群里也有些朋友对基础知识很不屑,总说有能力就可以了,基础知识考不出来什么.对于这样的观点,我一直不苟同.

Cache的作用不用说大家都知道咯,这些天也面试了一些人,发现很多人框架用多了,基础都忘记了,你问一些事情,他总是说框架解决了,而根本不明白是怎么回事,所以也提醒大家应该注意平时基础知识的积累,之后对一些问题才能游刃有余.

群里也有些朋友对基础知识很不屑,总说有能力就可以了,基础知识考不出来什么.对于这样的观点,我一直不苟同.
这个只是一点感概罢了. 下面看正题,介绍一个php的Cache类:

贴一下代码吧:下面也有下载地址，其实很简单，重要的是学习

<?php 
/** 
* o------------------------------------------------------------------------------o 
* | This package is licensed under the Phpguru license. A quick summary is | 
* | that for commercial use, there is a small one-time licensing fee to pay. For | 
* | registered charities and educational institutes there is a reduced license | 
* | fee available. You can read more at: | 
* | | 
* | http://www.phpguru.org/static/license.html | 
* o------------------------------------------------------------------------------o 
*/ 
/** 
* Caching Libraries for PHP5 
* 
* Handles data and output caching. Defaults to /dev/shm 
* (shared memory). All methods are static. 
* 
* Eg: (output caching) 
* 
* if (!OutputCache::Start('group', 'unique id', 600)) { 
* 
* // ... Output 
* 
* OutputCache::End(); 
* } 
* 
* Eg: (data caching) 
* 
* if (!$data = DataCache::Get('group', 'unique id')) { 
* 
* $data = time(); 
* 
* DataCache::Put('group', 'unique id', 10, $data); 
* } 
* 
* echo $data; 
*/ 
class Cache 
{ 
/** 
* Whether caching is enabled 
* @var bool 
*/ 
public static $enabled = true; 
/** 
* Place to store the cache files 
* @var string 
*/ 
protected static $store = '/dev/shm/'; 
/** 
* Prefix to use on cache files 
* @var string 
*/ 
protected static $prefix = 'cache_'; 
/** 
* Stores data 
* 
* @param string $group Group to store data under 
* @param string $id Unique ID of this data 
* @param int $ttl How long to cache for (in seconds) 
*/ 
protected static function write($group, $id, $ttl, $data) 
{ 
$filename = self::getFilename($group, $id); 
if ($fp = @fopen($filename, 'xb')) { 
if (flock($fp, LOCK_EX)) { 
fwrite($fp, $data); 
} 
fclose($fp); 
// Set filemtime 
touch($filename, time() + $ttl); 
} 
} 
/** 
* Reads data 
* 
* @param string $group Group to store data under 
* @param string $id Unique ID of this data 
*/ 
protected static function read($group, $id) 
{ 
$filename = self::getFilename($group, $id); 
return file_get_contents($filename); 
} 
/** 
* Determines if an entry is cached 
* 
* @param string $group Group to store data under 
* @param string $id Unique ID of this data 
*/ 
protected static function isCached($group, $id) 
{ 
$filename = self::getFilename($group, $id); 
if (self::$enabled && file_exists($filename) && filemtime($filename) > time()) { 
return true; 
} 
@unlink($filename); 
return false; 
} 
/** 
* Builds a filename/path from group, id and 
* store. 
* 
* @param string $group Group to store data under 
* @param string $id Unique ID of this data 
*/ 
protected static function getFilename($group, $id) 
{ 
$id = md5($id); 
return self::$store . self::$prefix . "{$group}_{$id}"; 
} 
/** 
* Sets the filename prefix to use 
* 
* @param string $prefix Filename Prefix to use 
*/ 
public static function setPrefix($prefix) 
{ 
self::$prefix = $prefix; 
} 
/** 
* Sets the store for cache files. Defaults to 
* /dev/shm. Must have trailing slash. 
* 
* @param string $store The dir to store the cache data in 
*/ 
public static function setStore($store) 
{ 
self::$store = $store; 
} 
} 
/** 
* Output Cache extension of base caching class 
*/ 
class OutputCache extends Cache 
{ 
/** 
* Group of currently being recorded data 
* @var string 
*/ 
private static $group; 
/** 
* ID of currently being recorded data 
* @var string 
*/ 
private static $id; 
/** 
* Ttl of currently being recorded data 
* @var int 
*/ 
private static $ttl; 
/** 
* Starts caching off. Returns true if cached, and dumps 
* the output. False if not cached and start output buffering. 
* 
* @param string $group Group to store data under 
* @param string $id Unique ID of this data 
* @param int $ttl How long to cache for (in seconds) 
* @return bool True if cached, false if not 
*/ 
public static function Start($group, $id, $ttl) 
{ 
if (self::isCached($group, $id)) { 
echo self::read($group, $id); 
return true; 
} else { 
ob_start(); 
self::$group = $group; 
self::$id = $id; 
self::$ttl = $ttl; 
return false; 
} 
} 
/** 
* Ends caching. Writes data to disk. 
*/ 
public static function End() 
{ 
$data = ob_get_contents(); 
ob_end_flush(); 
self::write(self::$group, self::$id, self::$ttl, $data); 
} 
} 
/** 
* Data cache extension of base caching class 
*/ 
class DataCache extends Cache 
{ 
/** 
* Retrieves data from the cache 
* 
* @param string $group Group this data belongs to 
* @param string $id Unique ID of the data 
* @return mixed Either the resulting data, or null 
*/ 
public static function Get($group, $id) 
{ 
if (self::isCached($group, $id)) { 
return unserialize(self::read($group, $id)); 
} 
return null; 
} 
/** 
* Stores data in the cache 
* 
* @param string $group Group this data belongs to 
* @param string $id Unique ID of the data 
* @param int $ttl How long to cache for (in seconds) 
* @param mixed $data The data to store 
*/ 
public static function Put($group, $id, $ttl, $data) 
{ 
self::write($group, $id, $ttl, serialize($data)); 
} 
} 
?>

使用方法：

$dir = !empty($_SERVER['argv'][1]) ? $_SERVER['argv'][1] : '.'; 
$dh = opendir($dir); 
while ($filename = readdir($dh)) { 
if ($filename == '.' OR $filename == '..') { 
continue; 
} 
if (filemtime($dir . DIRECTORY_SEPARATOR . $filename) < time()) { 
unlink($dir . DIRECTORY_SEPARATOR . $filename); 
} 
}

源码打包下载