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ObjectiveReprint please indicate the source:
http://blog.csdn.net/hai_qing_xu_kong/article/details/51922536
This article is from: "Gu Linhai's Blog"
It's been one or two weeks since blogging, and it's been a busy time to get familiar with the project in a new company that's ready to start in some channels, so it takes a lot of time to fix bugs and add features. Well, continue with the topic of this chapter.
Cookie ManagementA cookie is a mechanism for storing data on a remote browser to track and identify users. Simply put, a cookie is a text file that the Web server temporarily stores on the user's hard disk and is then read by the Web browser. When the user visits the Web site again, the website will respond quickly by reading the cookie file to record the visitor's specific information (such as the location of the last visit, time spent, user name and password, etc.), for example, if you do not need to enter the user's ID and password on the page to login directly to the website.
The command format for the text file is as follows:
用户名@网站地址[数字].txt
The Web server can apply cookies to contain information about the arbitrariness to filter and regularly maintain this information in order to determine the status in the HTTP transmission. Cookies are commonly used in the following 3 areas:
Create a cookie in PHP with the Setcookie () function. The syntax format is as follows:
bool setcookie(string name[,stringvalue[,intstring path[,string domain[,int secure]]]]])
| Parameters | Description | Example |
|---|---|---|
| Name | Variable name of the cookie | You can call a COOKIE with the variable named CookieName by $_cookie["CookieName") |
| Value | The value of the cookie variable, which is stored on the client and cannot be used to hold sensitive data | A value named values can be obtained by $_cookie["values" |
| Expire | The expiration time of the cookie, expire is the standard UNIX time tag, which can be obtained in seconds () or the Mktime () function. | If you do not set a cookie's expiration time, the cookie will always work, unless you manually delete it |
| Path | Valid path of cookie on server side | If the parameter is set to "/", it is valid throughout domain and, if set to "/11", it is valid in the/11 directory and subdirectories under domain. The default is the current directory |
| Domain | A valid domain name for cookies | If you want the cookie to be valid for all subdomains under the hhh.com domain name, it should be set to hhh.com |
| Secure | Indicates whether the cookie is only secured by HTTPS with a value of 0 or 1 | If the value is 1, the cookie is valid only on HTTPS connections, and if the value is the default value of 0, the cookie is valid on both HTTP and HTTPS connections |
The COOKIE value of the browser can be read directly in PHP via the Super Global Array $_cookie[].
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd "><html xmlns="http://www.w3.org/1999/xhtml"><head> <meta http-equiv="Content-type" Content="text/html; charset=gb2312 " /> <title>PHP Language Basics</title></head><body><?phpDate_default_timezone_set ("PRC"); Header ("content-type:text/html; charset=gb2312 ");if(!isset($_cookie["Visittime"]) {Setcookie ("Visittime", Date ("y-m-d h:i:s"));Echo "This is the first time a cookie is saved"."<br>";}Else{Setcookie ("Visittime", Date ("y-m-d h:i:s"), time () + -);Echo "Last Access Time is:".$_cookie["Visittime"];Echo "<br>";}Echo "Visit time:". Date"y-m-d h:i:s");?></body></html>First Run Result:
This is the first time a cookie is saved
Visit Time: 16-07-16 08:26:25Second run Result:
Last access time: 16-07-16 08:26:25
Visit Time: 16-07-16 08:27:25
The above code, first through the isset () function to detect the existence of a cookie file, there is no Setcookie () function to create a cookie file, if there is a set cookie expiration time of 60 seconds.
Delete CookiesWhen a cookie is created, its cookie file is automatically deleted when the browser is closed without setting its expiration time. If you want to delete a cookie file before closing the browser, there are two ways: one is to use the Setcookie () function and the other is to delete the cookie manually in the browser. The following are described separately.
1. Use the Setcookie () function to delete cookies
deleting cookies and creating cookies is basically similar, and deleting cookies also uses the Setcookie () function. To delete a cookie simply set the second parameter in the Setcookie () function to a null value and set the expiration time of the 3rd parameter cookie to less than the current time of the system.
For example, set the expiration time of the cookie to the current time minus 1 seconds, as shown in the following code:
setcookie("name", "", time()-1);
In the preceding code, the time () function returns the current timestamp in seconds, and the expiration time is reduced by 1 seconds to get past the period, thereby removing the cookie.
2. Manually delete cookies in the browser
When using cookies, cookies automatically generate a text file that is stored in the Cookies Temp folder in Internet Explorer. Deleting a cookie file in a browser is a very convenient way.
If the cookie does not set the time, it means that its lifetime is the period of the browser session, and the cookie disappears automatically as soon as the Internet Explorer is closed. This cookie, known as a session cookie, is generally not saved on the hard disk, but in memory.
If the expiration time is set, then the browser will save the cookie to the hard disk, and the Internet Explorer will remain in effect until it expires.
Although cookies can be kept in the client browser for a long time, they are not immutable. Because the browser allows a maximum of 300 cookie files, and each cookie file supports a maximum capacity of 4KB, each domain name supports up to 20 cookies, and if the limit is reached, the browser automatically deletes the cookies randomly.
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