PHP's caching mechanism realizes page static code sharing

This article mainly brings you a method to achieve page staticization using PHP's ob cache mechanism. The editor thinks it is quite good, so I will share it with you now and give it as a reference for everyone. Let’s follow the editor to take a look, I hope it can help everyone.

First introduce some common functions commonly used in ob cache in php

ob_start(): Turn on the cache mechanism

ob_get_contents(): Get the ob cache The content

ob_clean() clears the content in the ob cache, but does not close the cache

ob_end_clean() clears the content in the ob cache, and closes the cache

ob_flush clears the cache , output the content, but do not close the cache

ob_end_flush Clear the cache, output the content, and close the cache

flush forces the content in the output cache to be refreshed

According to the provisions of the http protocol, The response content cannot be output before the response header. Therefore, if there is content output before the header() function, an error will occur. However, after using ob_start(), the response content will be placed in the ob cache first, and no message will be sent again. The header is sent before it is sent, which solves the problem of header() error!

Let’s talk about how to use the ob cache mechanism that comes with PHP to achieve page staticization. The sample code is as follows

<?php   
    $id=$_REQUEST[&#39;id&#39;];
    
    //判断缓存文件是否存在，如果存在，直接输出
    if(file_exists(&#39;content&#39;.$id.&#39;.html&#39;)){
      echo file_get_contents(&#39;content&#39;.$id.&#39;.html&#39;);
      return;
    }
    
    //开启缓存机制
    ob_start();
    
    //到数据库中查询所需要的内容
    $conn=mysql_connect("localhost","root","root");
    mysql_select(&#39;db&#39;);
    mysql_query(&#39;set names utf8&#39;);
    
    $sql="select content from table_name where id=$id";
    $res=mysql_query($sql);
    $row=mysql_fetch_assoc($res);
    $content=$row[0];
    
    mysql_free_result($res);
    mysql_close($conn);
    echo $content;
    //将输出的内容保存到文件中，形成静态页面，在下次访问的时候，直接读取输出
    file_put_contents(&#39;content&#39;.$id.&#39;.html&#39;,ob_get_contents());


?>

As shown in the above code:

Query us to The content is directly saved to the html file. If the file exists, output it. If it does not exist, access the database and execute the corresponding query process.

If you want to set the expiration time of the file, you can add it in the if statement. A judgment condition used to judge whether the cache file has expired, time () - the set expiration time.

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