php caching tool class to implement web page caching, php tool class_PHP tutorial

php caching tool class implements web page caching, php tool class

php caching tool class implements web page caching

When PHP programs resist large traffic access, dynamic websites are often difficult to withstand, so a caching mechanism must be introduced. Generally, there are two types of caches

1. File caching

2. Data query result caching, using memory to implement cache

This example mainly uses file caching.

The main principle is to use the cache function to store the web page display results. If called again within the specified time, the cache file can be loaded.

Tool code:

// 文件缓存类
class Cache {
	/**
	 * $dir : 缓存文件存放目录
	 * $lifetime : 缓存文件有效期,单位为秒
	 * $cacheid : 缓存文件路径,包含文件名
	 * $ext : 缓存文件扩展名(可以不用),这里使用是为了查看文件方便
	 */
	private $dir;
	private $lifetime;
	private $cacheid;
	private $ext;
	/**
	 * 析构函数,检查缓存目录是否有效,默认赋值
	 */
	function __construct($dir = '', $lifetime = 1800) {
		if ($this->dir_isvalid ( $dir )) {
			$this->dir = $dir;
			$this->lifetime = $lifetime;
			$this->ext = '.Php';
			$this->cacheid = $this->getcacheid ();
		}
	}
	/**
	 * 检查缓存是否有效
	 */
	private function isvalid() {
		if (! file_exists ( $this->cacheid ))
			return false;
		if (! (@$mtime = filemtime ( $this->cacheid )))
			return false;
		if (mktime () - $mtime > $this->lifetime)
			return false;
		return true;
	}
	/**
	 * 写入缓存
	 * $mode == 0 , 以浏览器缓存的方式取得页面内容
	 * $mode == 1 , 以直接赋值(通过$content参数接收)的方式取得页面内容
	 * $mode == 2 , 以本地读取(fopen ile_get_contents)的方式取得页面内容(似乎这种方式没什么必要)
	 */
	public function write($mode = 0, $content = '') {
		switch ($mode) {
			case 0 :
				$content = ob_get_contents ();
				break;
			default :
				break;
		}
		ob_end_flush ();
		try {
			file_put_contents ( $this->cacheid, $content );
		} catch ( Exception $e ) {
			$this->error ( '写入缓存失败!请检查目录权限!' );
		}
	}
	/**
	 * 加载缓存
	 * exit() 载入缓存后终止原页面程序的执行,缓存无效则运行原页面程序生成缓存
	 * ob_start() 开启浏览器缓存用于在页面结尾处取得页面内容
	 */
	public function load() {
		if ($this->isvalid ()) {
			// 以下两种方式,哪种方式好?????
			require_once ($this->cacheid);
			echo "<!--缓存-->";
			// echo file_get_contents($this->cacheid);
			exit ();
		} else {
			ob_start ();
		}
	}
	/**
	 * 清除缓存
	 */
	public function clean() {
		try {
			unlink ( $this->cacheid );
		} catch ( Exception $e ) {
			$this->error ( '清除缓存文件失败!请检查目录权限!' );
		}
	}
	/**
	 * 取得缓存文件路径
	 */
	private function getcacheid() {
		return $this->dir . md5 ( $this->geturl () ) . $this->ext;
	}
	/**
	 * 检查目录是否存在或是否可创建
	 */
	private function dir_isvalid($dir) {
		if (is_dir ( $dir ))
			return true;
		try {
			mkdir ( $dir, 0777 );
		} catch ( Exception $e ) {
			$this->error ( '所设定缓存目录不存在并且创建失败!请检查目录权限!' );
			return false;
		}
		return true;
	}
	/**
	 * 取得当前页面完整url
	 */
	private function geturl() {
		$url = '';
		if (isset ( $_SERVER ['REQUEST_URI'] )) {
			$url = $_SERVER ['REQUEST_URI'];
		} else {
			$url = $_SERVER ['Php_SELF'];
			$url .= empty ( $_SERVER ['QUERY_STRING'] ) ? '' : '?' . $_SERVER ['QUERY_STRING'];
		}
		return $url;
	}
	/**
	 * 输出错误信息
	 */
	private function error($str) {
		echo '<div>$cachedir = './Cache/'; // 设定缓存目录
		$cache = new Cache ( $cachedir, 33 ); // 省略参数即采用缺省设置, $cache = new Cache($cachedir); 
		if (@$_GET ['cacheact'] != 'rewrite' || @$_GET ['clearCache'] == 'ok') // 此处为一技巧,通过xx.Php?cacheact=rewrite更新缓存,以此类推,还可以设定一些其它操作
			$cache->load (); // 装载缓存,缓存有效则不执行以下页面代码
		// 页面代码开始

　

The

part is placed behind the cached logic code:

// 页面代码结束
		$cache->write (); // 首次运行或缓存过期,生成缓存

　

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