Ajax中利用jQuery简单实现异步交互

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function verify(){//alert("被点击了。。。。。。。");//得到id为loginName的标签对象var jqObject = $("#loginName");//得到文本框中的值var name = jqObject.val();//用JQ中的$.get()方法去访问服务器/*JQ中的get方法接受的参数 * get(url, [data], [callback], [type]) * url 待载入页面的URL地址 * data (可选) 待发送 Key/value 参数。 * callback (可选) 载入成功时回调函数。 * type (可选) 返回内容格式，xml, html, script, json, text, _default。 */$.get("AjaxTestServlet?loginName=" + name,null,callback);}//从服务器返回来的数据封装在callback函数的参数中function callback(data){alert(data);}

主页html为如下

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=GBK"><title>Insert title here</title><script type="text/javascript" src="jquery-1.7.1.js"></script><script type="text/javascript" src="verify.js"></script></head><body><form name="form1" action="AjaxTestServlet" method="POST">请输入注册用户名： <input name="loginName" type="text" id="loginName"><input type="button" name="checkLoginName" value="有效性检查"onclick="verify()"><br></form></body></html>

接受的响应的服务器端的程序为AjaxTestServlet

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * Servlet implementation class AjaxTestServlet */@WebServlet("/AjaxTestServlet")public class AjaxTestServlet extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public AjaxTestServlet() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoPost(request,response);}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// post按doGet()方法处理response.setContentType("text/html");PrintWriter out = response.getWriter();//这里假设已经注册过了四位用户String[] logined = {"admin","users","dywdyw","zhaom_916"};//接收从客户端提交的loginName参数String loginName = request.getParameter("loginName");//创建一个存放响应内容的字符串String responseContext = "true";for (int i=0;i<logined.length;i++){//遍历已注册用户列表，如果发现提交的注册名已存在，则修改响应内容if (loginName.equals(logined[i]))responseContext = "false";}//将处理结果返回给客户端out.println(responseContext);out.flush();out.close();}}

中间遇到过一个小问题就是要求js与html的编码一致不然会出现乱码