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根据文件头检测文件类型
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：
function checkFileType($fileName){ $file = fopen($fileName, "rb"); $bin = fread($file, 2); //只读2字节 fclose($file); 老品牌娱乐城 // 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：
/*通过文件名，获得文件类型* *@author chengmo QQ:8292669* *@copyright http://www.cnblogs.com/chengmo 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：
$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;根据文件头检测文件类型
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