Summary of PHP page caching methods
The main use of the PHP page cache is the OB series functions, such as Ob_start (), Ob_end_flush (), ob_get_contents (), but more advanced caches do not use these functions, this article will give an example to illustrate.
Let's take a look at the usual OB series functions for caching:
Ob_start (): The start of the page cache flag, the function of the content until Ob_end_flush () or Ob_end_clean () are saved in the page cache;
Ob_get_contents (): Used to get the content in the page cache, get to the future, we can think how to deal with these content is OK, filter field, match content, can ~ ~ ~
Ob_end_flush (): Indicates the end of the page cache, and by my verification, the cached content will be output to the current page, that is, the cached content can be displayed.
With these three PHP functions, you can achieve a powerful function, if the database query volume is large, you can use the cache to solve the problem.
Here is the coding section.
1. Initialization function, usually set the page cache path, cache file naming format, can be customized according to personal preferences, the identification ID used here is an encrypted $_server[request_uri] parameter, this function finally has an if judgment, if not over the cache period, the cache file is loaded, Otherwise load the source file with the following code:
The code is as follows:
function Page_Init ()
{
$url = $_server[' request_uri '];//child URL, this parameter is generally unique
$pageid = MD5 ($url);
$dir = Str_replace ('/', ' _ ', substr ($_server[' script_name '],1,-4));
Directory naming methods, such as Exp_index
if (!file_exists ($pd = Page_path $dir. '/')) @mkdir ($pd, 0777) or Die ("$PD Directory Creation failed");
such as cache/page/exp_index/
Define (' Page_file ', $pd. $pageid. HTML ');
such as cache/page/exp_index/cc8ef22b405566745ed21305dd248f0e.html
$contents = file_get_contents (page_file);//read out
if ($contents && substr ($contents, up to ten) > Time ())//corresponds to the custom header added to the Page_cache () function
{
Echo substr ($contents, 27);
Exit (0);
}
return true;
}
2. Page cache function, where a technique is used to add a header to the contents of the cache file-expiration time, so each time only need to compare the expiration time in the head and the current time, in the Page_Init () function, you can determine whether the cache expires, the code is as follows:
Copy the code code as follows:
function Page_cache ($ttl = 0)
{
$ttl = $ttl? $ttl: page_ttl;//cache time, default 3600s
$contents = Ob_get_contents ();//get content from the cache
$contents = " n ". $contents;
Plus Custom headers: Expiry time = build time + cache time
File_put_contents (Page_file, $contents);//write to the cache file
Ob_end_flush ();//Release cache
}
3. Function use, note that the two functions have a sequential order of execution, but also do not forget Ob_start (), the code is as follows:
The code is as follows:
Page_Init ();//Page Cache initialization
Ob_start ();//Open cache
...//code snippet
Page_cache (60);//usually the last line
?>
Example 2, below is an example to illustrate the PHP page caching technology, the code is as follows:
The code is as follows:
$_time = 10;
$dir = "D:\php\";
function Cache_start ($_time, $dir)
{
$cachefile = $dir. '/'. SHA1 ($_server[' Request_uri '). HTML ';
$cachetime = $_time;
Ob_start ();
if (file_exists ($cachefile) && (Time ()-filemtime ($cachefile) < $cachetime))
{
Include ($cachefile);
Ob_end_flush ();
Exit
}
}
function Cache_end ($dir)
{
$cachefile = $dir. '/'. SHA1 ($_server[' Request_uri '). HTML ';
$fp = fopen ($cachefile, ' w ');
Fwrite ($FP, ob_get_contents ());
Fclose ($FP);
Ob_end_flush ();
}
Cache_start ($_time, $dir);
The following is the output, placed between Cache_start and Cache_end two methods
for ($i =0; $i <5; $i + +)
{
echo $i;
Sleep (1);
}
Cache_end ($dir);
?>
example, using the generated file for caching, the code is as follows:
The code is as follows:
Ob_start ();
/**
* @author He Nihui
* @copyright 2009-3-13
* @param string $cache _folder Slow folder
* @param int $cache _create_time File cache time
* @example $cache =new esj_cache ('./_cache ', 100)
* @example $cache->read_cache () read cache and output
* @example $cache->creatre_cache () to create a cache file (placed in the end of the file)
* @example $cache->list_file () returns a list of all cached files
* @example $cache->del_file () Delete all cache files
*/
Class esj_cache{
Private $cache _folder=null;//cacher Folder
Private $wroot _dir=null;//Site Directory
Private $cacher setup time for _create_time=null;//cacher files
Public function __construct ($cache _foldername, $cacher _time=100)
{
Ob_start ();
$this->wroot_dir=$_server[' Document_root '];
$this->cache_folder= $cache _foldername;
$this->cacher_create_time= $cacher _time;
}
Public Function Read_cache ()
{
try {
if (Self::create_folder ($this->cache_folder))
{
Self::get_cache ();//output cache file information
}else
{
echo "Cache folder creation failed!";
return false;
}
}catch (Exception $e) {
Echo $e;
return false;
}
}
Test whether the cache folder exists
Private Function Exist_folder ($foler)
{
if (file_exists ($this->wroot_dir. /". $foler)) {
return true;
}else {
return false;
}
}
Create a new Folder
Private Function Create_folder ($foler)
{
if (!self::exist_folder ($foler))
{
try{
mkdir ($this->wroot_dir. " /". $foler, 0777);
chmod ($this->wroot_dir. " /". $foler, 0777);
return true;
}catch (Exception $e)
{
Self::get_cache ();//Output cache
return false;
}
return false;
}
Else
{
return true;
}
}
Reading cache files
Private Function Get_cache ()
{
$file _name=self::get_filename ();
if (file_exists ($file _name) && ((Filemtime ($file _name) + $this->cacher_create_time) > Time ()))
{
$content =file_get_contents ($file _name);
if ($content)
{
Echo $content;
Ob_end_flush ();
Exit
}else
{
echo "file read failed";
Exit
}
}
}
Returns the name of the file
Private Function Get_filename ()
{
$filename = $file _name= $this->wroot_dir. '/'. $this->cache_folder. ' /'. MD5 ($_server[' query_string '). ". HTML ";
return $filename;
}
Create a cache file
Public Function Create_cache ()
{
$filename =self::get_filename ();
if ($filename! = "")
{
try{
File_put_contents ($filename, ob_get_contents ());
return true;
}catch (Exception $e)
{
echo "Write Cache failed:". $e;
Exit ();
}
return true;
}
}
Get all the files in the cache
Public Function List_file ()
{
$path = $this->cache_folder;
if ($handle = Opendir ($path)) {
while (false!== ($file = Readdir ($handle))) {
if ($file! = "." && $file! = "...") {
$path 1= $path. " /". $file;
if (file_exists ($path 1))
{
$result []= $file;
}
}
}
Closedir ($handle);
}
return $result;
}
Delete all files in the cache
Public Function Del_file ()
{
$path = $this->cache_folder;
if ($handle = Opendir ($path)) {
while (false!== ($file = Readdir ($handle))) {
if ($file! = "." && $file! = "...") {
$path 1= $path. " /". $file;
if (file_exists ($path 1))
{
Unlink ($path 1);
}
}
}
Closedir ($handle);
}
return true;
}
}
?>
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