Source Code Analysis of the Cache class

The source code of the Cache class analyzes the source code of a Cache class. For more information about how to learn the Cache, see? /* Constants to be defined in advance: _ CachePath _ template cache path _ CacheEnable _ whether the automatic Cache mechanism is enabled, undefined or empty, indicates the automatic Cache mechanism _ ReCacheTime _ automatic cache re-interval, in seconds, undefined or empty Source Code Analysis of the Cache class

For source code analysis of a Cache class, refer
/*
Constants that need to be defined in advance:
_ CachePath _ template cache path
_ CacheEnable _ whether the automatic Cache mechanism is enabled. if it is undefined or empty, the automatic Cache mechanism is disabled.
_ ReCacheTime _ automatic cache re-caching interval, in seconds. if it is undefined or empty, automatic cache re-caching is disabled.
_ ActionVar _ GET variable of Action

Sample:
$ Cache = new cache ();
If ($ cache-> check ()){
$ Template = $ cache-> read ();
} Else {
......
$ Cache-> write ($ template );
}
Eval ('echo $ template ;');
*/

Class cache {

Var $ cachefile;
Var $ cachefilevar;

Function cache (){
// Generate the name of the Cache group for the current page $ this-> cachefilevar and the name $ this-> cachefile
// Different dynamic page parameters correspond to different Cache files, but all the Cache files on each dynamic page have the same file name, but the extensions are different.
$ S = array (".", "/"); $ r = array ("_","");
$ This-> cachefilevar = str_replace ($ s, $ r, $ _ SERVER ["SCRIPT_NAME"]). "_". $ _ GET [_ ActionVar _];
$ This-> cachefile = $ this-> cachefilevar. ".". md5 ($ _ SERVER ["REQUEST_URI"]);
}

// Delete the cache of the current page/module
Function delete (){
// Delete the cache of the current page
$ D = dir (_ CachePath _);
$ Strlen = strlen ($ this-> cachefilevar );
// Return all Cache file groups on the current page
While (false! ==( $ Entry = $ d-> read ())){
If (substr ($ entry, 0, $ strlen) = $ this-> cachefilevar ){
If (! Unlink (_ CachePath _. "/". $ entry) {echo "the Cache directory cannot be written"; exit ;}
}
}
}

// Determine whether or not the Cache has been cached and whether the Cache is required
Function check (){
// If the cache update interval _ ReCacheTime _ is set _
If (_ ReCacheTime _ + 0> 0 ){
// Return the last update time of the current page Cache
$ Var = @ file (_ CachePath _. "/". $ this-> cachefilevar); $ var = $ var [0];
// Delete the Cache file if the update time exceeds the update interval
If (time ()-$ var> _ ReCacheTime _){
$ This-> delete (); $ ischage = true;
}
}
// Return the Cache of the current page
$ File = _ CachePath _. "/". $ this-> cachefile;
// Determine whether the current page Cache exists and whether the Cache function is enabled
Return (file_exists ($ file) and _ CacheEnable _ and! $ Ischange );
}

// Read Cache
Function read (){
// Return the Cache of the current page
$ File = _ CachePath _. "/". $ this-> cachefile;
// Read the content of the Cache file
If (_ CacheEnable _) return file_get_contents ($ file );
Else return false;
}

// Generate Cache
Function write ($ output ){
// Return the Cache of the current page
$ File = _ CachePath _. "/". $ this-> cachefile;
// If the Cache function is enabled
If (_ CacheEnable _){
// Write the output content to the Cache file
$ Fp = @ fopen ($ file, 'w ');
If (! @ Fwrite ($ fp, $ output) {echo "template Cache write failed"; exit ;}
@ Fclose ($ fp );
// If the cache update interval _ ReCacheTime _ is set _
If (_ ReCacheTime _ + 0> 0 ){
// Update the last update time of the current page Cache
$ File = _ CachePath _. "/". $ this-> cachefilevar;
$ Fp = @ fopen ($ file, 'w ');
If (! @ Fwrite ($ fp, time () {echo "the Cache directory cannot be written"; exit ;}
@ Fclose ($ fp );
}
}
}

}