抛出异常：Hotel.dll 中的“System.IO.FileNotFoundException”

Question

我是使用 vb.net 的初学者，在这个问题上，我想将 Oracle 12c 连接到我的 Visual Basic 应用程序。我认为一切都正确，应用程序也可以运行。但是当我想测试连接时，我的控制台显示错误Exception thrown: 'System.IO.FileNotFoundException' in Hotel.dll

这是我的代码：

Imports Oracle.DataAccess.Client
Public Class Form1
    Dim con As New OracleConnection
    Dim cmd As New OracleCommand
    Dim sql As String

    Private Sub btntest_Click(sender As Object, e As EventArgs) Handles btntest.Click
        dbAccess()
    End Sub

    Private Sub dbAccess()
        con = New OracleConnection
        Try
            con.ConnectionString = "Data Source=(DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = pdborcl))); user id=admin;password=admin"
            con.Open()
            MsgBox("Connection OK")
        Catch ex As Exception
            MsgBox("Connection Fail")
        End Try
    End Sub
End Class

这是错误：

https://i.ibb.co/443qTQ0/Untitled.png https://i.ibb.co/84D8Rty/Untitledx.png

Answer 1

连接和命令需要在使用它们的方法中的使用块中本地声明。它们包含类在 Dispose 方法中释放的非托管资源。即使出现错误，也使用块关闭并处置这些对象。

在异常上调用 ToString 应该会为您提供有关问题的更多详细信息。

有关连接问题，请参阅https://www.connectionstrings.com/oracle-data-provider-for-net-odp-net/

Private OracleConstring As String = "Data Source=(DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))(CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = pdborcl))); user id=admin;password=admin"

Private Sub dbAccess()
    Using con As New OracleConnection(OracleConstring)
        Try
            con.Open()
            MsgBox("Connection OK")
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Using
End Sub