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： 01 function checkFileType($fileName){ 02 $file = fopen($fileName, "rb"); 03 $bin = fread($file, 2); //只读2字节 04 fclose($file); 05 // 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 06 $strInfo = @unpack("C2chars", $bin); 07 $typeCode = intval($strInfo['chars1'].$strInfo['chars2']); 08 $fileType = ''; 09 10 switch( $typeCode ) 11 { 12 case '255216': 13 return $typeCode. ' : ' .'jpg'; 14 break; 15 case '7173': 16 return $typeCode. ' : ' .'gif'; 17 break; 18 case '13780': 19 return $typeCode. ' : ' .'png'; 20 break; 21 case '6677': 22 return $typeCode. ' : ' .'bmp'; 23 break; 24 case '7790': 25 return $typeCode. ' : ' .'exe'; 26 break; 27 case '7784': 28 return $typeCode. ' : ' .'midi'; 29 break; 30 case '8297': 31 return $typeCode. ' : ' .'rar'; 32 break; 33 default: 34 return $typeCode. ' : ' .'Unknown'; 35 break; 36 } 37 //return $typeCode; 38 } 39 40 $file_name = '11.doc'; 41 echo checkFileType($file_name); 下来提供一个类的实现： 01 /*通过文件名，获得文件类型* 02 *@author chengmo QQ:8292669* 03 *@copyright <a href="http://www.cnblogs.com/chengmo">http://www.cnblogs.com/chengmo</a> 2010-10-17 04 *@version 0.1 05 *$filename="d:/1.png";echo cFileTypeCheck::getFileType($filename); 打印：png 06 */ 07 class cFileTypeCheck 08 { 09 private static $_TypeList=array(); 10 private static $CheckClass=null; 11 private function __construct($filename) 12 { 13 self::$_TypeList=$this->getTypeList(); 14 } 15 16 /** 17 *处理文件类型映射关系表* 18 * 19 * @param string $filename 文件类型 20 * @return string 文件类型，没有找到返回：other 21 */ 22 private function _getFileType($filename) 23 { 24 $filetype="other"; 25 if(!file_exists($filename)) throw new Exception("no found file!"); 26 $file = @fopen($filename,"rb"); 27 if(!$file) throw new Exception("file refuse!"); 28 $bin = fread($file, 15); //只读15字节 各个不同文件类型，头信息不一样。 29 fclose($file); 30 31 $typelist=self::$_TypeList; 32 foreach ($typelist as $v) 33 { 34 $blen=strlen(pack("H*",$v[0])); //得到文件头标记字节数 35 $tbin=substr($bin,0,intval($blen)); ///需要比较文件头长度 36 37 if(strtolower($v[0])==strtolower(array_shift(unpack("H*",$tbin)))) 38 { 39 return $v[1]; 40 } 41 } 42 return $filetype; 43 } 44 45 /** 46 *得到文件头与文件类型映射表* 47 * 48 * @return array array(array('key',value)...) 49 */ 50 public function getTypeList() 51 { 52 return array(array("FFD8FFE1","jpg"), 53 array("89504E47","png"), 54 array("47494638","gif"), 55 array("49492A00","tif"), 56 array("424D","bmp"), 57 array("41433130","dwg"), 58 array("38425053","psd"), 59 array("7B5C727466","rtf"), 60 array("3C3F786D6C","xml"), 61 array("68746D6C3E","html"), 62 array("44656C69766572792D646174","eml"), 63 array("CFAD12FEC5FD746F","dbx"), 64 array("2142444E","pst"), 65 array("D0CF11E0","xls/doc"), 66 array("5374616E64617264204A","mdb"), 67 array("FF575043","wpd"), 68 array("252150532D41646F6265","eps/ps"), 69 array("255044462D312E","pdf"), 70 array("E3828596","pwl"), 71 array("504B0304","zip"), 72 array("52617221","rar"), 73 array("57415645","wav"), 74 array("41564920","avi"), 75 array("2E7261FD","ram"), 76 array("2E524D46","rm"), 77 array("000001BA","mpg"), 78 array("000001B3","mpg"), 79 array("6D6F6F76","mov"), 80 array("3026B2758E66CF11","asf"), 81 array("4D546864","mid")); 82 } 83 84 85 public static function getFileType($filename) 86 { 87 if(!self::$CheckClass) self::$CheckClass=new self($filename); 88 $class=self::$CheckClass; 89 return $class->_getFileType($filename); 90 } 91 92 } 93 94 $filename="22.jpg"; 95 echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn"; 96 $filename="11.doc"; 97 echo $filename,"t",cFileTypeCheck::getFileType($filename),"rn"; 或者可以这么检测： 01 $filename = '22.jpg'; 02 03 $extname = strtolower(substr($filename, strrpos($filename, '.') + 1)); 04 echo $extname.'<br />'; 05 $file = @fopen($filename, 'rb'); 06 if ($file) 07 { 08 $str = @fread($file, 0x400); // 读取前 1024 个字节 09 echo substr($str, 0, 4); 10 @fclose($file); 11 } 12 if (substr($str, 0, 4) == 'MThd' && $extname != 'txt') 13 { 14 $format = 'mid'; 15 } 16 elseif (substr($str, 0, 4) == 'RIFF' && $extname == 'wav') 17 { 18 $format = 'wav'; 19 } 20 elseif (substr($str ,0, 3) == "/xFF/xD8/xFF") 21 { 22 $format = 'jpg'; 23 } 24 elseif (substr($str ,0, 4) == 'GIF8' && $extname != 'txt') 25 { 26 $format = 'gif'; 27 } 28 elseif (substr($str ,0, 8 ) == "/x89/x50/x4E/x47/x0D/x0A/x1A/x0A") 29 { 30 $format = 'png'; 31 } 32 elseif (substr($str ,0, 2) == 'BM' && $extname != 'txt') 33 { 34 $format = 'bmp'; 35 } 36 elseif ((substr($str ,0, 3) == 'CWS' || substr($str ,0, 3) == 'FWS') && $extname != 'txt') 37 { 38 $format = 'swf'; 39 } 40 elseif (substr($str ,0, 4) == "/xD0/xCF/x11/xE0") 41 { // D0CF11E == DOCFILE == Microsoft Office Document 42 if (substr($str,0x200,4) == "/xEC/xA5/xC1/x00" || $extname == 'doc') 43 { 44 $format = 'doc'; 45 } 46 elseif (substr($str,0x200,2) == "/x09/x08" || $extname == 'xls') 47 { 48 $format = 'xls'; 49 } elseif (substr($str,0x200,4) == "/xFD/xFF/xFF/xFF" || $extname == 'ppt') 50 { 51 $format = 'ppt'; 52 } 53 } elseif (substr($str ,0, 4) == "PK/x03/x04") 54 { 55 $format = 'zip'; 56 } elseif (substr($str ,0, 4) == 'Rar!' && $extname != 'txt') 57 { 58 $format = 'rar'; 59 } elseif (substr($str ,0, 4) == "/x25PDF") 60 { 61 $format = 'pdf'; 62 } elseif (substr($str ,0, 3) == "/x30/x82/x0A") 63 { 64 $format = 'cert'; 65 } elseif (substr($str ,0, 4) == 'ITSF' && $extname != 'txt') 66 { 67 $format = 'chm'; 68 } elseif (substr($str ,0, 4) == "/x2ERMF") 69 { 70 $format = 'rm'; 71 } elseif ($extname == 'sql') 72 { 73 $format = 'sql'; 74 } elseif ($extname == 'txt') 75 { 76 $format = 'txt'; 77 } 78 79 echo $format;
