asp.net文本框未更新背后的表单代码

Question

So I do want to update my TextBox called "ServerDataArea" in a thread running in code behind.

form:

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:TextBox id="ServerDataArea" TextMode="multiline" Columns="50" Rows="15" runat="server" Enabled="false" />
        <br />
        <asp:TextBox ID="Message" runat="server" ></asp:TextBox>
        <asp:Button ID="SendMessage" runat="server" OnClick="appendMessage_Click" Text="Send" />
    </ContentTemplate>
</asp:UpdatePanel>

This is how my code behind does to update this textbox:

public delegate void MyDelegate(string text);
private MyDelegate d;

protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
    {
        d = new MyDelegate(MyMethod);
    }

    // create connection
    // ...

    // create thread
    if(Session["thread"] == null)
    {
        Session["thread"] = new Thread(new ThreadStart(RunReceiver));
    }

    Thread receiverThread = (Thread)Session["thread"];

    if (!receiverThread.IsAlive)
    {
        receiverThread.Start();
        Debug.WriteLine("Receiver thread started!");
    }
}

/// <summary>
/// receive messages from the server
/// </summary>
private void RunReceiver()
{
    byte[] data = null;

    while (con.GetClient().Connected)
    {
        // if stream contains data to recieve
        if (con.GetStream().DataAvailable)
        {
            Debug.WriteLine("client receiving some data");

            // create new buffer to store received data
            data = new Byte[256];

            // read data from stream
            Int32 bytes = con.GetStream().Read(data, 0, data.Length);

            // convert to readable text
            responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);

            // display message in chat
            d(responseData);
        }

        Thread.Sleep(400);
    }
}

private void MyMethod(string text)
{
    ServerDataArea.Text += text + "\r\n";
}

the Debug.WriteLine(ServerDataArea.Text) does show me what should be visible in the textbox but it is not visible and I just can not figure out how to make it visible..

Answer 1

EDIT : (Removed bunk) Your code is running on a seperate thread from the controls UI thread, and the UI will only allow updates via the controls UI thread.

Try updating the textbox value outside of the new thread you've created.

This is a difficult problem to solve so I suggest you achieve what you want a different way.

Taken from here "Technically, you shouldn't be accessing a control from any other thread except the one it was created on.

Accessing controls from a secondary thread is not guaranteed. It might work sometimes but you shouldn't rely on it.

Instead, you should define a delegate and use the delegate to marshal the calls from the secondary thread to the main thread when accessing your controls. I'm not sure if this would speed up the update but here's how you would update a textbox's text from another thread (VB alert):

EDIT 2 : Converted vb function to C#

public delegate void SetTextDelegate(string sText);

private SetTextDelegate SetText = new SetTextDelegate(SetTextBoxText);

private void SetTextBoxText(string sText)
{
    tbStatus.Text = sText;
}