.isPoolPreparedStatements()); result.setMaxOpenPreparedStatements(druidDataSourceProperties.getMaxOpenPreparedStatements()); if (druidDataSourceProperties.isEnableMonitor()) { StatFilter filter = new StatFilter(); filter.setLogSlowSql(druidDataSourceProperties.isLogSlowSql()); filter.setMergeSql(druidDataSourceProperties.isMergeSql()); filter.setSlowSqlMillis(druidDataSourceProperties.getSlowSqlMillis()); List<Filter> list = new ArrayList<>(); list.add(filter); result.setProxyFilters(list); } } catch (Exception e) { logger.error("数据源加载失败:", e); } finally { result.close(); } return result; }}注意主从数据库的bean name
配置DynamicDataSource
targetDataSources 存放数据源的k-v对
defaultTargetDataSource 存放默认数据源
配置事务管理器和SqlSessionFactoryBean
@Configurationpublic class DynamicDataSourceConfig { private static final String MAPPER_LOCATION = "classpath*:sqlmap/dao/*Mapper.xml"; @Bean(name = "dynamicDataSource") public DynamicDataSource dynamicDataSource(@Qualifier("masterDataSource") DruidDataSource masterDataSource, @Qualifier("slaveDataSource") DruidDataSource slaveDataSource) { Map<Object, Object> targetDataSource = new HashMap<>(); DynamicDataSourceContextHolder.dataSourceIds.add("masterDataSource"); targetDataSource.put("masterDataSource", masterDataSource); DynamicDataSourceContextHolder.dataSourceIds.add("slaveDataSource"); targetDataSource.put("slaveDataSource", slaveDataSource); DynamicDataSource dataSource = new DynamicDataSource(); dataSource.setTargetDataSources(targetDataSource); dataSource.setDefaultTargetDataSource(masterDataSource); return dataSource; } @Primary @Bean(name = "javaTransactionManager") @ConditionalOnMissingBean(name = "javaTransactionManager") public DataSourceTransactionManager transactionManager(@Qualifier("dynamicDataSource") DynamicDataSource druidDataSource) { return new DataSourceTransactionManager(druidDataSource); } @Bean(name = "sqlSessionFactoryBean") public SqlSessionFactoryBean myGetSqlSessionFactory(@Qualifier("dynamicDataSource") DynamicDataSource dataSource) { SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(); try { sqlSessionFactoryBean.setMapperLocations(resolver.getResources(MAPPER_LOCATION)); } catch (IOException e) { e.printStackTrace(); } sqlSessionFactoryBean.setDataSource(dataSource); return sqlSessionFactoryBean; }}定义一个注解用于指定数据源
@Target({ ElementType.METHOD, ElementType.TYPE })@Retention(RetentionPolicy.RUNTIME)@Documentedpublic @interface TargetDataSource { String value();}切面的业务逻辑。注意指定order，以确保在开启事务之前执行 。
@Aspect@Slf4j@Order(-1)@Componentpublic class DataSourceAop { @Before("@annotation(targetDataSource)") public void changeDataSource(JoinPoint point, TargetDataSource targetDataSource) { String dsId = targetDataSource.value(); if (!DynamicDataSourceContextHolder.containsDataSource(dsId)) { log.error("数据源[{}]不存在，使用默认数据源 > {}" + targetDataSource.value() + point.getSignature()); } else { log.info("UseDataSource : {} > {}" + targetDataSource.value() + point.getSignature()); DynamicDataSourceContextHolder.setDataSourceType(targetDataSource.value()); } } @After("@annotation(targetDataSource)") public void restoreDataSource(JoinPoint point, TargetDataSource targetDataSource) { log.info("RevertDataSource : {} > {}"+targetDataSource.value()+point.getSignature()); DynamicDataSourceContextHolder.clearDataSourceType(); }}以上略去了pom.xml和application.yml
使用示例
@Resource private ShopBillDOMapper shopBillDOMapper; //使用默认数据源 public ShopBillBO queryTestData(Integer id){ return shopBillDOMapper.getByShopBillId(id); } //切换到指定的数据源 @TargetDataSource("slaveDataSource") public ShopBill queryTestData2(Integer id){ return shopBillDOMapper.getByShopBillId(id); }如果返回不同的结果就成功了！
读到这里，这篇“SpringBoot基于AbstractRoutingDataSource如何实现多数据源动态切换”文章已经介绍完毕，想要掌握这篇文章的知识点还需要大家自己动手实践使用过才能领会，如果想了解更多相关内容的文章，欢迎关注编程网行业资讯频道。
