servlet无法返回结果

Question

servlet无法返回结果，sql是可以查出结果的但客户端无法获得。public void actionPerformed(ActionEvent e)  {
    try{
       String data = URLEncoder.encode("sql", "UTF-8") + "=" + URLEncoder.encode("select gsjc,gsbh from ld_gs", "UTF-8");
      URL url = new URL("http://192.168.0.117:8080/servlet1");
      URLConnection urlcon = url.openConnection();
      urlcon.setDoOutput(true);
      urlcon.connect();
      System.out.println("建立连接");
      OutputStreamWriter wr = new OutputStreamWriter(urlcon.getOutputStream());
       wr.write(data);
       wr.flush();      ObjectInputStream ois=new ObjectInputStream(urlcon.getInputStream());//和servlet建立连接
//CachedRowSetImpl crs = (CachedRowSetImpl)ois.readObject();
     ResultSet rst = (ResultSet)ois.readObject();
      while(rst.next())
      {
        String sqlname = rst.getString("gsjc");
        System.out.println(sqlname);
      }    }    catch(Exception e1){
    }    }
servlet代码如下:  Class.forName("oracle.jdbc.driver.OracleDriver");
   conn = DriverManager.getConnection("dbc:oracle:thin:@192.168.0.100:1521:dc","hydbuser","hydbuser");
   Statement sta = conn.createStatement();
   String sql = request.getParameter("sql");
   System.out.println("sql:"+sql);
   ResultSet rst = sta.executeQuery(sql);
    //CachedRowSetImpl crs = new CachedRowSetImpl();
//crs.populate(rst);
// while(rst.next())
//  {
//  String sqlname = rst.getString("gsjc");
//  System.out.println(sqlname);
// }
// rst.close();
// sta.close();
// conn.close();   response.setContentType("application/octet-stream");
   ObjectOutputStream oos = new ObjectOutputStream(response.getOutputStream());
   oos.writeObject(rst);//传递结果集
   oos.close();
   rst.close();
   sta.close();
   conn.close();
}