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php cookie 和session详解

2012-02-23 21:23  youxin  阅读(625)  评论(0)  编辑  收藏  举报

    先说cookie的用法。

 setcookie(name,value,int expire); 
  创建cookie，名字，值，过期时间一般是time()+(60*60*3) ，单位second
 
$_cookie['name']  //使用cookie
 
删除cookie，只要设置为过期就可以了
setcookie(name,value,time()-3600);
设置时间为过去的任何一个时候即可。
 
cookie是保存在客户端的，能够永久持续的，只要不过期。但是有些人设置浏览器禁用cookie，这是，application的功能对这些人可能不友好。
 
 
session是存储在服务器上的，浏览器不影响session的存储。因为存储在服务器端，所以session跟cookie相比更加安全和可信(secure and reliable).
session变量一旦会话结束后会自动销毁。
<?php
1. 开始一个session。 start a session
   session_start();  
 
2.   新建session变量
  $_SESSION['name']=value  
 
3，删除session变量。有两种变法
  1.unset($_SESSION['name']);  // 依次删除
  2.$_session=array() //删除所有的变量
 
4如果存在session的cookie，就删除
 if(isset($_COOKIE[session_name()])
{  setcookie(session_name(),' ', time()-3600);
}
setcookie(session_name(), '', time()-86400, '/');
 session在使用时可能会临时产生一个cookie来存储session id，session id是独一无二代表这个session的。 

This uses the function session_name() to get the name of the session dynamically, and
resets the session cookie to an empty string and to expire 24 hours ago (86400 is the number
of seconds in a day). The final argument ('/') applies the cookie to the whole domain

5.session_destroy(); 
 注意这个函数不删除任何变量，仅仅是关闭session。
<?php
// If the user is logged in, delete the session vars to log them out
session_start();
if (isset($_SESSION[‘user_id’]) ) {
// Delete the session vars by clearing the $_SESSION array
$_SESSION = array();
// Delete the session cookie by setting its expiration to an hour ago (3600)
s
if (isset($_COOKIE[session_name()])) {
etcookie(session_name(), ‘’, time() - 3600);
}
// Destroy the session
session_destroy();
}
// Redirect to the home page
$home_url = 'http://' . $_SERVER['HTTP_HOST'] . dirname($_SERVER['PHP_SELF']) . '/index.php';
header('Location: ' . $home_url);
?>
 
session官网解释如下：

session_start — Initialize session data

reject note Description

bool session_start ( void )

session_start() creates a session or resumes the current one based on a session identifier passed via a GET or POST request, or passed via a cookie.

To use a named session, call session_name() before calling session_start().

When session.use_trans_sid is enabled, the session_start() function will register an internal output handler for URL rewriting.

If a user uses ob_gzhandler or similar with ob_start(), the function order is important for proper output. For example, ob_gzhandler must be registered before starting the session.

reject note Return Values

This function returns TRUE if a session was successfully started, otherwise FALSE.

 

Note:

To use cookie-based sessions, session_start() must be called before outputing anything to the browser.
否则会有错误：
错误提示 
Warning: Cannot send session cookie - headers already sent 
Warning: Cannot send session cache limiter - headers already sent 
 
获取session的id值，
echo SID;
 
session_register()，此方法已经废弃 register . 登记；注册；记录one or more global vars with current session.
用法：
bool session_register ( mixed $name [, mixed $... ] )
<?php
// Use of session_register() is deprecated
$barney = "A big purple dinosaur.";
session_register("barney");

// Use of $_SESSION is preferred, as of PHP 4.1.0
$_SESSION["zim"] = "An invader from another planet.";

// The old way was to use $HTTP_SESSION_VARS
$HTTP_SESSION_VARS["spongebob"] = "He's got square pants.";
?>