Ajax解决多余刷新的两种方法(总结)

控制器Servlet则提供了简单的改变：

对于Ajax系统而言，服务器响应无须是整个页面内容，可以仅是

必需的数据，控制器不能将数据请求转发到jsp页面。

此时控制器有两个选择：

1、直接生成简单的响应数据。

在这种模式下，Servlet直接通过response获取页面输出流，通过

输出流生成字符响应。

package pers.zkr.chat.web;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import pers.zkr.chat.service.ChatService;@WebServlet(urlPatterns={"/chat.do"})public class ChatServlet extends HttpServlet { @Override public void service(HttpServletRequest request, HttpServletResponse response)  throws ServletException, IOException { // TODO Auto-generated method stub  request.setCharacterEncoding("utf-8");   String msg=request.getParameter("chatMsg"); System.out.println(msg);  if(msg!=null&&!msg.equals("")){  String user=(String)request.getSession().getAttribute("user");  System.out.println(user+"user");  ChatService.instance().addMsg(user, msg);   }  //设置响应内容的类型 <strong>response.setContentType("text/html;charset=utf-8"); // 获取页面输出流 PrintWriter out = response.getWriter(); //直接生成响应 out.println(ChatService.instance().getMsg());</strong>  request.setAttribute("msg",ChatService.instance().getMsg());  forward("/chat.jsp", request , response); } private void forward(String url, HttpServletRequest request,  HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub  request.getRequestDispatcher(url)   .forward(request , response);   } }    

2、转向一个简单的jsp使用JSP页面生成简单的响应。

控制器将请求转发到另外的JSP页面，而JSP页面仅仅负责输出聊天信息

在这里需要一个jsp页面来接收控制器发来的数据，也是服务器的响应文本，而在

原来的页面，只需：

1）创建XMLHttpRequest对象

2) 发送请求

3）接收服务器的响应

package org.crazyit.chat.web;import javax.servlet.*;import javax.servlet.http.*;import javax.servlet.annotation.*;import java.io.*;import org.crazyit.chat.service.*;/** * Description: * <br/>网站: <a href=//www.Vevb.com>错新站长站</a> * <br/>Copyright (C), 2001-2014, Yeeku.H.Lee * <br/>This program is protected by copyright laws. * <br/>Program Name: * <br/>Date: * @version 1.0 */@WebServlet(urlPatterns={"/chat.do"})public class ChatServlet extends HttpServlet{ public void service(HttpServletRequest request, HttpServletResponse response)throws IOException,ServletException { // 设置使用GBK字符集来解析请求参数 request.setCharacterEncoding("utf-8"); String msg = request.getParameter("chatMsg"); if ( msg != null && !msg.equals("")) {  // 取得当前用户  String user = (String)request.getSession(true)  .getAttribute("user");  // 调用ChatService的addMsg来添加聊天消息  ChatService.instance().addMsg(user , msg); } // 将全部聊天信息设置成request属性 <strong>request.setAttribute("chatList" ,  ChatService.instance().getMsg());</strong> // 转发到chatreply.jsp页面 forward("/chatreply.jsp" , request , response); } // 执行转发请求的方法 private void forward(String url , HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException { // 执行转发 request.getRequestDispatcher(url)  .forward(request,response); }}