使用AJAX（包含正则表达式）验证用户登录的步骤

我们来分一下步骤吧：

1.HTML代码，页面先写出来；

2.正则表达式验证输入的用户名密码是否正确，失去焦点验证

3.Ajax异步提交

4.servlet这是后台处理代码获取数据并对比响应，然后跳转成功页面

效果图：

结构：

代码如下：

%@ page language="java" import="java.util.*" pageEncoding="utf-8"%
!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
html
head
script type="text/javascript" src="JS/jQuery.js"/script
style type="text/css"
table {
 width: 360px;
 height: 45px: 
 text-align: center;
 margin-top: 120px;
 border-collapse: collapse;
}

input {
 width: 280px;
 height: 30px;
}
/style
/head
body
 form action="#" method="post"
 center
 table align="center" border="1"
 tr
  td用户名:/td
  tdinput type="text" name="name" id="username"
  onblur="verifyName()" //td
 /tr
 tr
  td密码:/td
  tdinput type="text" name="pwd" id="mypwd"
  onblur="verifyPwd()" //td
 /tr
 tr
  td colspan="3" align="center" height="36px"input
  type="button" style="width: 8rem;height:27px" value="提交登录验证" //td
 /tr
 /table
 /center
 /form
 script type="text/javascript"
 function verifyName() {
 //用户名校验
 var verifyName = document.getElementById("username").value;
 var name = /^[A-Z][0-9A-Za-z_][a-zA-Z0-9_]{5,19}$/; // 大写字母开头 6-20位字符(不允许有符号但是允许有_)
 if (!name.test(verifyName)) {
 //$("#username").after("span大写字母开头6-20位字符(不允许有符号但是允许有_)/span");
 $("#username").css("border-color", "red");
 return false;
 } else {
 return true;
 }
 }
 function verifyPwd() {
 //密码
 var verifyPwd = document.getElementById("mypwd").value;
 var pwd = /^[A-Z][A-Za-z0-9]w{7,14}.{1,20}$/; //大写开头 数字字母符号混合 8-15位
 if (!pwd.test(verifyPwd)) {
 $("#username").css("border-color", "red");
 return false;
 } else {
 return true;
 }
 }
 
 $(function() {
 $(":button").on("click", function() {
 $.ajax({
  type : "post",
  url : "AJAXServlet",
  data : {
  name : $("#username").val(),
  pwd : $("#mypwd").val()
  },
  dataType : "text",
  success : function(data) {
  if (data == "ok") {
  window.location.href = "show.jsp";
  } else {
  alert("登录失败！");
  $("#mypwd").val("");
  $("#username").focus().select();
  }
  }
 });
 });
 });
 /script
/body
/html

servlet代码：

package com.chaz.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 AJAXServlet extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 doPost(request, response);
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 response.setContentType("text/html;charset=utf-8");
 request.setCharacterEncoding("utf-8");
 PrintWriter out = response.getWriter();
 
 String name = "ZhangSan";
 String pwd = "Zhang123456";
 
 String ajaxName = request.getParameter("name");
 String ajaxPwd = request.getParameter("pwd");
 System.out.println(ajaxName+":"+ajaxPwd);
 if(name.equals(ajaxName)pwd.equals(ajaxPwd)){
 out.print("ok");
 }else{
 out.print("Error");
 }
 out.flush();
 out.close();
 }
}

web.xml:

xml version="1.0" encoding="UTF-8"
web-app version="3.0"
 xmlns="http://java.***sun.com/xml/ns/javaee"
 xmlns:xsi="http://www.***w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.***sun.com/xml/ns/javaee http://java.***sun.com/xml/ns/javaee/web-app_3_0.xsd"
 servlet
 descriptionThis is the description of my J2EE component/description
 display-nameThis is the display name of my J2EE component/display-name
 servlet-nameAJAXServlet/servlet-name
 servlet-classcom.chaz.servlet.AJAXServlet/servlet-class
 /servlet

 servlet-mapping
 servlet-nameAJAXServlet/servlet-name
 url-pattern/AJAXServlet/url-pattern
 /servlet-mapping

/web-app

跳转成功页面就这个：

body 登录成功！/body

总结