【Java Web开发学习】DataSource获取的Connection要不要关闭

先给答案：要关闭

官方文档：https://docs.oracle.com/javase/tutorial/jdbc/basics/sqldatasources.html#pooled_connection

我们以 HikariDataSource 为例子

@Autowired
DataSource dataSource;

Connection con = dataSource.getConnection();
con.close();

dataSource 会注入 HikariDataSource 对象，该对象实现了DataSource接口

public class HikariDataSource extends HikariConfig implements DataSource, Closeable

dataSource.getConnection() 获取的连接是一个代理对象 com.zaxxer.hikari.pool.ProxyConnection，看下close方法，并不是真的关闭了TCP连接，而是回收了。

   @Override
   public final void close() throws SQLException
   {
      // Closing statements can cause connection eviction, so this must run before the conditional below
      closeStatements();

      if (delegate != ClosedConnection.CLOSED_CONNECTION) {
         leakTask.cancel();

         try {
            if (isCommitStateDirty && !isAutoCommit) {
               delegate.rollback();
               lastAccess = currentTime();
               LOGGER.debug("{} - Executed rollback on connection {} due to dirty commit state on close().", poolEntry.getPoolName(), delegate);
            }

            if (dirtyBits != 0) {
               poolEntry.resetConnectionState(this, dirtyBits);
               lastAccess = currentTime();
            }

            delegate.clearWarnings();
         }
         catch (SQLException e) {
            // when connections are aborted, exceptions are often thrown that should not reach the application
            if (!poolEntry.isMarkedEvicted()) {
               throw checkException(e);
            }
         }
         finally {
            delegate = ClosedConnection.CLOSED_CONNECTION;
            poolEntry.recycle(lastAccess);
         }
      }
   }