In the PHP page cache is mainly used in the OB series functions, such as Ob_start (), Ob_end_flush (), ob_get_contents (), but the more advanced cache is not using these functions, the last implementation of this article is mentioned, we can refer to.
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 I verified that the cached content will be output to the current page, that is, the cache content can be displayed.
With these three PHP functions, you can implement powerful functions. If the database query volume is large, you can use the cache to solve this problem.
Here is the coding section.
1. Initialization function, usually set the page cache path, cache file naming format, etc., can be customized according to personal preferences. The identification ID used here is an encrypted $_server[request_uri] parameter. Finally, there is an if judgment in this function: if the cache period is not over, the cached file is loaded, otherwise the source file is loaded.
| The code is as follows |
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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, here is a trick: Add a header to the contents of the cache file-the expiration time, so each time only need to compare the expiration time in the head and the current time (in the Page_Init () function) can determine whether the cache expires.
| The code is as follows |
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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, $contents);//write to the cache file
Ob_end_flush ();//Release cache
}
|
3. Function Use, note that these two functions have the order of execution, but also forget the Ob_start ()
| The code is as follows |
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Page_Init ();//Page Cache initialization
Ob_start ();//Open cache
...//code snippet
Page_cache (60);//usually the last line
?>
|
Example 2
Here is an example to illustrate the PHP page caching technique:
| The code is as follows |
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$_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);
?> |
Cases
Cache with Makefile
| The code is as follows |
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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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