spring实现动态切换、添加数据源及源码分析

/**
 * 多数据源配置
 * 
 * @author Taven
 *
 */
@Configuration
@MapperScan("com.gitee.taven.mapper")
public class DataSourceConfigurer {

 /**
  * DataSource 自动配置并注册
  *
  * @return data source
  */
 @Bean("db0")
 @Primary
 @ConfigurationProperties(prefix = "datasource.db0")
 public DataSource dataSource0() {
  return DruidDataSourceBuilder.create().build();
 }

 /**
  * DataSource 自动配置并注册
  *
  * @return data source
  */
 @Bean("db1")
 @ConfigurationProperties(prefix = "datasource.db1")
 public DataSource dataSource1() {
  return DruidDataSourceBuilder.create().build();
 }

 /**
  * 注册动态数据源
  * 
  * @return
  */
 @Bean("dynamicDataSource")
 public DataSource dynamicDataSource() {
  DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();
  Map dataSourceMap = new HashMap<>();
  dataSourceMap.put("dynamic_db0", dataSource0());
  dataSourceMap.put("dynamic_db1", dataSource1());
  dynamicRoutingDataSource.setDefaultTargetDataSource(dataSource0());// 设置默认数据源
  dynamicRoutingDataSource.setTargetDataSources(dataSourceMap);
  return dynamicRoutingDataSource;
 }

 /**
  * Sql session factory bean.
  * Here to config datasource for SqlSessionFactory
  * 

  * You need to add @{@code @ConfigurationProperties(prefix = "mybatis")}, if you are using *.xml file,
  * the {@code 'mybatis.type-aliases-package'} and {@code 'mybatis.mapper-locations'} should be set in
  * {@code 'application.properties'} file, or there will appear invalid bond statement exception
  *
  * @return the sql session factory bean
  */
 @Bean
 @ConfigurationProperties(prefix = "mybatis")
 public SqlSessionFactoryBean sqlSessionFactoryBean() {
  SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
  // 必须将动态数据源添加到 sqlSessionFactoryBean
  sqlSessionFactoryBean.setDataSource(dynamicDataSource());
  return sqlSessionFactoryBean;
 }

 /**
  * 事务管理器
  *
  * @return the platform transaction manager
  */
 @Bean
 public PlatformTransactionManager transactionManager() {
  return new DataSourceTransactionManager(dynamicDataSource());
 }
}

package com.gitee.taven.config;

public class DynamicDataSourceContextHolder {

 private static final ThreadLocal contextHolder = new ThreadLocal() {
  @Override
  protected String initialValue() {
   return "dynamic_db0";
  }
 };

 /**
  * To switch DataSource
  *
  * @param key the key
  */
 public static void setDataSourceKey(String key) {
  contextHolder.set(key);
 }

 /**
  * Get current DataSource
  *
  * @return data source key
  */
 public static String getDataSourceKey() {
  return contextHolder.get();
 }

 /**
  * To set DataSource as default
  */
 public static void clearDataSourceKey() {
  contextHolder.remove();
 }
}

/**
 * 动态数据源
 * 
 * @author Taven
 *
 */
public class DynamicRoutingDataSource extends AbstractRoutingDataSource {

 private final Logger logger = LoggerFactory.getLogger(getClass());

 private static Map targetDataSources = new HashMap<>();
 
 /**
  * 设置当前数据源
  *
  * @return
  */
 @Override
 protected Object determineCurrentLookupKey() {
  logger.info("Current DataSource is [{}]", DynamicDataSourceContextHolder.getDataSourceKey());
  return DynamicDataSourceContextHolder.getDataSourceKey();
 }
 
 @Override
 public void setTargetDataSources(Map targetDataSources) {
  super.setTargetDataSources(targetDataSources);
  DynamicRoutingDataSource.targetDataSources = targetDataSources;
 }
 
 /**
  * 是否存在当前key的 DataSource
  * 
  * @param key
  * @return 存在返回 true, 不存在返回 false
  */
 public static boolean isExistDataSource(String key) {
  return targetDataSources.containsKey(key);
 }
 
 /**
  * 动态增加数据源
  * 
  * @param map 数据源属性
  * @return
  */
 public synchronized boolean addDataSource(Map map) {
  try {
   Connection connection = null;
   // 排除连接不上的错误
   try { 
    Class.forName(map.get(DruidDataSourceFactory.PROP_DRIVERCLASSNAME));
    connection = DriverManager.getConnection(
      map.get(DruidDataSourceFactory.PROP_URL), 
      map.get(DruidDataSourceFactory.PROP_USERNAME),
      map.get(DruidDataSourceFactory.PROP_PASSWORD));
    System.out.println(connection.isClosed());
   } catch (Exception e) {
    return false;
   } finally {
    if (connection != null && !connection.isClosed()) 
     connection.close();
   }
   String database = map.get("database");//获取要添加的数据库名
   if (StringUtils.isBlank(database)) return false;
   if (DynamicRoutingDataSource.isExistDataSource(database)) return true; 
   DruidDataSource druidDataSource = (DruidDataSource) DruidDataSourceFactory.createDataSource(map);
   druidDataSource.init();
   Map targetMap = DynamicRoutingDataSource.targetDataSources;
   targetMap.put(database, druidDataSource);
   // 当前 targetDataSources 与 父类 targetDataSources 为同一对象 所以不需要set
//   this.setTargetDataSources(targetMap);
   this.afterPropertiesSet();
   logger.info("dataSource {} has been added", database);
  } catch (Exception e) {
   logger.error(e.getMessage());
   return false;
  }
  return true;
 } 
}