数据库关闭连接

     try{
     if (conn != null && stm != null && res != null) {
      conn.close();
      stm.close();
      res.close();
    }
    } catch(Exception e){
      e.printStackTrace();
      System.out.println( "关闭数据库连接出错！");
    }

上述代码会导致报错，因为stm关闭时res也同时关闭，执行res.close()时res已经关闭，所以导致报错。

以下代码为正确。

                 try {
                         if (res != null)
                                res.close();
                } catch (Exception e) {
                        e.printStackTrace();
                }
                 try {
                         if (stm != null)
                                stm.close();
                } catch (Exception e) {
                        e.printStackTrace();
                }
                 try {
                         if (conn != null) {
                          conn.close();
                        }
                } catch (Exception e) {
                        e.printStackTrace();
                }