Spring boot配置多数据源&读AbstractRoutingDataSource源码

引用:https://blog.csdn.net/qq_45515182/article/details/126330084 (直接看Spring AOP + 自定义注解)

下面我们阅读下AbstractRoutingDataSource的源码,逻辑还是挺简单的

AbstractRoutingDataSource

step1:

@Override
public Connection getConnection() throws SQLException {
   return determineTargetDataSource().getConnection();
}

step2:

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;
}

step3:

determineCurrentLookupKey()子类实现

public static ThreadLocal<String> flag = new ThreadLocal<>();
@Override    
protected Object determineCurrentLookupKey() { 
     return flag.get();   
}

resolvedDataSources通过afterPropertiesSet进行赋值

@Override
    public void afterPropertiesSet() {
        Map<Object,Object> targetDataSource = new ConcurrentHashMap<>();
        targetDataSource.put(DataSourceType.MYSQL_DATASOURCE1.name(),mysqlDataSource1);
        targetDataSource.put(DataSourceType.MYSQL_DATASOURCE2.name(),mysqlDataSource2);
        super.setTargetDataSources(targetDataSource);
        super.setDefaultTargetDataSource(mysqlDataSource1);
        super.afterPropertiesSet();
    }

step4:

resolveSpecifiedLookupKey和resolveSpecifiedDataSource可以忽略

应对一些定制的奇奇怪怪的需求的

@Override
public void afterPropertiesSet() {
   if (this.targetDataSources == null) {
      throw new IllegalArgumentException("Property 'targetDataSources' is required");
   }
   this.resolvedDataSources = CollectionUtils.newHashMap(this.targetDataSources.size());
   this.targetDataSources.forEach((key, value) -> {
      Object lookupKey = resolveSpecifiedLookupKey(key);
      DataSource dataSource = resolveSpecifiedDataSource(value);
      this.resolvedDataSources.put(lookupKey, dataSource);
   });
   if (this.defaultTargetDataSource != null) {
      this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
   }
}