原理: 登陆界面为login.html, 提交表单跳转到login.php页面, 通过验证后跳转到index.php, 退出时跳转到logout.php.
1.login.html
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/>
<title>会员登录</title>
<style type="text/css">
ul li{margin:0;padding:0;}
form{margin:40px 30px 0;}
form li{list-style:none;padding:5px 0;}
form li label{float:left;width:70px;text-align:right}
form li a{font-size:12px;color:#999;text-decoration:none}
.login_btn{border:none;background:#01A4F1;color:#fff;font-size:14px;font-weight:bold;height:28px;line-height:28px;padding:0 10px;cursor:pointer;}
form li img{vertical-align:top}
</style>
</head>
<body>
<form action="login.php" method="POST">
<fieldset>
<legend>用户登录</legend>
<ul>
<li>
<label for"">用户名:</label>
<input type="text" name="username"/>
</li>
<li>
<label for"">密码:</label>
<input type="password" name="password"/>
</li>
<li>
<label for""> </label>
<input type="submit" name="login" value="登录" class="login_btn"/>
</li>
</ul>
</fieldset>
</body>
</html>
2.index.php
<?php
header("Content-Type:text/html;charset=utf-8");
session_start();
if(isset($_POST['login']))
{
$username = trim($_POST['username']);
$password = trim($_POST['password']);
if(($username=='')||($password==''))
{
header('refresh:3;url=login.html');
echo "改用户名或密码不能为空，3秒后跳转到登录页面";
exit;
}
else if(($username!='username')||($password!='password'))
{
//用户名或密码错误
header('refresh:3;url=login.html');
echo "用户名或密码错误，3秒后跳转到登录页面";
exit;
}
else if(($username=='username')&&($password=='password'))
{
//登录成功将信息保存到session中
$_SESSION['username']=$username;
$_SESSION['islogin']=1;
//如果勾选7天内自动保存，则将其保存到cookie
if($_POST['remember']=="yes")
{
setcookie("username",$username,time()+7*24*60*60);
setcookie("code",md5($username.md5($password)),time()+7*24*60*60);
}
else
{
setcookie("username",'',time()-1);
setcookie("code",'',time()-1);
}
//跳转到用户首页
header('refresh:3;url=index.php');
}
}
?>
3.index.php
<?php
header("Content-Type:text/html;charset=utf-8");
session_start();
//首先判断Cookie是否有记住用户信息
if(isset($_COOKIE['username']))
{
$_SESSION['username']=$_COOKIE['username'];
$_SESSION['islogin']=1;
}
if(isset($_SESSION['islogin']))
{
//已经登录
echo $_SESSION['username'].":你好，欢迎进入个人中心！<br/>";
echo "<a href='logout.php'>注销</a>";
}
else
{
//未登录
echo "你还未登录，请<a href='login.html'>登录</a>";
}
?>
4.logout.php
<?php
header("Content-Type:text/html;charset=utf-8");
session_start();
//清除session
$username=$_SESSION['username'];
$_SESSION=array();
session_destroy();
//清除cookie
setcookie("username",'',time()-1);
setcookie("code",'',time()-1);
echo "$username,欢迎下次光临";
echo "重新<a href='login.html'>登录</a>";
?>
