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Common methods for traversing directory files in PHP

Jun 02, 2018 pm 01:57 PM
php Commonly used method

这篇文章主要介绍了PHP遍历目录文件的常用方法,结合实例形式总结分析了php针对文件与目录的常用遍历技巧与运行效率,具有一定参考借鉴价值,需要的朋友可以参考下

本文实例总结了PHP遍历目录文件的常用方法。分享给大家供大家参考,具体如下:

测试算法(源代码经过本站工具http://tools.jb51.net/code/jb51_php_format进行格式化处理,以便于读者阅读)

算法1.简短系

foreach(glob('*.*') as $filename)
{
  echo 'Filename:'.$filename.;
}
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算法2.规矩系

if($handle = opendir('C:\\Inetpub\\wwwroot\\test\\')){
  echo "Files:\n";
  while (false !== ($file = readdir($handle))){
    echo "$file\n";
  }
  closedir($handle);
}
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算法3.函数系

function tree($directory)
{
  $mydir=dir($directory);
  while($file=$mydir->read()){
    if((is_dir("$directory/$file")) AND ($file!=".") AND ($file!=".."))
    {
      echo "$file\n";
      tree("$directory/$file");
    } else
    echo "$file\n";
  }
  echo "\n";
  $mydir->close();
}
tree("C:\\Inetpub\\wwwroot\\test\\");
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算法4.函数系II

function listDir($dir){
  if(is_dir($dir)){
    if ($dh = opendir($dir)) {
      while (($file= readdir($dh)) !== false){
        if((is_dir($dir."/".$file)) && $file!="." && $file!=".."){
          echo "文件名:",$file;
          listDir($dir."/".$file."/");
        } else{
          if($file!="." && $file!=".."){
            echo $file;
          }
        }
      }
      closedir($dh);
    }
  }
}
listDir("C:\\Inetpub\\wwwroot\\test\\");
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算法5.递归系

function file_list($dir,$pattern="")
{
  $arr=array();
  $dir_handle=opendir($dir);
  if($dir_handle)
  {
    while(($file=readdir($dir_handle))!==false)
    {
      if($file==='.' || $file==='..')
      {
        continue;
      }
      $tmp=realpath($dir.'/'.$file);
      if(is_dir($tmp))
      {
        $retArr=file_list($tmp,$pattern);
        if(!emptyempty($retArr))
        {
          $arr[]=$retArr;
        }
      } else
      {
        if($pattern==="" || preg_match($pattern,$tmp))
        {
          $arr[]=$tmp;
        }
      }
    }
    closedir($dir_handle);
  }
  return $arr;
}
print_r(file_list("C:\\Inetpub\\wwwroot\\test\\"));
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测试方法

我们采取在测试代码的头部和尾部添加如下的内容来检测执行时间,并测试5次取平均结果作为最终成绩。

$stime=microtime(true);
//测试代码
//......
//......
$etime=microtime(true);
$total=($etime-$stime)*1000;
echo "{$total} Millisecond(s)";
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测试结果:

算法1

算法1在浏览器能正确输出所有项目,5次测验耗费的时间分别是:

平均用时=3803.618621824 毫秒

算法2

算法2在浏览器也能正确输出所有项目,但在开头会给出“..”(上级目录)的信息。5次测验耗费的时间分别是:

平均用时=381.0853481294 毫秒

算法3

算法3在浏览器能正确输出所有项目,也仍会给出“..”(上级目录)的信息。5次测验耗费的时间分别是:

平均用时=24299.2805485 毫秒

算法4

算法4和算法3类似,在浏览器能正确输出所有项目,5次测验耗费的时间分别是:

平均用时=24020.66812516 毫秒

算法5

算法5曾一度让我以为IIS又出问题了。虽说它在浏览器能正确输出所有项目,但数据的结果默认为数组。5次测验耗费的时间分别是:

平均用时=61411.31243706 毫秒

测试总结

根据测试结果,我们很容易得出下面的速度排名。

算法2 > 算法1 > 算法4 > 算法3 > 算法5

为什么算法2要比其他算法都高效一些呢?

实际上是因为算法中只使用了php中内置用来读取目录内容的函数“readdir()” 。除了算法1以外,其他算法在引用readdir()的时候,为了弥补函数的先天不足,干了很多其他的事情。

如果说,我们需要指定扩展名的列举目录内所有文件的话。Rt推荐使用算法1的模式,我们将代码写成这样就可以了。

foreach(glob('*.需要的扩展名') as $filename)
{
  echo 'Filename:'.$filename.;
}
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结语

不管作为一个代码新手还是一个资深的程序员,在堆砌代码的时候,更应该关注程序的效率和安全。

请不要忽略任何一种可能,也请不要让孩子般的代码成为拖累服务器的罪魁祸首。

相关推荐:

PHP遍历算法的总结

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