php session 登录退出验证

login.html 负责收集用户填写的登录信息

登录处理login.php 负责处理用户登录与退出动作

<?php
header("Content-Type:text/html;charset=utf-8");
if(!isset($_POST['submit'])){
exit('非法访问!');
}
$username = htmlspecialchars($_POST['username']);
$password = MD5($_POST['password']);

//包含数据库连接文件
include('conn.php');
//检测用户名及密码是否正确
$check_query = mysql_query("select uid from user where username='$username' and password='$password' limit 1");
if($result = mysql_fetch_array($check_query)){
//登录成功
$_SESSION['username'] = $username;
echo $username,' 欢迎你！进入 <a href="my.php">用户中心</a><br />';
echo '点击此处 <a href="login.php?action=logout">注销</a> 登录！<br />';
exit;
} else {
exit('登录失败！点击此处 <a href="javascript:history.back(-1);">返回</a> 重试');
}
退出处理处理用户退出的代码跟处理登录的代码都在 login.php 里。 session_start();

//注销登录
if($_GET['action'] == "logout"){
unset($_SESSION['username']);
echo '注销登录成功！点击此处 <a href="login.html">登录</a>';
exit;
}
?>

my.php

<?php
header("Content-Type:text/html;charset=utf-8");
session_start();
//检测是否登录，若没登录则转向登录界面
if(!isset($_SESSION['userid'])){
header("Location:login.html");
exit();
}
//包含数据库连接文件
include('conn.php');
$userid = $_SESSION['userid'];
$username = $_SESSION['username'];
$user_query = mysql_query("select * from user where uid=$userid limit 1");
$row = mysql_fetch_array($user_query);
echo '用户信息：<br />';
echo '用户ID：'.$userid.'<br />';
echo '用户名：'.$username.'<br />';
echo '<a href="login.php?action=logout">注销</a> 登录<br />';
?>