08 读取缓存方式开发首页接口

一：读取缓存方式开发首页接口
  
流程图：从数据库获取信息--->>>封装[同时把一份数据存入缓存]----->>>>返回数据
                         

file.php

<?php

class File {
    private $_dir;

    const EXT = '.txt';

    public function __construct() {
        $this->_dir = dirname(__FILE__) . '/files/';
    }
    public function cacheData($key, $value = '', $cacheTime = 0) {
        $filename = $this->_dir  . $key . self::EXT;

        if($value !== '') { // 将value值写入缓存
            if(is_null($value)) {
                return @unlink($filename);
            }
            $dir = dirname($filename);
            if(!is_dir($dir)) {
                mkdir($dir, 0777);
            }

            $cacheTime = sprintf('%011d', $cacheTime);
            return file_put_contents($filename,$cacheTime . json_encode($value));
        }

        if(!is_file($filename)) {
            return FALSE;
        } 
        $contents = file_get_contents($filename);
        $cacheTime = (int)substr($contents, 0 ,11);
        $value = substr($contents, 11);
        if($cacheTime !=0 && ($cacheTime + filemtime($filename) < time())) {
            unlink($filename);
            return FALSE;
        }
        return json_decode($value, true);
        
    }
}

$file = new File();

echo $file->cacheData('test1');