使用AJAX实现Web页面进度条的实例分享_javascript技巧

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %> 
<%! 
int counter = 1;//注意：多用户将共享此变量，此进度条只适合单用户 
%> 
<% 
 String task = request.getParameter("task"); 
  String res = ""; 
   
  if (task.equals("create")) { 
   res = "1"; 
   counter = 1; 
  } 
  else { 
   String percent = ""; 
   switch (counter) { 
    case 1: percent = "10"; break; 
    case 2: percent = "23"; break; 
    case 3: percent = "35"; break; 
    case 4: percent = "51"; break; 
    case 5: percent = "64"; break; 
    case 6: percent = "73"; break; 
    case 7: percent = "89"; break; 
    case 8: percent = "100"; break; 
   } 
   counter++; 
     
   res = "" + percent + ""; 
  } 
   
  // PrintWriter out = response.getWriter(); 
  response.setContentType("text/xml"); 
  response.setHeader("Cache-Control", "no-cache"); 
  out.println(""); 
  out.println(res); 
  out.println(""); 
  out.close();  
%> 

将上述代码保存，名称为ProgressBar.jsp。在该文件中，声明了一个变量counter，并赋值为1，该变量是进度条返回百分比数字的依据。在下面使用request对象获取客户端传送的变量task的值，如果该值为create，表示需要重新创建进度条，并设定counter的值为1；如果task不是create，则会依据counter的值返回百分比数字，完成一次操作，counter值加1。

2，客户端代码
本实例的客户端代码主要实现依据返回百分比数字显示进度条的状态。打开记事本，输入下列代码：