文件缓存了解下

超、凢脫俗 2022-04-06 01:50 139阅读 0赞

文件缓存就是指把缓存数据存储到文件系统也就是硬盘中，大家都知道与内存相比，硬盘是属于速度比较慢的存储设备，为什么我们要使用这个呢？？？

原因很简单，磁盘容量大，可以存放足够多的数据，现在常规的硬盘已经进入到了TB级别，而内存还处于GB级别，并且呢，磁盘的价格远远低于内存，它还比内存更加的稳定和可靠，最起码断电后数据不会丢失，存储也是比较简单，还有就是固态硬盘的出现，使得硬盘的读写速度得到了极大的提升，最后就是扩展方面了，我们可以使用磁盘阵列、分布式处理等进行大规模的存储和管理，相比较来说，貌似确实是硬盘性价比更高些。

文件缓存机制的逻辑很清晰，模板的作用之一就是把动态的PHP动态代码编译成静态的HTML文件，当下次读取的时候不会再经过编译，我们来看一个简单的模板引擎进行文件缓存的代码实例，首先是模板类：

//Template.php
    class Template{
        private $arrayConfig = array(
            'suffix' => '.m', //模板文件的后缀
            'template_dir' => 'template/', //模板所在的文件夹
            'compile_dir' => 'cache/', //模板编译后存放的目录
            'html' => false, //是否需要编译为静态的HTML文件
            'suffix_cache' => '.html', //编译文件的后缀
            'cache_time' => 3600, //多长时间自动更新，单位，秒
            'php' => true,
            'cache_control' => 'control.dat',
            'debug' => false
        );
        private $value = array();
        private $compile_tool;
        public $file; //模板名称
        public $debug = array();
        private $control_data = array();
        static private $instance = null;
        public function __construct($arrayConfig = array())
        {
            $this->debug['begin'] = microtime(true);
            $this->arrayConfig = $arrayConfig + $this->arrayConfig;
            $this->get_path();
            if(!is_dir($this->arrayConfig['template_dir'])){
                exit('template');
            }
            if(!is_dir($this->arrayConfig['compile_dir'])){
                exit('compile');
            }
            include ('CompileClass.php');
        }
    
        public function get_path()
        {
            $this->arrayConfig['template_dir'] = strtr(realpath($this->arrayConfig['template_dir']),'\\','/')."/";
            $this->arrayConfig['compile_dir'] = strtr(realpath($this->arrayConfig['compile_dir']),'\\','/')."/";
        }
    
        public static function get_instance()
        {
            if(is_null(self::$instance)){
                self::$instance = new Template();
            }
    
            return self::$instance;
        }
    
        public function set_config($key,$value=null)
        {
            if(is_array($key)){
                $this->arrayConfig = $key + $this->arrayConfig;
            }else{
                $this->arrayConfig[$key] = $value;
            }
        }
    
        public function get_config($key=null)
        {
            if($key){
                return $this->arrayConfig[$key];
            }else{
                return $this->arrayConfig;
            }
        }
    
        public function assign($key,$value)
        {
            $this->value[$key] = $value;
        }
    
        public function assign_arr($array)
        {
            if(is_array($array)){
                foreach ($array as $item=>$value) {
                    $this->value[$item] = $value;
                }
            }
        }
    
        public function path()
        {
            return $this->arrayConfig['template_dir'].$this->file.$this->arrayConfig['suffix'];
        }
    
        public function need_cache()
        {
            return $this->arrayConfig['html'];
        }
    
        public function re_cache($file)
        {
            $flag = false;
            $cache_file = $this->arrayConfig['compile_dir'].md5($file).'.html';
            if($this->arrayConfig['html'] == true){
                $time_flag = (time()-@filemtime($cache_file)) < $this->arrayConfig['cache_time'] ? true : false;
                if(is_file($cache_file) && filesize($cache_file) > 1 && $time_flag){
                    $flag = true;
                }else{
                    $flag = false;
                }
            }
    
            return $flag;
        }
    
        public function show($file)
        {
            $this->file = $file;
            if(!is_file($this->path())){
                exit('there is nothing to make');
            }
    
            $compile_file = $this->arrayConfig['compile_dir'].md5($file).".php";
            $cache_file = $this->arrayConfig['compile_dir'].md5($file).".html";
    
            if($this->re_cache($file) === false){
                $this->debug['cached'] = 'false';
                $this->compile_tool = new CompileClass($this->path(),$compile_file,$this->arrayConfig);
                if($this->need_cache()){
                    ob_start();
                }
                extract($this->value,EXTR_OVERWRITE);
                if (!is_file($compile_file) || filemtime($compile_file) < filemtime($this->path())) {
                    $this->compile_tool->vars = $this->value;
                    $this->compile_tool->compile();
                    include $compile_file;
                }else{
                    include ($compile_file);
                }
    
                if($this->need_cache()) {
                    $message = ob_get_contents();
                    file_put_contents($cache_file,$message);
                }
            }else{
                readfile($cache_file);
                $this->debug['cached'] = true;
            }
    
