AJAX登陆实例!
index.jsp文件:<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><html><head><script> //设一个变量 var XMLHttpReq=false; //创建一个XMLHttpRequest对象 function createXMLHttpRequest(){ if(window.XMLHttpRequest){ //MozillaXMLHttpReq=new XMLHttpRequest(); } else if(window.ActiveXObject){ try{ XMLHttpReq=new ActiveXObject("Msxml2.XMLHTTP"); }catch(e){ try{ XMLHttpReq=new ActiveXObject("Microsoft.XMLHTTP"); }catch(e){} } } } //发送请求函数 function send(url){ createXMLHttpRequest(); XMLHttpReq.open("GET",url,true); XMLHttpReq.onreadystatechange=proce; //指定响应的函数 XMLHttpReq.send(null);//发送请求 } function proce(){ if(XMLHttpReq.readyState==4){ //对象状态 if(XMLHttpReq.status==200){//信息已成功返回，开始处理信息 var res=XMLHttpReq.responseXML.getElementsByTagName("content").firstChild.data; window.alert(res); }else{ window.alert("所请求的页面有异常"); } } } //身份验证function check(){ var name=document.getElementById("name").value;if(name==""){ alert("请输入内容"); return false; } else{ send('login?name='+name); } }</script></head><body> <form action="login" method="post"> <tr><td>姓名: <input id="name" type="text" name="name"/> <input type="button" value="检测" /> </td> </tr> </form> </body></html>TestA.java这是一个Servlet文件:
package tt;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 TestA extends HttpServlet {protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {request.setCharacterEncoding("utf-8");String name=request.getParameter("name");response.setContentType("text/xml; charset=utf-8");response.setHeader("Cache-Control","no-cache");PrintWriter out=response.getWriter();out.println("<pront>");if(name.equals("and4walker")){out.println("<content>"+"对不起,此名已经注册"+"</content>");}else{out.println("<content>"+"可以注册"+"</content>");}out.println("</pront>");out.close();}}
web.xml文件:
<?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><servlet-name>login</servlet-name><servlet-class>tt.TestA</servlet-class></servlet><servlet-mapping><servlet-name>login</servlet-name><url-pattern>/login</url-pattern></servlet-mapping></web-app>
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