php通过获取头信息判断图片类型 $filename = '617.gif' ; function pictype ( $file ) { /*$png_header = /x89/x50/x4e/x47/x0d/x0a/x1a/x0a; $jpg_header = /xff/xd8;*/ $header = file_get_contents ( $file , 0 , null , 0 , 5 ); //echo bin2hex($header); if ( $header { 0 }. $header { 1 }== /x89/x50 ) { return 'png' ; } else if( $header { 0 }. $header { 1 } == /xff/xd8 ) { return 'jpeg' ; } else if( $header { 0 }. $header { 1 }. $header { 2 } == /x47/x49/x46 ) { if( $header { 4 } == /x37 ) return 'gif87' ; else if( $header { 4 } == /x39 ) return 'gif89' ; } } echo pictype ( $filename );