In web development, caching is an extremely important concept. It provides a way to solve performance problems and reduce the demand on server resources. PHP is a popular web language, and of course, it can also set up caching. This article will introduce how to set up caching in PHP pages.
1. What is cache
Cache is a very common term in the computer field. Its essence is to store frequently used data or programs close to users to improve access speed.
In web development, caching usually refers to storing a processed page or file in the memory of the web server to reduce the processing time for subsequent accesses.
2. Why use caching
In web development, page generation usually takes up a lot of time. When the number of visits increases, the load on the web server also increases. If each page request requires complete processing, the server's response time is likely to become very slow. Therefore, for those pages that are frequently requested, we can choose to cache these pages in memory, which can reduce the load on the Web server and improve the page response speed.
3. How to set up cache
In PHP, we can control browser cache and cache time by setting HTTP headers. The specific implementation method is as follows:
- Set the page expiration time
If we know that the content of a page will not change soon, we can set its expiration time to a very long time. Long time to reduce server response time.
// 设置缓存时间为1小时 $expires = 3600; header("Pragma: public"); header("Cache-Control: max-age=".$expires); header('Expires: ' . gmdate('D, d M Y H:i:s', time() + $expires) . ' GMT');
In the above example, we set the cache time through Cache-Control
. Here we set the cache time to 1 hour.
- Set the page modification time
If we know that a page may be modified at a certain time, then we can set a Last-Modified
tag to help the browser determine whether the page needs to be re-fetched. If the server modifies the page during future visits, the tag will be calculated at the same time.
// 读取文件修改时间并设置 Last-Modified 标记 $lastModifiedTime = filemtime($filePath); $etag = md5_file($filePath); header("Last-Modified: " . gmdate("D, d M Y H:i:s", $lastModifiedTime) . " GMT"); header("Etag: $etag");
In the above example, we used the filemtime()
function to get the last modification time of the file, and the md5_file()
function to get the Etag of the file value.
- Set page content change tag
In order to alleviate browser cache problems, we can update a version number or other similar tags when the page content changes. And let the browser re-read the page. In this way, even if the page content has not changed, the browser can still obtain the new page, thereby avoiding the problem of expired pages.
// 增加版本号 $version = 1; $url = "http://www.example.com/index.php?v=".$version; header("Location: ".$url);
In the above example, we add a version number to the accessed URL and redirect the browser to the URL, so as to inform the browser to re-obtain the page when the page is updated.
4. Summary
In Web development, caching is a common method to improve page response speed. In PHP, we can control the cache and cache time of the page by setting HTTP headers. However, caching can also cause problems if not set up properly, such as causing some pages to never be updated. Therefore, when using cache, we need to pay special attention to the setting of the cache time and the regular update of the content change mark of the page.
The above is the detailed content of How to set up cache for php pages (three methods). For more information, please follow other related articles on the PHP Chinese website!

The article compares ACID and BASE database models, detailing their characteristics and appropriate use cases. ACID prioritizes data integrity and consistency, suitable for financial and e-commerce applications, while BASE focuses on availability and

The article discusses securing PHP file uploads to prevent vulnerabilities like code injection. It focuses on file type validation, secure storage, and error handling to enhance application security.

Article discusses best practices for PHP input validation to enhance security, focusing on techniques like using built-in functions, whitelist approach, and server-side validation.

The article discusses strategies for implementing API rate limiting in PHP, including algorithms like Token Bucket and Leaky Bucket, and using libraries like symfony/rate-limiter. It also covers monitoring, dynamically adjusting rate limits, and hand

The article discusses the benefits of using password_hash and password_verify in PHP for securing passwords. The main argument is that these functions enhance password protection through automatic salt generation, strong hashing algorithms, and secur

The article discusses OWASP Top 10 vulnerabilities in PHP and mitigation strategies. Key issues include injection, broken authentication, and XSS, with recommended tools for monitoring and securing PHP applications.

The article discusses strategies to prevent XSS attacks in PHP, focusing on input sanitization, output encoding, and using security-enhancing libraries and frameworks.

The article discusses the use of interfaces and abstract classes in PHP, focusing on when to use each. Interfaces define a contract without implementation, suitable for unrelated classes and multiple inheritance. Abstract classes provide common funct


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Dreamweaver CS6
Visual web development tools
