asp.net-mvc – 当我不知道内容类型时如何返回文件结果

这是从控制器操作返回FilePathResult的完整示例：

string filePysicalPath,fileName; //these need to be set to your values.

var reg = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey( Path.GetExtension( filename ).ToLower() );
string contentType = "application/unknown";

if ( reg != null )
{
    string registryContentType = reg.GetValue( "Content Type" ) as string;

    if ( !String.IsNullOrWhiteSpace( registryContentType ) )
    {
        contentType = registryContentType;
    }
}

return File( filePysicalPath,contentType,filename );