文件缓存

Cache：

<?php
class Cache
{
    private static $_instance = null;
    
    protected $_options = array();
    
    protected function __construct()
    {
    }
    
    /**
     * 得到本类实例
     * array(
     *            'cache_dir' => '',
     *            'file_name_prefix' => '',
     *        )
     * @return Ambiguous
     */
    public static function getInstance($config)
    {
        if (self::$_instance === null) {
            self::$_instance           = new self();
            self::$_instance->_options = $config;
        }
        return self::$_instance;
    }
    
    /**
     * 得到缓存信息
     * 
     * @param string $id
     * @return boolean|array
     */
    public static function get($id)
    {
        $instance = self::$_instance;
        
        //缓存文件不存在
        if (!$instance->has($id)) {
            return false;
        }
        
        $file = $instance->_file($id);
        
        $data = $instance->_fileGetContents($file);
        
        if ($data['expire'] == 0 || time() < $data['expire']) {
            return $data['contents'];
        } else {
            @unlink($file); //过期删除缓存
        }
        return false;
    }
    
    /**
     * 设置一个缓存
     * 
     * @param string $id   缓存id
     * @param array  $data 缓存内容
     * @param int    $cacheLife 缓存生命 默认为0无限生命
     */
    public static function set($id, $data, $cacheLife = 0)
    {
        $instance = self::$_instance;
        
        $time              = time();
        $cache             = array();
        $cache['contents'] = $data;
        $cache['expire']   = $cacheLife === 0 ? 0 : $time + $cacheLife;
        $cache['mtime']    = $time;
        
        $file = $instance->_file($id);
        
        return $instance->_filePutContents($file, $cache);
    }
    
    /**
     * 清除一条缓存
     * 
     * @param string cache id    
     * @return void
     */
    public static function delete($id)
    {
        $instance = self::$_instance;
        
        if (!$instance->has($id)) {
            return false;
        }
        $file = $instance->_file($id);
        //删除该缓存
        return unlink($file);
    }
    
    /**
     * 判断缓存是否存在
     * 
     * @param string $id cache_id
     * @return boolean true 缓存存在 false 缓存不存在
     */
    public static function has($id)
    {
        $instance = self::$_instance;
        $file     = $instance->_file($id);
        
        if (!is_file($file)) {
            return false;
        }
        return true;
    }
    
    /**
     * 通过缓存id得到缓存信息路径
     * @param string $id
     * @return string 缓存文件路径
     */
    protected function _file($id)
    {
        $instance = self::$_instance;
        $fileNmae = $instance->_idToFileName($id);
        return $instance->_options['cache_dir'] . $fileNmae;
    }
    
    /**
     * 通过id得到缓存信息存储文件名
     * 
     * @param  $id
     * @return string 缓存文件名
     */
    protected function _idToFileName($id)
    {
        $instance = self::$_instance;
        $prefix   = $instance->_options['file_name_prefix'];
        return sha1($prefix . $id) . '.dat';
    }
    
    /**
     * 把数据写入文件
     * 
     * @param string $file 文件名称
     * @param array  $contents 数据内容
     * @return bool 
     */
    protected function _filePutContents($file, $contents)
    {
        $contents = serialize($contents);
        
        $result = false;
        $f      = @fopen($file, 'w');
        if ($f) {
            @flock($f, LOCK_EX);
            fseek($f, 0);
            ftruncate($f, 0);
            $tmp = @fwrite($f, $contents);
            if (!($tmp === false)) {
                $result = true;
            }
            @flock($f, LOCK_UN);
            @fclose($f);
        }
        @chmod($file, 0777);
        return $result;
    }
    
    /**
     * 从文件得到数据
     * 
     * @param  sring $file
     * @return boolean|array
     */
    protected function _fileGetContents($file)
    {
        if (!is_file($file)) {
            return false;
        }
        
        $f = @fopen($file, 'r');
        @$data = fread($f, filesize($file));
        @fclose($f);
        
        return unserialize($data);
    }
    
    /**
     * 设置缓存路径
     * 
     * @param string $path
     * @return self
     */
    public static function setCacheDir($path)
    {
        $instance = self::$_instance;
        if (!is_dir($path)) {
            exit('file_cache: ' . $path . ' 不是一个有效路径 ');
        }
        if (!is_writable($path)) {
            exit('file_cache: 路径 "' . $path . '" 不可写');
        }
        
        $path                            = rtrim($path, '/') . '/';
        $instance->_options['cache_dir'] = $path;
        
        return $instance;
    }
    
    /**
     * 设置缓存文件前缀
     * 
     * @param srting $prefix
     * @return self
     */
    public static function setCachePrefix($prefix)
    {
        $instance                               = self::$_instance;
        $instance->_options['file_name_prefix'] = $prefix;
        return $instance;
    }
    
    /**
     * 删除所有缓存
     * @return boolean
     */
    public static function flush()
    {
        $instance = self::$_instance;
        $glob     = @glob($instance->_options['cache_dir'] . '*');
        
        if (empty($glob)) {
            return false;
        }
        
        foreach ($glob as $v) {
            @unlink($v);
        }
        
        return true;
    }
}

调用：

<?php
require 'FileCache.php';

$cachPath = dirname(__FILE__) . '/cache/';

$config = array(
    'cache_dir' => $cachPath,
    'file_name_prefix' => 'cache',
);

$cache = Cache::getInstance($config);

$cache->set('sex', 'women', 5);
$cache->set('name', 'jack');

$cache->set('age', 20, 3);

echo $cache->get('name');
echo $cache->get('sex');