服务器端也就是sevlet,都能执行，out.print();也可以输出字符串，但就是xmlhttprequest.responseText为啥不执行!
<%@ page language="java" contentType="text/html; charset=utf-8"%>
<!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=utf-8">
<script type="text/javascript" language="javascript">
window.onload=function(){
var XMLHttpReq=new XMLHttpRequest();
document.getElementById("i_email").onblur=function(){
var username=document.getElementById("i_email").value;
var password=document.getElementById("password").value;
XMLHttpReq.onreadystatechange=function(){
if(XMLHttpReq.readyState==4){
if(XMLHttpReq.status==200){
alert("http协议成功！");
var xhr=XMLHttpReq.responseText();
alert("sdf");
alert(XMLHttpReq.responseText());
if(server_value=="no_user"){
alert("无此用户名");
document.getElementById("message").innerHTML="无此用户名！";
}
if(server_value.equals("true")){
alert("密码错误");
document.getElementById("message").innerHTML="密码错误！";
}
}
}
};
XMLHttpReq.open("get","com.servlet/Login_servlet?username="+username+"&password="+password,true);
XMLHttpReq.send();
};
};
</script>
<link rel="stylesheet" type="text/css" href="css/css.css">
<title>登录页面</title>
</head>
<body>
<div class="logo">
<div class="comwidth">
<a><img alt="返回主页" src="image/首页.gif"></a>
<h3>欢迎登录</h3>
</div>
</div>
<div class="land comwidth" >
<form action="com.servlet/Login_servlet" method="post" name="login_form">
<ul>
<li class="email"><label>邮箱/用户/手机号</label></li>
<li><input type="text" class="i_email" id="i_email" name="username" ></li>
<li class="ps"><label>密码</label></li>
<li><input type="password" class="password" name="password" id="password"></li>
<li class="auto_login">
<input type="checkbox" class="auto_login"><label>自动登录</label>
<input type="checkbox" class="safe_login"><label>安全控件登录</label>
<span> 忘记密码?</span></li>
<li class="message"><label id="message"> </label></li>
<li><input type="submit" value="登录" class="login_btn" ></li>
<li class="other"><label>使用合作网站登录</label></li>
<li class="other1"><a href="#">QQ</a>|<a href="#">新浪</a>|<a href="#">淘宝</a>|<a href="#">网易</a>|<a href="#">更多>></a></li>
</ul>
</form>
</div>
<div class="register comwidth"><a href="register.jsp"><input class="register_btn" type="button" value="免费注册>>"></a></div>
<div class="copyright">
<div class="copyright_1"><p> <a href="#">网站简介</a>|<a href="#">网站公告</a>| <a href="# ">招纳贤士</a>| <a href="#">联系我们</a>|客服热线：400-675-1234
</p>
<p>Copyright © 2006 - 2014 网站版权所有 京ICP备09037834号 京ICP证B1034-8373号 某市公安局XX分局备案编号：123456789123</p>
</div>
<div class="copyright_2">
<ul class="copyright_ul">
<li><a href=""><img src="image/7.gif"></a></li>
<li><a href=""><img src="image/7.gif"></a></li>
<li><a href=""><img src="image/7.gif"></a></li>
<li><a href=""><img src="image/7.gif"></a></li>
</ul>
</div>
</div>
</body>
</html>
这是severlet，也就是服务器端的
package com.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.wjn.Connect;
import com.wjn.User;
@WebServlet("/Login_servlet")
public class Login_servlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public Login_servlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String user=request.getParameter("username");
String password=request.getParameter("password");
String flag=null;
User s=new User();
s.setName(user);s.setPassword(password);
/*System.out.println("用户名"+user);
System.out.println("密码"+password);*/
String sql_user=" SELECT * FROM [User] WHERE user1=? ";
String sql_password=" SELECT * FROM [User] WHERE user1=? AND password=? ";
Connection con=Connect.getConnection();
ResultSet rs_user = null;
ResultSet rs_password = null;
try {
PrintWriter out = response.getWriter();
PreparedStatement prs=con.prepareStatement(sql_user);
prs.setString(1,s.getName());
prs.execute();
rs_user=(ResultSet)prs.executeQuery();
/*判断是否有此用户名*/
if(rs_user.next()){
PreparedStatement prs_password=con.prepareStatement(sql_password);
prs_password.setString(1,s.getName());
prs_password.setString(2,s.getPassword());
prs_password.execute();
rs_password=(ResultSet)prs_password.executeQuery();
if(rs_password.next()){
HttpSession session = request.getSession();
session.setAttribute("User", user);
response.sendRedirect(request.getContextPath()+"/success.jsp");
}
else{
flag="fail";
System.out.println(flag);
}
}
/*无此用户名*/
else{
flag="no_user";
System.out.println("无此用户名"+flag);
}
out.print(flag);
out.flush();
out.close();
System.out.println(flag);
}
catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
