PHP如何下载远程文件到指定目录

PHP用curl可以轻松实现下载远程文件到指定目录：

<?php
class Download
{
   public static function get($url, $file)
   {
      return file_put_contents($file, file_get_contents($url));
   }
   public static function curlGet($url, $file)
   {
      $ch = curl_init();
      curl_setopt($ch, CURLOPT_POST, 0); 
      curl_setopt($ch,CURLOPT_URL,$url); 
      curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
      $file_content = curl_exec($ch);
      curl_close($ch);
      $downloaded_file = fopen($file, 'w');
      fwrite($downloaded_file, $file_content);
      fclose($downloaded_file);
   }
   public static function openGet($url, $file)
   {
      $in = fopen($url, "rb");
      $out = fopen($file, "wb");
      while ($chunk = fread($in,8192))
      {
         fwrite($out, $chunk, 8192);
      }
      fclose($in);
      fclose($out);
   }

   /**
   *
   * 创建目录，支持递归创建目录
   * @param String $dirName 要创建的目录
   * @param int $mode 目录权限
   */
  public static function smkdir($dirName , $mode = 0777) {
     $dirs = explode('/' , str_replace('\\' , '/' , $dirName));
     $dir = '';
     foreach ($dirs as $part) {
        $dir.=$part . '/';
        if ( ! is_dir($dir) && strlen($dir) > 0) {
           if ( ! mkdir($dir , $mode)) {
              return false;
           }
           if ( ! chmod($dir , $mode)) {
              return false;
           }
        }
     }
     return true;
   }
}