php文件缓存类

<?php
/**
 * 文件缓存类
 */
class Infobird_Cache_File {
	// 缓存文件基础目录
	private $basePath;
	// 目录层次级别
	private $level;

	private static $instance;

	private function __construct($basePath, $level) {
		$this->setBasePath($basePath);
		$this->setLevel($level);
	}

	/**
	 * 设置缓存基础目录
	 * @param string $basePath
	 * @return void
	 * @throw Exception
	 */
	public function setBasePath($basePath) {
		$basePath = rtrim(str_replace('\\', '/', realpath($basePath)), '/') . '/';
		if (!file_exists($basePath)) {
			throw new Exception('Directory does not exist.');
		}
		
		$this->basePath = $basePath;
	}

	/**
	 * 设置目录层次级别
	 * @param int $level
	 * @return void 
	 * @throw Exception
	 */
	public function setLevel($level) {
		$level = (int)$level;
		if ($level <= 0 || $level > 5) {
			throw new Exception('Directory level too deep, level: 1-5.');
		}
		
		$this->level = $level;
	}

	/**
	 * 获取缓存路径
	 * @param string $key 
	 * @return string
	 * @throw Exception
	 */
	private function getCacheFilename($key) {
		$id = md5($key);

		$length = 2;
		$path = $this->basePath;
		$dir = $id;
		for ($pos = 0, $max = $this->level * $length; $pos < $max; $pos += $length) {
			$path .= substr($id, $pos, $length) . '/';
		}
			
		if (!file_exists($path)) {
			if (!mkdir($path, '0777', true)) {
				throw new Exception('Directory creation failed.' . $basePath);
			}
		}

		return $path . $key;
	}

	/**
	 * 设置缓存数据
	 * @param string $key
	 * @param mixed $value
	 * @return bool
	 *
	 */
	public function set($key, $value) {
		if (is_null($key) || !strlen($key)) {
			return false;
		}

		$data = null;
		if (is_array($value) || is_object($value)) {
			$data = serialize($value);
		}	

		$filename = $this->getCacheFilename($key);
		
		file_put_contents($filename, $data);
		
		return true;
	}

	/**
	 * 获取缓存数据
	 * @param string $key 
	 * @return mixed
	 */
	public function get($key) {
		if (is_null($key) || !strlen($key)) {
			return false;
		}

		$filename = $this->getCacheFilename($key);
		if (!file_exists($filename)) {
			return false;
		}

		$fileData = file_get_contents($filename);
		$data = @unserialize($fileData);

		return $data;
	}
	
	/**
	 * 删除缓存数据
	 * @param string $key
	 * @return bool
	 */
	public function del($key) {
		if (is_null($key) || !strlen($key)) {
			return false;
		}

		$filename = $this->getCacheFilename($key);
		if (file_exists($filename)) {
			@unlink($filename);
		}

		return true;
	}


	/**
	 * 获取实例
	 * @param string $basePath 缓存目录
	 * @param string $level 目录层次级别
	 * @return object
	 */
	public static function getInstance($basePath, $level = 2) {
		if (!self::$instance) {
			$basePath = $basePath ? $basePath : PROJECT_ROOT . '/cache';	
			self::$instance = new Infobird_Cache_File($basePath, $level);
		}

		return self::$instance;
	}

}