一：功能要求
页面进行ajax提交的时候，在服务端未响应的时间内，页面出现“正在加载”的文字提示，告诉用户他的请求已得到响应，得到服务端响应后，提示关闭不显示。
二：代码
1.首先是web页面：
当点击ID未span_1的文字后。发送一个get请求。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Loading demo</title>
<script src="jquery-1.2.1.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function() {
$("#span_1").click(function() {
//alert("click");
$.get("Faq",{id:1}, function(xml){
var text = $("Response", xml).text();
$("#div_1").html(text);
});
});
$("#loading").ajaxStart(function(){
//alert("start");
//$(this).html("<img src=loading.gif> 正在加载");
$(this).css("display", "block");
});
$("#loading").ajaxSuccess(function(){
//alert("end");
//$(this).html("加载完成!");
$(this).css("display", "none");
});
});
</script>
</head>
<body>
<div id="faq">
<span id="span_1">什么是jquery?</span>
<div id="div_1"></div>
</div>
<div id="loading" style="display:none"><img src=loading.gif> 正在加载</div>
</body>
</html>
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2.服务端
服务端是一个servlet，随即显示一段文字。
package com.hexin.ajax;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Faq extends HttpServlet {
private final String XML_HEAD = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
/**
* Constructor of the object.
*/
public Faq() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("开始执行");
response.setContentType("text/xml");
response.setHeader("Cache-Control", "no-cache");
response.setCharacterEncoding("UTF-8");//设置utf-8j解决乱码问题
PrintWriter out = response.getWriter();
out.print(XML_HEAD);
Random random = new Random(System.currentTimeMillis());
if(random.nextBoolean()){
out.println("<Response>论坛版主用户可以根据自己的特长喜好自愿申请，申请版主的用户应该是累积经验值达到1000分，威望值达到20以上的注册用户。版主需要承担相应的版面发展职责，并愿意为其他用户服务。</Response>");
System.out.println("至个人信息管理中心可以进行基本信息管理、社区管理与论坛管理，可以查看短消息、整理个人收藏、查看个人主题，直接点击页面右侧相关链接即可。");
}else{
out.println("<Response>论坛版主用户可以根据自己的特长喜好自愿申请，申请版主的用户应该是累积经验值达到1000分，威望值达到20以上的注册用户。版主需要承担相应的版面发展职责，并愿意为其他用户服务。</Response>");
System.out.println("论坛版主用户可以根据自己的特长喜好自愿申请，申请版主的用户应该是累积经验值达到1000分，威望值达到20以上的注册用户。版主需要承担相应的版面发展职责，并愿意为其他用户服务。");
}
out.flush();
out.close();
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occure
*/
public void init() throws ServletException {
// Put your code here
}
}
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文章来源:
http://huxiaofei590.blog.163.com/blog/static/32596122007111441412585