Ajax技术--服务器返回数据格式（HTML,XML,JSON）

来源：互联网发布：大数据技术体系编辑：程序博客网时间：2024/04/30 21:06

默认情况下返回HTML格式，所以不必设置，直接输出即可，案例：实时显示聊天内容

2、返回XML格式：

XML中常用attr()返回节点属性，应用find()方法获取XML文档文本节点

index.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--><script type="text/javascript" src ="js/jquery-3.1.1.min.js"></script><script type="text/javascript">   function getContent(){      $.get("ChatServlet?action=get&nocache"+new Date().getTime(),function(data){      var msg = "";      $(data).find("massage").each(function(){      msg += "<br>" + $(this).text();      });              $("#div1").html(msg);      },"XML");   }      $(document).ready(function(){     getContent();     setInterval("getContent()",1000);  //必须加引号   });      $(document).ready(function(){     $("#btn").click(function(){       if($("#user").val() != ""){         if($("#speak").val() != ""){            $.post("ChatServlet?action=send",{  //$.post(url,data,success())方法           user:$("#user").val(),           speak:$("#speak").val()});                                 $("#speak").val("") ; //清空说话文本内容           $("#speak").focus();                    }else {           alert("说话内容不能为空");         }       }else {        alert("用户名不能为空");       }     });   });      </script>  </head>  　　　　  <body>    <div id = "div1" style = "height: 135px;background:red ;overflow:hidden"> 欢迎光临阿文聊天室</div>      <form action="" method = "post" name = "form1">      <input name = "user" type = "text" size = "20" id = "user">说：      <input name = "speak" type = "text" size = "50" id = "speak">        <input name = "btn" type = "button" id = "btn" value ="发送">         </form>      </body></html>

仅在getContext()中做了一点点改动，并在$.get()方法中设置返回类型。

ChatServlet:

package servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.Date;import java.util.Vector;import javassist.expr.Instanceof;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@SuppressWarnings("serial")public class ChatServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String args = request.getParameter("action");if(args.equals("get")){get(request, response);}else if(args.equals("send")){send(request, response);}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {            doGet(request, response);}  public void get(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{response.setContentType("text/html;charset=utf-8");response.setHeader("Cache-Control", "no-cache");PrintWriter out = response.getWriter();out.println("<?xml version = '1.0'?>");out.println("<chat>");ServletContext application = getServletContext();if(null != application.getAttribute("massage")){//@SuppressWarnings("unchecked")Vector<String> vec = (Vector<String>)application.getAttribute("massage");for (int i = vec.size() -1; i >= 0; i--) {out.println("<massage>"+vec.get(i) + "</massage>");}}else{out.println("<massage>欢迎光临阿文聊天室</massage>");}out.println("</chat>");out.flush();out.close();}@SuppressWarnings("unchecked")public void send(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{response.setContentType("text/html;charset=utf-8");        ServletContext application = getServletContext();String user = request.getParameter("user");String speak = request.getParameter("speak");String msg = "["+user+"]说："+speak;Vector<String> vec = (Vector<String>)application.getAttribute("massage");if(vec == null){vec = new Vector<String>();}vec.add(msg);application.setAttribute("massage", vec);//request.getRequestDispatcher("ChatServlet?action=get&nocache"+new Date().getTime()).forward(request, response);}}

仅在get方法中作出修改。

XML数据格式特点：可移植性和可重用性强，但是XML文档占据空间大，与其他文档格式相比，解析和操纵相对慢些。

3、返回JSON格式：JSON数组的使用

修改之处：1）、index.jsp页面

   function getContent(){      $.get("ChatServlet?action=get&nocache"+new Date().getTime(),function(data){      var msg = "";      var chats = eval(data); //eval()将字符串内容解析成js处理      $.each(chats,function(i){        msg += "<br>"+chats[i].massage;      });              $("#div1").html(msg);      },"JSON");   }

2）、ChatServlet中的get()函数

public void get(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{response.setContentType("text/html;charset=utf-8");response.setHeader("Cache-Control", "no-cache");PrintWriter out = response.getWriter();out.println("[");ServletContext application = getServletContext();String msg = "";if(null != application.getAttribute("massage")){//@SuppressWarnings("unchecked")Vector<String> vec = (Vector<String>)application.getAttribute("massage");for (int i = vec.size() -1; i >= 0; i--) {msg += "{\"massage\":\"" + vec.get(i) + "\"},";}out.println(msg.substring(0,msg.length()-1));}else{out.println("{\"massage\":"+"\"欢迎光临阿文聊天室！\"}");}out.println("]");out.flush();out.close();}

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