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jsp 通过 Ajax 和servlet之间的连接及数据传递示例

2013-12-10 14:51 555 查看
效果图：很基本的例子，不过刚开始把第三步open（）连接中url 写错了，老是访问不到，如果出现相同的问题，可以再js部分第二步中通过alert（“xmlReq.readystate=”+xmlReq+" "+"xmlReq.status="+xmlReq.status）;来调试错误地方jsp代码：
<%@ 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>Register</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">

<script type="text/javascript" src="./register/Register.js"></script>
</head>

<body>
	<form action="" enctype="application/x-www-form-urlencoded">
		<table border="1">
			<tr>
				<td colspan="2" align="center"><Strong>用户注册</Strong>
				</td>
			</tr>
			<tr>
				<td>用户名：</td>
				<td><input type="text" id="username">
					<div id="divcheck"></div>
			</tr>
			<tr>
				<td>密  码：</td>
				<td><input type="password" id="password"></td>
			</tr>
			<tr>
				<td><input type="button" value="验证" id="checkusername">
				</td>
				<td align="center"><input type="reset" value="重置">
				</td>
			</tr>
			<!-- <tr>
				<td><a href="javascript:;" onclick="find()" id="1"
					value="100">平台简介</a></td>
				<td><a>开放业务</a>
				</td>
			</tr> -->
		</table>
	</form>
</body>
</html>
js代码
//创建XMLHttpRequest 对象的函数
function ajaxFunction() {
	var xmlHttp;
	try {// Firefox,Opera,Safari
		xmlHttp = new XMLHttpRequest();
	} catch (e) {// Internet Explorer
		try {
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {
			}
		}

	}
	return xmlHttp;
}

window.onload = function() {
	document.getElementById("checkusername").onclick = function() {
		var username = document.getElementById("username").value;
		// 1创建xmlHTTP对象
		var xmlReq = ajaxFunction();
		/**
		 * 2、处理服务器端的响应 readyState的值为4代表响应完成 status属性：200代表一切正常；304代表源文件没有别修改
		 * 404代表找不到页面；403禁止访问； 500 内部服务器错误
		 * 
		 */
		xmlReq.onreadystatechange = function() {
			if (xmlReq.readyState == 4) {
				if (xmlReq.status == 200 || xmlReq.status == 304) {
					var data = xmlReq.responseText;
					document.getElementById("divcheck").innerHTML = data;
				}
			}
		};

		// 3、打开和服务器端的连接 如果是get方法，则改为get并且删掉第二条语句
		var url = "./servlet/registServlet";
		xmlReq.open("post", url, true);
		xmlReq.setRequestHeader("Content-Type",
				"application/x-www-form-urlencoded");
		// 4、get 方法不会接受到，这里只适合于post方法传递参数
		xmlReq.send("username=" + username);
	};
};
servlet代码：
package cn.servlet;

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 registServlet extends HttpServlet {

	private static final long serialVersionUID = -2968705132907930725L;

	public registServlet() {
		super();
	}

	public void destroy() {
		super.destroy();

	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		String username = request.getParameter("username");
		if ("admin".equals(username)) {
			out.println("用户名已存在~");
		} else {
			out.println("用户名可用~");
		}
	}

	public void init() throws ServletException {
	}

}

                                            

                                        

                        
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