php检测下传excel文件类型

	/**	 * Detect upload file type	 * 	 * @param array $file        		 * @return bool $flag	 */	private function detectUploadFileMIME($file) {		// 1.through the file extension judgement 03 or 07		$flag = 0;		$file_array = explode ( ".", $file ["name"] );		$file_extension = strtolower ( array_pop ( $file_array ) );				// 2.through the binary content to detect the file		switch ($file_extension) {			case "xls" :				// 2003 excel				$fh = fopen ( $file ["tmp_name"], "rb" );				$bin = fread ( $fh, 8 );				fclose ( $fh );				$strinfo = @unpack ( "C8chars", $bin );				$typecode = "";				foreach ( $strinfo as $num ) {					$typecode .= dechex ( $num );				}				if ($typecode == "d0cf11e0a1b11ae1") {					$flag = 1;				}				break;			case "xlsx" :				// 2007 excel				$fh = fopen ( $file ["tmp_name"], "rb" );				$bin = fread ( $fh, 4 );				fclose ( $fh );				$strinfo = @unpack ( "C4chars", $bin );				$typecode = "";				foreach ( $strinfo as $num ) {					$typecode .= dechex ( $num );				}				echo $typecode;				if ($typecode == "504b34") {					$flag = 1;				}				break;		}				// 3.return the flag		return $flag;	}