Method To Get Mime Type Of A File Based On Extension

I had to create a file binary writer that would force a file to download rather than open in a new window. I tried to identify each files MIME type based on data I found on the web. However, after searching for a while, I couldn't (and probably never will) find a complete list. So I wrote this method to get the MIME type from the Registry.

C# Code

/// <summary>
/// Attempt to get the system value file type
/// </summary>
/// <param name="_ext"></param>
/// <returns></returns>
/// <remarks></remarks>
public static string GetMimeType(string _ext)
{
 
    string mimeType = string.Empty;
 
    Microsoft.Win32.RegistryKey regKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(_ext);
 
 
    if (regKey != null) {
        string type = (string)regKey.GetValue("Content Type");
 
        if (type != null) {
            mimeType = type;
        }
 
    }
 
    if (mimeType == string.Empty)
        mimeType = GetFileType(_ext);
 
    return mimeType;
 
}

Code (markup):

VB.Net Code

''' <summary>
    ''' Attempt to get the system value file type
    ''' </summary>
    ''' <param name="_ext"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Shared Function GetMimeType(ByVal _ext As String) As String
 
        Dim mimeType As String = String.Empty
 
        Dim regKey As Microsoft.Win32.RegistryKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(_ext)
 
        If regKey IsNot Nothing Then
 
            Dim type As String = DirectCast(regKey.GetValue("Content Type"), String)
 
            If type IsNot Nothing Then
                mimeType = type
            End If
 
        End If
 
        If mimeType = String.Empty Then mimeType = GetFileType(_ext)
 
        Return mimeType
 
    End Function

Code (markup):