我做了一个聊天系统,但遇到了这个错误:
Cross-thread operation not valid: 'MessageBox' etc.
我所做的:我添加了一个调用。这是代码:
Invoke(new Action(() => messageBox.Items.Add(usersName.Text + ": " + receivedMessage)));
问题是,它基本上从其他用户发送了一条空白消息。这是因为我在本地连接到聊天。这是一张图片:
接收消息:
private void MessageCallBack(IAsyncResult aResult)
{
try
{
byte[] receivedData = new byte[1500];
receivedData = (byte[])aResult.AsyncState;
ASCIIEncoding aEncoding = new ASCIIEncoding();
string receivedMessage = aEncoding.GetString(receivedData);
Invoke(new Action(() => messageBox.Items.Add(usersName.Text + ": " + receivedMessage)));
buffer = new byte[1500];
socket.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref theirIp, new AsyncCallback(MessageCallBack), buffer);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
发送消息:
private void sendBtn_Click(object sender, EventArgs e)
{
try
{
if (messageTb.Text == "")
{
return;
}
else
{
ASCIIEncoding eEncoding = new ASCIIEncoding();
byte[] msg = new byte[1500];
msg = eEncoding.GetBytes(messageTb.Text);
socket.Send(msg);
messageBox.Items.Add(yourName.Text + ": " + messageTb.Text);
messageTb.Clear();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
this.ActiveControl = messageTb;
}
最佳答案
每当您尝试访问表单主线程之外的不同线程中的控件时,就会发生此异常。
我使用下面的简单日志机制,这只适合简单的应用程序。
private delegate void LogDelegate(ListBox messageBox, string data);
private LogDelegate _logDelegate;
private void Log(ListBox messageBox, string data)
{
if (messageBox.InvokeRequired)
{
LogDelegate logDelegate = Log;
Invoke(logDelegate, messageBox, data);
}
else
{
messageBox.Items.Add(data);
}
}
public Form1()
{
InitializeComponent();
//don't forget, initialize the delegate
_logDelegate = Log;
}
private void btn_Start_Click(object sender, EventArgs e)
{
Log("Anything to log");
}
private void MessageCallBack(IAsyncResult aResult)
{
try
{
//Instead of Invoke use
//Invoke(new Action(() => messageBox.Items.Add(usersName.Text + ": " + receivedMessage)));
Log("Anything to log");
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
正如我所说,该代码可以在任何地方使用并且很简单。但为了更复杂的日志机制和更好的性能,请使用 Log4Net 或 NLog。
关于c# - 使用 Invoke 时跨线程操作无效,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35230729/