Spring动态注册多数据源的实现方法

TenantConfigEntity（租户信息）
@EqualsAndHashCode(callSuper = false)
@Data
@FieldDefaults(level = AccessLevel.PRIVATE)
public class TenantConfigEntity {
 /**
  * 租户id
  **/
 Integer tenantId;
 /**
  * 租户名称
  **/
 String tenantName;
 /**
  * 租户名称key
  **/
 String tenantKey;
 /**
  * 数据库url
  **/
 String dbUrl;
 /**
  * 数据库用户名
  **/
 String dbUser;
 /**
  * 数据库密码
  **/
 String dbPassword;
 /**
  * 数据库public_key
  **/
 String dbPublicKey;
}
DataSourceUtil（辅助工具类，非必要）
public class DataSourceUtil {
 private static final String DATA_SOURCE_BEAN_KEY_SUFFIX = "_data_source";
 private static final String JDBC_URL_ARGS = "?useUnicode=true&characterEncoding=UTF-8&useOldAliasMetadataBehavior=true&zeroDateTimeBehavior=convertToNull";
 private static final String CONNECTION_PROPERTIES = "config.decrypt=true;config.decrypt.key=";
 /**
  * 拼接数据源的spring bean key
  */
 public static String getDataSourceBeanKey(String tenantKey) {
  if (!StringUtils.hasText(tenantKey)) {
   return null;
  }
  return tenantKey + DATA_SOURCE_BEAN_KEY_SUFFIX;
 }
 /**
  * 拼接完整的JDBC URL
  */
 public static String getJDBCUrl(String baseUrl) {
  if (!StringUtils.hasText(baseUrl)) {
   return null;
  }
  return baseUrl + JDBC_URL_ARGS;
 }
 /**
  * 拼接完整的Druid连接属性
  */
 public static String getConnectionProperties(String publicKey) {
  if (!StringUtils.hasText(publicKey)) {
   return null;
  }
  return CONNECTION_PROPERTIES + publicKey;
 }
}

public class DataSourceContextHolder {
 private static final ThreadLocal<String> dataSourceKey = new InheritableThreadLocal<>();
 public static void setDataSourceKey(String tenantKey) {
  dataSourceKey.set(tenantKey);
 }
 public static String getDataSourceKey() {
  return dataSourceKey.get();
 }
 public static void clearDataSourceKey() {
  dataSourceKey.remove();
 }
}

public class DynamicDataSource extends AbstractRoutingDataSource {
 @Autowired
 private ApplicationContext applicationContext;
 @Lazy
 @Autowired
 private DynamicDataSourceSummoner summoner;
 @Lazy
 @Autowired
 private TenantConfigDAO tenantConfigDAO;
 @Override
 protected String determineCurrentLookupKey() {
  String tenantKey = DataSourceContextHolder.getDataSourceKey();
  return DataSourceUtil.getDataSourceBeanKey(tenantKey);
 }
 @Override
 protected DataSource determineTargetDataSource() {
  String tenantKey = DataSourceContextHolder.getDataSourceKey();
  String beanKey = DataSourceUtil.getDataSourceBeanKey(tenantKey);
  if (!StringUtils.hasText(tenantKey) || applicationContext.containsBean(beanKey)) {
   return super.determineTargetDataSource();
  }
  if (tenantConfigDAO.exist(tenantKey)) {
   summoner.registerDynamicDataSources();
  }
  return super.determineTargetDataSource();
 }
}

