今天无意间看见一个这样的AJAX例子，觉得很有价值，于是便记录了下来，以供以后参考。
原文地址：
http://hi.baidu.com/casa2/blog/item/7a6bc1c684e81c1f9d163df5.html
本例将在页面的参数以Get和POST两种方式传递到服务器，并回显到页面；
本例共包括两个主要文件getAndPostExample.html和GetAndPostExample.java以及一个配置文件web.xml
建立文件的步骤：
1.在Eclipse新建一个web project-->ajax1
2.在ajax1里面新建一个getAndPostExample.html
3.在ajax1里面新建一个servlet-->GetAndPostExample.java
getAndPostExample.html如下
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>getAndPostExamplel.html</title>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
<script type="text/javascript">
var xmlHttp;
//创建XMLhttpRequest对象
function createXMLHttpRequest() {
if (window.ActiveXObject) {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
else if (window.XMLHttpRequest) {
xmlHttp = new XMLHttpRequest();
}
}
//生成传递到服务器的参数查询串，参数值由页面表单填写得到
function createQueryString() {
var firstName = document.getElementById("firstName").value;
var middleName = document.getElementById("middleName").value;
var birthday = document.getElementById("birthday").value;
var queryString = "firstName=" + firstName + "&middleName=" + middleName
+ "&birthday=" + birthday;
return queryString;
}
//点击按钮响应的Get方法主函数
//Get方法把参数值以名=值方式在xmlHttp.open("GET", queryString, true)中传递,queryString的形式为URL?参数名=值&参数名=值...;而xmlHttp.send(null);
function doRequestUsingGET() {
createXMLHttpRequest();//第一步：创建XMLHttpRequest对象
var queryString = "GetAndPostExample?";
queryString = queryString + createQueryString()
+ "&timeStamp=" + new Date().getTime();//第二步：定义传递的参数值字符串
xmlHttp.open("GET", queryString, true);//第三步：建立与服务器的请求
xmlHttp.onreadystatechange = handleStateChange;//第四步：监听状态-->转到监听状态函数
xmlHttp.send(null);//第五步：发送请求，并且立即返回
}
//点击按钮响应的POST方法主函数
//POST方法把参数值以名=值方式在xmlHttp.send(queryString)中传递,queryString的形式为参数名=值&参数名=值...;
function doRequestUsingPOST() {
createXMLHttpRequest();//第一步：创建XMLHttpRequest对象
var url = "GetAndPostExample?timeStamp=" + new Date().getTime();
var queryString = createQueryString();//第二步：定义传递的参数值字符串
xmlHttp.open("POST", url, true);//第三步：建立与服务器的请求
xmlHttp.onreadystatechange = handleStateChange;//第四步：监听状态-->转到监听状态函数
xmlHttp.setRequestHeader("Content-Type",
"application/x-www-form-urlencoded;");
xmlHttp.send(queryString);//第五步：发送请求，并且立即返回
}
//监听状态函数
function handleStateChange() {
if(xmlHttp.readyState == 4) {
if(xmlHttp.status == 200) {
parseResults();//-->转到函数parseResults输出从服务器返的值
}
}
}
//在页面显示从服务器传来的结果
function parseResults() {
var responseDiv = document.getElementById("serverResponse");
if(responseDiv.hasChildNodes()) {
responseDiv.removeChild(responseDiv.childNodes[0]);
}
var responseText = document.createTextNode(xmlHttp.responseText);//
responseDiv.appendChild(responseText);
}
</script>
</head>
<body>
<h1>Enter your first name, middle name, and birthday:</h1>
<table>
<tbody>
<tr>
<td>First name:</td>
<td><input type="text" id="firstName"/>
</tr>
<tr>
<td>Middle name:</td>
<td><input type="text" id="middleName"/>
</tr>
<tr>
<td>Birthday:</td>
<td><input type="text" id="birthday"/>
</tr>
</tbody>
</table>
<form action="#">
<input type="button" value="Send parameters using GET"
onclick="doRequestUsingGET();"/><!--调用Get方法主函数-->
<br/><br/>
<input type="button" value="Send parameters using POST"
onclick="doRequestUsingPOST();"/><!--调用POST方法主函数-->
</form>
<br/>
<h2>Server Response:</h2>
<div id="serverResponse"></div>
</body>
</html>
GetAndPostExample.java 如下
package com.ajax1;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class GetAndPostExample extends HttpServlet {
protected void processRequest(HttpServletRequest request,
HttpServletResponse response, String method)
throws ServletException, IOException {
//把响应内容类型设置为 text/xml
response.setContentType("text/xml");
//得到用户参数值
String firstName = request.getParameter("firstName");
String middleName = request.getParameter("middleName");
String birthday = request.getParameter("birthday");
//生成包含用户参数值的返回字符串
String responseText = "Hello " + firstName + " " + middleName
+ ". Your birthday is " + birthday + "."
+ " [Method: " + method + "]";
//写回浏览器
PrintWriter out = response.getWriter();
out.println(responseText);
out.close();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//Get主函数调用processRequest,完成Get方法的参数接受，返回的过程
processRequest(request, response, "GET");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//POST主函数调用processRequest,完成POST方法的参数接受，返回的过程
processRequest(request, response, "POST");
}
}
web.xml 如下
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>GetAndPostExample</servlet-name>
<servlet-class>com.ajax1.GetAndPostExample</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>GetAndPostExample</servlet-name>
<url-pattern>/GetAndPostExample</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
在这个简单的AJAX的例子里getAndPostExaple.html负责表单参数的输入和传递，而servlet GetAndPostExample.java负责在服务器端接受参数。参数传递时加的时间戳是保证URL的唯一性。
posted on 2008-04-21 12:22
biiau 阅读(5828)
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