VB.net 获取文件的MD5值

Imports System.IO
Imports System.Security.Cryptography

Public Shared Function _MD5(ByVal strSource As String) As String
    Dim fstream As New FileStream(strSource, FileMode.Open, FileAccess.Read)
    Dim dataToHash(fstream.Length - 1) As Byte
    fstream.Read(dataToHash, 0, fstream.Length)
    fstream.Close()
    Dim hashvalue As Byte() = CType(CryptoConfig.CreateFromName("MD5"), HashAlgorithm).ComputeHash(dataToHash)
    Dim i As Integer
    Dim result As String = ""
    For i = 0 To hashvalue.Length - 1
        result += Hex(hashvalue(i)).ToLower
    Next
    Return result
End Function