How to implement page static caching code in php

PHP is a popular scripting language used to create dynamic web pages and process form data. In many cases, PHP code needs to perform a certain amount of calculations and data processing to generate the dynamic content of a web page. This kind of dynamically generated web page needs to recalculate the data in the page when the user accesses the same page, which causes the web page loading time to become longer and affects the user experience. To solve this problem, page static caching technology can be used.

Page static caching refers to caching dynamically generated web pages so that the cached content can be directly returned in subsequent visits without having to perform calculations and data processing operations. This can greatly improve the response speed of web pages and reduce server load and network bandwidth usage. There are many ways to implement page static caching in PHP. The following is one of the simple implementation methods.

Step one: Determine whether the cache exists

In PHP code, you can judge whether a file needs to be regenerated by the modification time of the file. If the file already exists and the modification time is within a certain time range, the cached content can be read directly, otherwise the cache needs to be regenerated. The following is the code to determine whether the cache exists:

$cache_file = 'cache.html'; // 缓存文件名
$expiry = time() - 60 * 60; // 缓存过期时间，这里设置为1小时前
if (file_exists($cache_file) && filemtime($cache_file) > $expiry) {
    // 直接读取缓存文件内容
    readfile($cache_file);
    exit();
}

The above code first defines the name of the cache file as cache.html, and then sets the cache expiration time to 1 hour ago. Next, use the file_exists() function to check whether the cache file exists. If it exists, obtain the modification time of the file through the filemtime() function and compare whether the time is within the specified expiration time. If the conditions are met, the contents of the cache file are directly read and output to the browser and the program execution ends.

Step 2: Generate cache content

If the cache does not exist or has expired, you need to generate new cache content. The process of generating a cache can be to call other functions or perform database queries, or to save the HTML code of dynamic web pages to a file. The following is an example of generating cached content:

// 生成新的缓存内容
ob_start(); // 开始输出缓冲
// 在这里写你的动态内容生成代码
echo '<h1>Welcome to my website!</h1>';
// 结束输出缓冲，获取缓冲区的内容
$content = ob_get_clean();
// 把缓冲区的内容保存到缓存文件中
file_put_contents($cache_file, $content);
// 输出缓存内容到浏览器并结束程序执行
echo $content;
exit();

The above code uses PHP's output buffering functions ob_start() and ob_get_clean(). After calling the ob_start() function, all output content will be cached in memory. The cache will not be cleared until the ob_get_clean() function is called to obtain the cached data. In this way, we can write the HTML code of the dynamic web page between ob_start() and ob_get_clean(), save it to the $content variable, and then save the content in the $content variable as a cache file. Finally, the contents of the $content variable are output to the browser and the program execution ends. The user will see the generated cached HTML code.

Step Three: Complete Code

The above is an example of simply implementing page static caching. The following is the complete code:

// 缓存文件名
$cache_file = 'cache.html';
// 缓存过期时间，这里设置为1小时前
$expiry = time() - 60 * 60;
// 判断缓存是否存在
if (file_exists($cache_file) && filemtime($cache_file) > $expiry) {
    // 直接读取缓存文件内容
    readfile($cache_file);
    exit();
} else {
    // 开始输出缓冲
    ob_start();
    // 在这里写你的动态内容生成代码
    echo '<h1>Welcome to my website!</h1>';
    // 结束输出缓冲，获取缓冲区的内容
    $content = ob_get_clean();
    // 把缓冲区的内容保存到缓存文件中
    file_put_contents($cache_file, $content);
    // 输出缓存内容到浏览器并结束程序执行
    echo $content;
    exit();
}

In the above code, it is judged through the if statement Whether the cache file exists. If it exists and the modification time is before the expiration time, the contents of the cache file are directly read and output to the browser. Otherwise, call the ob_start() function to start the output buffer, write the content generation code of the dynamic web page, obtain the cache content through the ob_get_clean() function and save it to the $content variable, and then call the file_put_contents() function to save the content in the $content variable. into the cache file. Finally, the content in the $content variable is output to the browser and the program execution ends.

Summary

Page static caching technology can significantly improve the response speed and user experience of web pages, and reduce the load of the server and the use of network bandwidth. There are many ways to implement page static caching in PHP. We can reduce the calculation and processing of dynamic pages by determining whether cache files exist and have not expired, and improve efficiency by generating static HTML file caches.

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