Cookie technology in PHP and its common application examples

In Web development, Cookie technology is a very common technology. It is a way of passing data between a web server and a browser, and is often used to store temporary data or user preferences. In this article, we will introduce Cookie technology in PHP and its common application examples.

1. What is Cookie technology

Cookie technology is a mechanism for recording client status in the HTTP protocol.

When the browser sends a request to the server, the server's response header can contain the Set-Cookie field. The value of this field is a text string, which usually contains a name (key) and a value. After the browser receives this header information, it will save the name and value locally. When the client sends a request to the server again, the cookie information will be included in the request header, so that the server can determine the client's identity and previous status.

2. Cookie technology in PHP

In PHP, use the setcookie() function to set cookies. The syntax of this function is as follows:

bool setcookie ( string $name [, string $value [, int $expire

         [, string $path [, string $domain [, bool $secure
         [, bool $httponly ]]]]]] )

where $name is the Cookie name, $value is the Cookie value, $ expire is the expiration time (expressed as a Unix timestamp). $path and $domain are used to limit the path and domain name under which the cookie is valid. When $secure is true, it means that only HTTPS connections are allowed to use the cookie. When $httponly is true, it means Access is only allowed through the HTTP protocol, and access through JavaScript scripts is prohibited.

In addition to using the setcookie() function, PHP also provides some other Cookie-related functions, such as $_COOKIE for accessing stored cookies. The setrawcookie() function is used to set cookies that do not require URL encoding, etc.

3. Application examples of Cookie technology

1. User login status management

In the Web In applications, users usually need to be authenticated to determine the user's identity. Cookies can be used to manage the user's login status.

When the user logs in, the server can set a name named "user_id" Cookie and set its value to the user's ID. In this way, when the user continues to browse the website, the server can use this cookie to identify whether the user is logged in and provide corresponding services.

2. Products Shopping cart

The shopping cart is an important part of an e-commerce website. The shopping cart is usually saved on the server side, but in order to improve the user experience, the shopping cart information is usually saved in cookies.

When shopping online, users can add products to the shopping cart by clicking the "Add to Cart" button. The server saves the information about the products selected by the user in Cookie, and the user can delete the products later on the shopping cart page. Modification and other operations.

3. Website preferences

Some websites need to provide users with some preferences, such as background color, font size, etc. These preferences are usually saved through cookies .

When the user makes preference changes, the server saves these settings to Cookie, so that the user can see their previous preferences when they visit the website again.

4. Summary

In this article, we introduce Cookie technology in PHP and its common application examples. In actual projects, Cookie technology can help us realize many functions, such as user status management, shopping cart, etc. At the same time, Using Cookie technology also requires attention to some security issues, such as Cookie session hijacking, Cookie injection attacks, etc. Therefore, we need to update security measures in a timely manner during the development process.

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