“IOException was unhandled”，错误不断出现

Question

我遇到了这个问题，它似乎并没有消失。我在 vb.net 中完成了一个代码，我在其中流式传输文件，但我不断收到该错误

“IOException was unhandled”进程无法访问文件 'C:\Users\Lenovo\documents\visual studio 2010\Projects\File streaming\File Streaming\bin\Debug\banking.xls' 因为它正在 被另一个进程使用。

代码如下：

Imports System.IO

Imports System.Windows.Forms.Form
Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub

    Private Sub btnDisplay_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDisplay.Click

        Dim FileStr As New FileStream("banking.xls", FileMode.Create, FileAccess.Write)

        Dim a As New StreamWriter(FileStr)

        'a.WriteLine("File should be displayed in the RTB............")
        'a.Close()

       **ERROR APPEARS HERE**     
        FileStr = New FileStream("banking.xls", FileMode.Open, FileAccess.Read)

        Dim i As New StreamReader(FileStr)

        i.BaseStream.Seek(0, SeekOrigin.Begin)

        If i.Peek() > -1 Then

            rtbDisplay.Text &= i.ReadLine()

        End If
        i.Close()

    End Sub

    Private Sub btnClear_Click(sender As System.Object, e As System.EventArgs) Handles btnClear.Click

        rtbDisplay.Text = ""

    End Sub

    Private Sub btnExit_Click(sender As System.Object, e As System.EventArgs) Handles btnExit.Click

        Me.Close()

    End Sub

    Private Function FileStream() As Object
        Throw New NotImplementedException
    End Function

End Class

Answer 1

FileStream 和 StreamWriter 是 IDisposable 对象，应该在你用完它们时释放它们。当 IDisposable 具有本地范围时，最好使用 Using 块创建它们。

Sub Main()
    Using FileStr As New FileStream("banking.xls", FileMode.Create, FileAccess.Write)
        Using a As New StreamWriter(FileStr)
            a.WriteLine("File should be displayed in the RTB............")
        End Using
    End Using

    Using FileStr = New FileStream("banking.xls", FileMode.Open, FileAccess.Read)
        Dim i As New StreamReader(FileStr)
    End Using
End Sub

不过，我不知道您为什么要将文本写入这样的 xls 文件。如果你在操作 Excel 文件，你应该看看Open Xml 或Microsoft Office Interop