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利用Servlet和jsp实现客户端与服务器端的用户登录信息验证

2011-12-03 00:06 891 查看

首先编写登录页面mylogin.jsp

编写表单：

<form onsubmit="return valdate()">

username:  <input type="text" name = "username" id="username"><br/>
password:  <input type="password" name = "password" id="password"><br/>
repassword:  <input type="password" name = "repassword" id="repassword"><br/>

<input type="submit" value="submit"/>
<input type="reset" value="reset"/>

</form>

第一种验证的方式：利用javascript在客户端实现验证

<script type="text/javascript">

function valdate(){
//var username = document.getElementById("username");
//var password = document.getElementById("password");
//var repassword = document.getElementById("repassword");

var username = document.getElementsByName("username")[0];
var password = document.getElementsByName("password")[0];
var repassword = document.getElementsByName("repassword")[0];

if(username.value.length == 0){

alert("username can not be blank");
return false;
}

if(password.value.length < 6 || password.value.length > 11){

alert("length of password is invalid");
return false;

}
if(password.value != repassword.value> 11){

alert("password is not the same with repassword");
return false;

}
return true;

}

</script>

如上面的代码所示，在表单中调用javascript的函数实现客户端验证。

第二种验证的方式：用Servlet实现验证

编写ValidateServlet.java类

package com.lcq.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@SuppressWarnings("serial")
public class ValidateServlet extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
String repassword = request.getParameter("repassword");
List<String> list = new ArrayList<String>();
if(null == username || "".equals(username)){
list.add("username can't be blank!");
}
if(password == null ||password.length() < 6 ||password.length() > 10){
list.add("length of password should be between 6 and 10");
}
if(repassword == null ||repassword.length() < 6 || repassword.length() > 10){
list.add("length of repassword should be between 6 and 10");
}
if(password != null && repassword != null && !password.equals(repassword)){
list.add("password and repassword not the same!");
}

if(list.isEmpty()){
request.setAttribute("username", username);
request.setAttribute("password", password);
request.getRequestDispatcher("sucess.jsp").forward(request, response);
}else{
request.setAttribute("error",list);
request.getRequestDispatcher("error.jsp").forward(request, response);;
}

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

}

}

在Servlet中处理完成后转到sucess.jsp或者error.jsp

以下是sucess.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>

<title>My JSP 'sucess.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->

</head>

<body>

username :<%=request.getAttribute("username") %><br>
password :<%=request.getAttribute("password") %>

</body>
</html>

以下是error.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>

<title>My JSP 'error.jsp' starting page</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">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->

</head>

<body>

<h1>login failed:</h1>
<%
List <String> list = (List<String>)request.getAttribute("error");
for(String str : list ){
out.println(str + "<br>");

}
%>

</body>
</html>

用第二种方式时将mylogin.jsp中的表单修改为

<form action="ValidateServlet">

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标签： servlet jsp 服务器 stylesheet string input

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