1
我正在使用本地.mdf文件,并执行一些查询到数据库,我使用USING块来确保SqlConnection和SqlReader被正确处置。vb.net使用SqlConnection不释放文件使用
然后我尝试读取文件的数据以生成文件的MD5散列,但它说文件仍在使用中。
代码不是最清洁的,这是我第一次使用VB.NET应用程序中的Sql工作。
SQL插入:
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代追着这个过程完成:
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
有时候,con.close()结束前使用可以帮助...不确定,如果这有助于你的情况。 – muffi
@ muffi刚刚在每次使用结束时尝试过,但仍然得到错误。 – Mederic
您应该阅读ADO.NET中的连接池。 'SqlConnection'是一个轻量级的对象,实际的数据库连接存在于较低的级别。连接池意味着多个'SqlConnection'对象将使用相同的底层连接对象,并且系统会在关闭SqlConnection后加速打开一段时间,以加速后续的使用。 – jmcilhinney