@Slf4j
@Component
public class DynamicDataSourceSummoner implements ApplicationListener<ContextRefreshedEvent> {
 // 跟spring-data-source.xml的默认数据源id保持一致
 private static final String DEFAULT_DATA_SOURCE_BEAN_KEY = "defaultDataSource";
 @Autowired
 private ConfigurableApplicationContext applicationContext;
 @Autowired
 private DynamicDataSource dynamicDataSource;
 @Autowired
 private TenantConfigDAO tenantConfigDAO;
 private static boolean loaded = false;
 /**
  * Spring加载完成后执行
  */
 @Override
 public void onApplicationEvent(ContextRefreshedEvent event) {
  // 防止重复执行
  if (!loaded) {
   loaded = true;
   try {
    registerDynamicDataSources();
   } catch (Exception e) {
    log.error("数据源初始化失败, Exception:", e);
   }
  }
 }
 /**
  * 从数据库读取租户的DB配置,并动态注入Spring容器
  */
 public void registerDynamicDataSources() {
  // 获取所有租户的DB配置
  List<TenantConfigEntity> tenantConfigEntities = tenantConfigDAO.listAll();
  if (CollectionUtils.isEmpty(tenantConfigEntities)) {
   throw new IllegalStateException("应用程序初始化失败,请先配置数据源");
  }
  // 把数据源bean注册到容器中
  addDataSourceBeans(tenantConfigEntities);
 }
 /**
  * 根据DataSource创建bean并注册到容器中
  */
 private void addDataSourceBeans(List<TenantConfigEntity> tenantConfigEntities) {
  Map<Object, Object> targetDataSources = Maps.newLinkedHashMap();
  DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) applicationContext.getAutowireCapableBeanFactory();
  for (TenantConfigEntity entity : tenantConfigEntities) {
   String beanKey = DataSourceUtil.getDataSourceBeanKey(entity.getTenantKey());
   // 如果该数据源已经在spring里面注册过,则不重新注册
   if (applicationContext.containsBean(beanKey)) {
    DruidDataSource existsDataSource = applicationContext.getBean(beanKey, DruidDataSource.class);
    if (isSameDataSource(existsDataSource, entity)) {
     continue;
    }
   }
   // 组装bean
   AbstractBeanDefinition beanDefinition = getBeanDefinition(entity, beanKey);
   // 注册bean
   beanFactory.registerBeanDefinition(beanKey, beanDefinition);
   // 放入map中，注意一定是刚才创建bean对象
   targetDataSources.put(beanKey, applicationContext.getBean(beanKey));
  }
  // 将创建的map对象set到 targetDataSources；
  dynamicDataSource.setTargetDataSources(targetDataSources);
  // 必须执行此操作，才会重新初始化AbstractRoutingDataSource 中的 resolvedDataSources，也只有这样，动态切换才会起效
  dynamicDataSource.afterPropertiesSet();
 }
 /**
  * 组装数据源spring bean
  */
 private AbstractBeanDefinition getBeanDefinition(TenantConfigEntity entity, String beanKey) {
  BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(DruidDataSource.class);
  builder.getBeanDefinition().setAttribute("id", beanKey);
  // 其他配置继承defaultDataSource
  builder.setParentName(DEFAULT_DATA_SOURCE_BEAN_KEY);
  builder.setInitMethodName("init");
  builder.setDestroyMethodName("close");
  builder.addPropertyValue("name", beanKey);
  builder.addPropertyValue("url", DataSourceUtil.getJDBCUrl(entity.getDbUrl()));
  builder.addPropertyValue("username", entity.getDbUser());
  builder.addPropertyValue("password", entity.getDbPassword());
  builder.addPropertyValue("connectionProperties", DataSourceUtil.getConnectionProperties(entity.getDbPublicKey()));
  return builder.getBeanDefinition();
 }
 /**
  * 判断Spring容器里面的DataSource与数据库的DataSource信息是否一致
  * 备注:这里没有判断public_key,因为另外三个信息基本可以确定唯一了
  */
 private boolean isSameDataSource(DruidDataSource existsDataSource, TenantConfigEntity entity) {
  boolean sameUrl = Objects.equals(existsDataSource.getUrl(), DataSourceUtil.getJDBCUrl(entity.getDbUrl()));
  if (!sameUrl) {
   return false;
  }
  boolean sameUser = Objects.equals(existsDataSource.getUsername(), entity.getDbUser());
  if (!sameUser) {
   return false;
  }
  try {
   String decryptPassword = ConfigTools.decrypt(entity.getDbPublicKey(), entity.getDbPassword());
   return Objects.equals(existsDataSource.getPassword(), decryptPassword);
  } catch (Exception e) {
   log.error("数据源密码校验失败,Exception:{}", e);
   return false;
  }
 }
}

