PHP如何根据文件头检测文件类型实例代码


						前言

什么是文件头部Bom？ 说白了，就是在保存文件的时候，文件前面会多出一串隐藏的字符，文件签名一般都在文件的头部，如果你用十六进制方式查看文件，你就可以看到文件的一些签名信息。如用uestudio以十六进制方式查看zip格式的文件，其文件内容头部有50 4B 03 04这样的十六进制信息。同理jpg文件状况有FF D8 FF E0 xx xx 4A 46这样的十六进制信息，其实这此十六进制都是表示一些特殊字条。

php怎么样验证文件类型？

先来看一个简单的方法：





<?php

function checkFileType($fileName){ 

  $file = fopen($fileName, "rb"); 

  $bin = fread($file, 2); //只读2字节 

  fclose($file); 

 // C为无符号整数，网上搜到的都是c，为有符号整数，这样会产生负数判断不正常

  $strInfo = @unpack("C2chars", $bin);

  $typeCode = intval($strInfo['chars1'].$strInfo['chars2']); 

  $fileType = ''; 



 switch( $typeCode )

 {

 case '255216':

 return $typeCode. ' : ' .'jpg';

 break;

 case '7173':

 return $typeCode. ' : ' .'gif';

 break;

 case '13780':

 return $typeCode. ' : ' .'png';

 break;

 case '6677':

 return $typeCode. ' : ' .'bmp';

 break;

 case '7790':

 return $typeCode. ' : ' .'exe';

 break;

 case '7784':

 return $typeCode. ' : ' .'midi';

 break;

 case '8297':

 return $typeCode. ' : ' .'rar';

 break;

 default:

 return $typeCode. ' : ' .'Unknown';

 break;

 }

 //return $typeCode;

 }



$file_name = '11.doc';

echo checkFileType($file_name);



下来提供一个类的实现：





<?php

/*通过文件名，获得文件类型*

 *@author chengmo QQ:8292669*

 *@copyright <a href="http://www.cnblogs.com/chengmo">http://www.cnblogs.com/chengmo</a> 2010-10-17

 *@version 0.1

 *$filename="d:/1.png";echo cFileTypeCheck::getFileType($filename); 打印：png

 */

class cFileTypeCheck

{

  private static $_TypeList=array();

  private static $CheckClass=null;

  private function __construct($filename)

  {

    self::$_TypeList=$this->getTypeList();

  }



  /**

   *处理文件类型映射关系表*

   *

   * @param string $filename 文件类型

   * @return string 文件类型，没有找到返回：other

   */

  private function _getFileType($filename)

  {

    $filetype="other";

    if(!file_exists($filename)) throw new Exception("no found file!");

    $file = @fopen($filename,"rb");

    if(!$file) throw new Exception("file refuse!");

    $bin = fread($file, 15); //只读15字节 各个不同文件类型，头信息不一样。

    fclose($file);



    $typelist=self::$_TypeList;

    foreach ($typelist as $v)

    {

      $blen=strlen(pack("H*",$v[0])); //得到文件头标记字节数

      $tbin=substr($bin,0,intval($blen)); ///需要比较文件头长度



      if(strtolower($v[0])==strtolower(array_shift(unpack("H*",$tbin))))

      {

        return $v[1];

      }

    }

    return $filetype;

  }



  /**

   *得到文件头与文件类型映射表*

   *

   * @return array array(array('key',value)...)

   */

  public function getTypeList()

  {

    return array(array("FFD8FFE1","jpg"),

    array("89504E47","png"),

    array("47494638","gif"),

    array("49492A00","tif"),

    array("424D","bmp"),

    array("41433130","dwg"),

    array("38425053","psd"),

    array("7B5C727466","rtf"),

    array("3C3F786D6C","xml"),

    array("68746D6C3E","html"),

    array("44656C69766572792D646174","eml"),

    array("CFAD12FEC5FD746F","dbx"),

    array("2142444E","pst"),

    array("D0CF11E0","xls/doc"),

    array("5374616E64617264204A","mdb"),

    array("FF575043","wpd"),

    array("252150532D41646F6265","eps/ps"),

    array("255044462D312E","pdf"),

    array("E3828596","pwl"),

    array("504B0304","zip"),

    array("52617221","rar"),

    array("57415645","wav"),

    array("41564920","avi"),

    array("2E7261FD","ram"),

    array("2E524D46","rm"),

    array("000001BA","mpg"),

    array("000001B3","mpg"),

    array("6D6F6F76","mov"),

    array("3026B2758E66CF11","asf"),

    array("4D546864","mid"));

  }





  public static function getFileType($filename)

  {

    if(!self::$CheckClass) self::$CheckClass=new self($filename);

    $class=self::$CheckClass;

    return $class->_getFileType($filename);

  }



}



$filename="22.jpg";

echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn";

$filename="11.doc";

echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn";



或者可以这么检测：





<?php

$filename = '22.jpg';



$extname = strtolower(substr($filename, strrpos($filename, '.') + 1));

echo $extname.'<br />';

$file = @fopen($filename, 'rb');

  if ($file)

  {

    $str = @fread($file, 0x400); // 读取前 1024 个字节

 echo substr($str, 0, 4);

    @fclose($file);

  }

 if (substr($str, 0, 4) == 'MThd' && $extname != 'txt')

    {

      $format = 'mid';

    }

    elseif (substr($str, 0, 4) == 'RIFF' && $extname == 'wav')

    {

      $format = 'wav';

    }

    elseif (substr($str ,0, 3) == "/xFF/xD8/xFF")

    {

      $format = 'jpg';

    }

    elseif (substr($str ,0, 4) == 'GIF8' && $extname != 'txt')

    {

      $format = 'gif';

    }

    elseif (substr($str ,0, 8 ) == "/x89/x50/x4E/x47/x0D/x0A/x1A/x0A")

    {

      $format = 'png';

    }

    elseif (substr($str ,0, 2) == 'BM' && $extname != 'txt')

    {

      $format = 'bmp';

    }

    elseif ((substr($str ,0, 3) == 'CWS' || substr($str ,0, 3) == 'FWS') && $extname != 'txt')

    {

      $format = 'swf';

    }

    elseif (substr($str ,0, 4) == "/xD0/xCF/x11/xE0")

    {  // D0CF11E == DOCFILE == Microsoft Office Document

      if (substr($str,0x200,4) == "/xEC/xA5/xC1/x00" || $extname == 'doc')

      {

        $format = 'doc';

      }

      elseif (substr($str,0x200,2) == "/x09/x08" || $extname == 'xls')

      {

        $format = 'xls';

      } elseif (substr($str,0x200,4) == "/xFD/xFF/xFF/xFF" || $extname == 'ppt')

      {

        $format = 'ppt';

      }

    } elseif (substr($str ,0, 4) == "PK/x03/x04")

    {

      $format = 'zip';

    } elseif (substr($str ,0, 4) == 'Rar!' && $extname != 'txt')

    {

      $format = 'rar';

    } elseif (substr($str ,0, 4) == "/x25PDF")

    {

      $format = 'pdf';

    } elseif (substr($str ,0, 3) == "/x30/x82/x0A")

    {

      $format = 'cert';

    } elseif (substr($str ,0, 4) == 'ITSF' && $extname != 'txt')

    {

      $format = 'chm';

    } elseif (substr($str ,0, 4) == "/x2ERMF")

    {

      $format = 'rm';

    } elseif ($extname == 'sql')

    {

      $format = 'sql';

    } elseif ($extname == 'txt')

    {

      $format = 'txt';

    }



 echo $format;



总结

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