Analyze how PHP uses the ob cache mechanism to implement page static solutions

Pre-converting the PHP execution page into HTML is one of the so-called PHP static methods.

Other methods include template replacement, opcache and other methods.

The role of staticization:

Improve the response speed of the website and reduce the load of the server;
Used for search engine SEO;
Use PHP output buffer to write directly into html, timing Scanning the website regularly in the background is a relatively easy way to achieve static web pages.

Before staticization:

for($i=0;$i

echo "bull
";

}

?>

Static:

ob_start();

for($i=0;$i

echo "bull< ;br>";

}

$str = ob_get_contents();

ob_end_clean();

$fp = fopen("test.html ","w");

fwrite($fp,$str);

fclose($fp);

echo "

success write div>";

?>

This code will pre-form a test.html. To put it bluntly, it is actually using space in exchange for Time, like news websites, the published content will basically not change after it is written, so it is more suitable to statically convert it into HTML.

When users visit, they just need to direct to this html page.

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

ob_start(): open Caching mechanism

ob_get_contents(): Get the contents of the ob cache

ob_clean() Clear the contents of the ob cache, but do not close the cache

ob_end_clean() Clear the ob cache content in the cache, and close the cache

ob_flush Clear 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 output to be refreshed Content in the cache

According to the provisions of the http protocol, the response content cannot be output before the response header. Therefore, if there is content output in front of the header() function, an error will occur, but after using ob_start() The response content will be placed in the ob cache first and will not be sent before the message header is sent. This solves the problem of header() error reporting!

Let’s talk about how to use PHP’s own ob cache mechanism to achieve page staticization

Code Schoolphp

 1 <?php  2     3     $id=$_REQUEST[&#39;id&#39;]; 4       5     //判断缓存文件是否存在，如果存在，直接输出 6     if(file_exists(&#39;content&#39;.$id.&#39;.html&#39;)){ 7       echo file_get_contents(&#39;content&#39;.$id.&#39;.html&#39;); 8       return; 9     }10      11     //开启缓存机制12     ob_start();13      14     //到数据库中查询所需要的内容15     $conn=mysql_connect("localhost","root","root");16     mysql_select(&#39;db&#39;);17     mysql_query(&#39;set names utf8&#39;);18      19     $sql="select content from table_name where id=$id";20     $res=mysql_query($sql);21     $row=mysql_fetch_assoc($res);22     $content=$row[0];23      24     mysql_free_result($res);25     mysql_close($conn);26     echo $content;27     //将输出的内容保存到文件中，形成静态页面，在下次访问的时候，直接读取输出28     file_put_contents(&#39;content&#39;.$id.&#39;.html&#39;,ob_get_contents());29  30  31 ?>

As shown in the above code:

Save the content we query directly into the html file. If the file exists, it will be output. If it does not exist, Then access the database and execute the corresponding query process

If you want to set the expiration time of the file, you can add a judgment condition in the if statement to determine whether the cached file has expired, time()-the set expiration time

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