input file 获取不到Request.Files 解决办法

<input type="file" name="xxxxxxx"/>必须有“name”属性，否则在后台代码中用Request.Files是取不到值的

后台读取文件代码：

　　　　　HttpFileCollection httpFileCollection = HttpContext.Current.Request.Files;
                if (httpFileCollection.Count > 0)
                {
                    HttpPostedFile file = httpFileCollection[0];
                   
                     StreamReader reader = new StreamReader(file.InputStream);
                     StringBuilder strLicense = new StringBuilder();
                     do
                     {
                         strLicense.AppendLine(reader.ReadLine());
                     } while (!reader.EndOfStream);

return strLicense.ToString();
                   
                }