PHP中Cookie的作用域问题
2008-5-23 14:55 一直都想当然的以为Cookie的作用域是根目录，并且还时常给别人说就是这样的，直到最近在集成PHPMyVisits的时候吃了大亏才把它弄明白了，汗，希望被我毒害的人不要找我麻烦。
PHPMyVisits用的是单入口模式，Cookie登录验证，但是我自己在写API的时候老是有问题，把API放在根目录就是好好的，放到二级目录就有问题，而UCenter又要求API必须放到api目录下，搞了一天都没有搞清楚问题出在哪，还一段一段的去调试代码，又忙又郁闷。
今天写了个测试代码，分别放到根目录和api的目录，查看cookie的生成情况，才发现两个目录下相同的代码读出的cookie竟然不同，于是意识到问题是出在cookie的路径身上了，再一查手册，果然如此，人家cookie默认的作用域明明就是程序所在的目录！另外Cookies不会在设置它的本页生效，要测试一个 cookie 是否被成功的设定，可以在其到期之前通过另外一个页面来访问其值。
以下是PHP Manual的说明:
Description
setcookie() defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including <html> and <head> tags as well as any whitespace.
Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE or $HTTP_COOKIE_VARS arrays. Note, superglobals such as $_COOKIE became available in PHP 4.1.0. Cookie values also exist in $_REQUEST.
Parameters
All the arguments except the name argument are optional. You may also replace an argument with an empty string ("") in order to skip that argument. Because the expire argument is integer, it cannot be skipped with an empty string, use a zero (0) instead.
See » Netscape cookie specification for specifics on how each setcookie() parameter works
- name
-
The name of the cookie.
- value
-
The value of the cookie. This value is stored on the clients computer; do not store sensitive information. Assuming the name is ‘cookiename’, this value is retrieved through $_COOKIE['cookiename']
- expire
-
The time the cookie expires. This is a Unix timestamp so is in number of seconds since the epoch. In other words, you’ll most likely set this with the time() function plus the number of seconds before you want it to expire. Or you might use mktime(). time()+60*60*24*30 will set the cookie to expire in 30 days. If set to 0, or omitted, the cookie will expire at the end of the session (when the browser closes).
Note: You may notice the expire parameter takes on a Unix timestamp, as opposed to the date format Wdy, DD-Mon-YYYY HH:MM:SS GMT, this is because PHP does this conversion internally.
expire is compared to the client’s time which can differ from server’s time. - path
-
The path on the server in which the cookie will be available on. If set to ‘/’, the cookie will be available within the entire domain . If set to ‘/foo/’, the cookie will only be available within the /foo/ directory and all sub-directories such as /foo/bar/ of domain . The default value is the current directory that the cookie is being set in.
- domain
-
The domain that the cookie is available. To make the cookie available on all subdomains of example.com then you’d set it to ‘.example.com’. The . is not required but makes it compatible with more browsers. Setting it to www.example.com will make the cookie only available in the www subdomain. Refer to tail matching in the » spec for details.
- secure
-
Indicates that the cookie should only be transmitted over a secure HTTPS connection from the client. When set to TRUE, the cookie will only be set if a secure connection exists. The default is FALSE. On the server-side, it’s on the programmer to send this kind of cookie only on secure connection (e.g. with respect to $_SERVER["HTTPS"]).
- httponly
-
When TRUE the cookie will be made accessible only through the HTTP protocol. This means that the cookie won’t be accessible by scripting languages, such as JavaScript. This setting can effectly help to reduce identity theft through XSS attacks (although it is not supported by all browsers). Added in PHP 5.2.0. TRUE or FALSE
Return Values
If output exists prior to calling this function, setcookie() will fail and return FALSE. If setcookie() successfully runs, it will return TRUE. This does not indicate whether the user accepted the cookie.