            $this->debug['spend'] = microtime(true)-$this->debug['begin'];
            $this->debug['count'] = count($this->value);
            $this->debug_info();
        }
    
        public function debug_info()
        {
            if ($this->arrayConfig['debug'] == true) {
                echo PHP_EOL.'———debug info———'.PHP_EOL;
                echo "程序运行日期：".date("Y-m-d H:i:s").PHP_EOL;
                echo "模板解析耗时：".$this->debug['spend']."秒".PHP_EOL;
                echo "模板包含标签数目：".$this->debug['count'].PHP_EOL;
                echo "是否使用静态缓存：".$this->debug['cached'].PHP_EOL;
                echo "模板引擎实例参数：";
                var_dump($this->get_config());
            }
        }
    
        public function clean($path=null)
        {
            if($path=null) {
                $path = $this->arrayConfig['compile_dir'];
                $path = glob($path.'*'.$this->arrayConfig['suffix_cache']);
            }else{
                $path = $this->arrayConfig['compile_dir'].md5($path).".html";
            }
            foreach ($path as $item => $value) {
                unlink($value);
            }
        }
    }

接下来是编译类：

//CompileClass.php
    class CompileClass{
        private $template;
        private $content;
        private $compile;
        private $left = '{';
        private $right = '}';
        private $value = array();
        private $T_P = array();
        private $T_R = array();
    
        public function __construct($template,$compile_file,$config)
        {
            $this->template = $template;
            $this->compile = $compile_file;
            $this->content = file_get_contents($template);
            if ($config['php'] == false) {
                $this->T_P[] = '#<\?(=|php|)(.+?)\?>#is';
                $this->T_R[] = '<?\\1\\2?&gt';
            }
            $this->T_P[] = '#\{\\$([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)\}#';
            $this->T_P[] = '#\{(loop|foreach)\\$([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)}#';
            $this->T_P[] = '#\{\/(loop|foreach|if)}#i';
            $this->T_P[] = '#\{([K|V])\}#';
            $this->T_P[] = '#\{if(.*?)\}#i';
            $this->T_P[] = '#\{(else if|elseif)(.*?)\}#i';
            $this->T_P[] = '#\{else\}#i';
            $this->T_P[] = '#\{(\#|\*)(.*?)(\#|\*)\}#';
            $this->T_P[] = '#if\(\\$([a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)#';
    
            $this->T_R[] = "<?php echo \$this->value['\\1'];?>";
            $this->T_R[] = "<?php foreach(\$this->value['\\2'] as \$K => \$this->value['V']){?>";
            $this->T_R[] = "<?php } ?>";
            $this->T_R[] = "<?php echo \$\\1;?>";
            $this->T_R[] = "<?php if(\\1){ ?>";
            $this->T_R[] = "<?php }else if(\\2){ ?>";
            $this->T_R[] = "<?php }else{ ?>";
            $this->T_R[] = " ";
            $this->T_R[] = "if(\$this->value['\\1']";
        }
    
        public function compile()
        {
            $this->c_var2();
            $this->c_static_file();
            file_put_contents($this->compile,$this->content);
        }
    
        public function c_var2()
        {
            $this->content = preg_replace($this->T_P,$this->T_R,$this->content);
        }
    
        public function c_static_file()
        {
            $this->content = preg_replace('#\{\!(.*?)\!\}#','<script src=\\1'.'?t='.time().' ></script>',$this->content);
        }
    
        public function set($name,$value)
        {
            $this->$name = $value;
        }
    
        public function get($name)
        {
            return $this->$name;
        }
    }

然后是模板文件：

//asd.m
    <html>
    {!like.js!}
    {$data},{$person}
    <ul>
        {loop$b}<li>{$V}</li>{/loop}
    </ul>
    {if$data == 'abc'}
    abc
    {elseif$data == 'def'}
    def
    {else}
    {$data}
    {/if}
    {#############################################}
    123456——
    </html>

最后就是调用的代码：

//test.php
    header('Content-type:text/html;charset=utf-8');
    include 'Template.php';
    $tpl = new Template(array('php'=>true,'debug'=>true));
    $tpl->assign("data","hello word");
    $tpl->assign("person","cafe cat");
    $tpl->assign("pai",3.14);
    $arr = array(1,2,3,4,5,"hat",7);
    $tpl->assign('b',$arr);
    $tpl->show('asd');
    die;

目录结构如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2x1eWFyYW4_size_16_color_FFFFFF_t_70][]

模板文件放在这个位置：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2x1eWFyYW4_size_16_color_FFFFFF_t_70 1][]

最后我们会在下图位置看到编译后的文件：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2x1eWFyYW4_size_16_color_FFFFFF_t_70 2][]

从某种意义上来看的话，数据库也可以看做是优化过的、高效的文件存储的一种，我们对于变动少的，体积比较大的数据可以使用文件存储，反之，数据库比较合适，数据库比文件存储高级的地方就是，它解决了文件存储中很难解决的数据同步和锁的问题。所以说，是用什么存储，看大家的意思的，最重要的还是因地制宜，实现需求。

好啦，本次记录就到这里了。

如果感觉不错的话，请多多点赞支持哦。。。

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