Question

我正在使用本地.mdf文件，并且我对数据库执行了一些查询，并且我正在使用USING块来确保正确处理SqlConnection和SqlReader。

然后我尝试读取文件的数据以生成文件的MD5哈希，但它说该文件仍在使用中。

代码并不是最干净的，这是我第一次在VB.NET应用程序中使用Sql。

SQL Insert：

Dim finalW As String = ""
Dim finalO() As String
Dim currentcounter As Integer = 0
For Each Dir As String In System.IO.Directory.GetDirectories(Pathfinder)
    Dim dirInfo As New System.IO.DirectoryInfo(Dir)
    Dim temp As New List(Of String)
    For Each currentFile In Directory.GetFiles(Pathfinder & "\" & dirInfo.Name & "\", "*.png", SearchOption.TopDirectoryOnly)
        temp.Add(Path.GetFileName(currentFile))
    Next
    If temp.Count <> 0 Then
        finalW = temp.Find(AddressOf GetNewIcon)
        finalO = temp.FindAll(AddressOf GetOldIcon).ToArray
        If finalW <> "" Then
            Using con As New SqlClient.SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=""" & PathFinal & "ImaginiDB.mdf"";Integrated Security=True")
                con.Open()
                Using cmd = con.CreateCommand()
                    cmd.CommandType = CommandType.Text
                    cmd.CommandText = "INSERT NewIcon (Name) VALUES ('" & finalW.Trim() & "')"
                    cmd.Connection = con
                    cmd.ExecuteNonQuery()
                End Using
                currentcounter = currentcounter + 1
                Dim Id As String = ""
                Using command = con.CreateCommand()
                    command.CommandType = CommandType.Text
                    command.CommandText = "SELECT * FROM NewIcon WHERE Name='" & finalW & "'"
                    Using reader As SqlDataReader = command.ExecuteReader()
                        While reader.Read()
                            Id = reader(0)
                        End While
                    End Using
                End Using
                For Each item As String In finalO
                    Using cmd2 = con.CreateCommand()
                        cmd2.CommandType = CommandType.Text
                        cmd2.CommandText = "INSERT OldIcon (NID,Name) VALUES ('" & Id & "','" & item.ToString.Trim() & "')"
                        cmd2.Connection = con
                        cmd2.ExecuteNonQuery()
                    End Using
                    currentcounter = currentcounter + 1
                Next
                Dim cur As Long = currentcounter * 100 / counter
                SetProgress(cur)
            End Using
        End If
    End If
Next
GC.Collect()
GC.WaitForPendingFinalizers()
SetLabel4Text("FINISHED IMPORT", Color.Red)

MD5生成在此过程完成后运行：

Public Function GenMD5(ByVal Filename As String) As String
    Dim MD5 = System.Security.Cryptography.MD5.Create
    Dim Hash As Byte()
    Dim sb As New System.Text.StringBuilder
    Using st As New IO.FileStream(Filename, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)
        Hash = MD5.ComputeHash(st)
    End Using
    For Each b In Hash
        sb.Append(b.ToString("X2"))
    Next
    Return sb.ToString
End Function

Answer 1

正如@jmcilhinney的评论中提到的那样 MSDN说，不同的连接使用不同的池：

首次打开连接时，会创建一个连接池关于将池与池相关联的精确匹配算法连接中的连接字符串。

因此我决定实施该方法：

SqlConnection.ClearPool(connection As SqlConnection)

我把它放在我的END使用之前：

    Dim cur As Long = currentcounter * 100 / counter
    SetProgress(cur)
    SqlConnection.ClearPool(con)
End Using

vb.net使用SqlConnection不会释放文件使用

1 个答案: