Common methods for traversing directory files in PHP
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.; }
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($handle); }
算法3.函数系
function tree($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"; $mydir->close(); } tree("C:\\Inetpub\\wwwroot\\test\\");
算法4.函数系II
function listDir($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\\");
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\\"));
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)";
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.; }
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。
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