修复扩展名bug

@@ -50,11 +50,13 @@ class Attachment {
             return $this->extension;
         }
         // 在 mime文件类型中查找
-        if(is_file('mime.types') && $this->getFileType()){
-            $type = file_get_contents('mime.types');
-            $type = explode("\r\n",$type);
+        $a = is_file(__DIR__.'/mime.types');
+        if($a && $this->getFileType()){
+            $type = file_get_contents(__DIR__.'/mime.types');
+            $type = explode("\n",$type);
             foreach ($type as $item){
                 if(stripos($item,$this->getFileType())===0){
+                    $item = str_replace("\t"," ",$item);
                     list($t,$e) = explode(' ',$item,2);
                     $e = trim($e);
                     if($e){