<!-- 引入jdbc配置文件 -->
 <context:property-placeholder location="classpath:data.properties" ignore-unresolvable="true"/>
 <!-- 公共(默认)数据源 -->
 <bean id="defaultDataSource" class="com.alibaba.druid.pool.DruidDataSource"
   init-method="init" destroy-method="close">
  <!-- 基本属性 url、user、password -->
  <property name="url" value="${ds.jdbcUrl}" />
  <property name="username" value="${ds.user}" />
  <property name="password" value="${ds.password}" />
  <!-- 配置初始化大小、最小、最大 -->
  <property name="initialSize" value="5" />
  <property name="minIdle" value="2" />
  <property name="maxActive" value="10" />
  <!-- 配置获取连接等待超时的时间，单位是毫秒 -->
  <property name="maxWait" value="1000" />
  <!-- 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒 -->
  <property name="timeBetweenEvictionRunsMillis" value="5000" />
  <!-- 配置一个连接在池中最小生存的时间，单位是毫秒 -->
  <property name="minEvictableIdleTimeMillis" value="240000" />
  <property name="validationQuery" value="SELECT 1" />
  <!--单位：秒，检测连接是否有效的超时时间-->
  <property name="validationQueryTimeout" value="60" />
  <!--建议配置为true，不影响性能，并且保证安全性。申请连接的时候检测，如果空闲时间大于timeBetweenEvictionRunsMillis，执行validationQuery检测连接是否有效-->
  <property name="testWhileIdle" value="true" />
  <!--申请连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能。-->
  <property name="testOnBorrow" value="true" />
  <!--归还连接时执行validationQuery检测连接是否有效，做了这个配置会降低性能。-->
  <property name="testOnReturn" value="false" />
  <!--Config Filter-->
  <property name="filters" value="config" />
  <property name="connectionProperties" value="config.decrypt=true;config.decrypt.key=${ds.publickey}" />
 </bean>
 <!-- 事务管理器 -->
 <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
  <property name="dataSource" ref="multipleDataSource"/>
 </bean>
 <!--多数据源-->
 <bean id="multipleDataSource" class="a.b.c.DynamicDataSource">
  <property name="defaultTargetDataSource" ref="defaultDataSource"/>
  <property name="targetDataSources">
   <map>
    <entry key="defaultDataSource" value-ref="defaultDataSource"/>
   </map>
  </property>
 </bean>
 <!-- 注解事务管理器 -->
 <!--这里的order值必须大于DynamicDataSourceAspectAdvice的order值-->
 <tx:annotation-driven transaction-manager="txManager" order="2"/>
 <!-- 创建SqlSessionFactory，同时指定数据源 -->
 <bean id="mainSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
  <property name="dataSource" ref="multipleDataSource"/>
 </bean>
 <!-- DAO接口所在包名，Spring会自动查找其下的DAO -->
 <bean id="mainSqlMapper" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
  <property name="sqlSessionFactoryBeanName" value="mainSqlSessionFactory"/>
  <property name="basePackage" value="a.b.c.*.dao"/>
 </bean>
 <bean id="defaultSqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
  <property name="dataSource" ref="defaultDataSource"/>
 </bean>
 <bean id="defaultSqlMapper" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
  <property name="sqlSessionFactoryBeanName" value="defaultSqlSessionFactory"/>
  <property name="basePackage" value="a.b.c.base.dal.dao"/>
 </bean>
 <!-- 其他配置省略 -->

@Slf4j
@Aspect
@Component
@Order(1) // 请注意：这里order一定要小于tx:annotation-driven的order，即先执行DynamicDataSourceAspectAdvice切面，再执行事务切面，才能获取到最终的数据源
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class DynamicDataSourceAspectAdvice {
 @Around("execution(* a.b.c.*.controller.*.*(..))")
 public Object doAround(ProceedingJoinPoint jp) throws Throwable {
  ServletRequestAttributes sra = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
  HttpServletRequest request = sra.getRequest();
  HttpServletResponse response = sra.getResponse();
  String tenantKey = request.getHeader("tenant");
  // 前端必须传入tenant header, 否则返回400
  if (!StringUtils.hasText(tenantKey)) {
   WebUtils.toHttp(response).sendError(HttpServletResponse.SC_BAD_REQUEST);
   return null;
  }
  log.info("当前租户key:{}", tenantKey);
  DataSourceContextHolder.setDataSourceKey(tenantKey);
  Object result = jp.proceed();
  DataSourceContextHolder.clearDataSourceKey();
  return result;
 }
}