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C中的安全多线程访问#

windows-forms-designer multithreading c#

droledenom · 技术社区 · 7 年前

我正在尝试实现聊天。我带了密码 here

从除创建它的线程。

其中,ListMessage是随Visual Studio添加的ListView。

       private void buttonSend_Click(object sender, EventArgs e)
        {
            //convert string message to byte[]
            ASCIIEncoding aEncoding = new ASCIIEncoding();
            byte[] sendingMessage = new byte[1500];
            sendingMessage = aEncoding.GetBytes(textMessage.Text);
            //sending the encoded message
            sck.Send(sendingMessage);
            //adding to the list box
            listMessage.Items.Add("Me:" + textMessage.Text);
            textMessage.Text = "";
        }

        private void MessageCallBack(IAsyncResult aResult)
        {
            try
            {
                byte[] receivedData = new byte[1500];
                receivedData = (byte[])aResult.AsyncState;
                //converting byte[] to string
                ASCIIEncoding aEncoding = new ASCIIEncoding();
                string receivedMessage = aEncoding.GetString(receivedData);

                //Adding this message into list box
///// error is given in the following line/////
                listMessage.Items.Add("Friend:" + receivedMessage);

                buffer = new byte[1500];
                sck.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new AsyncCallback(MessageCallBack), buffer);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

here

        private void MessageCallBack(IAsyncResult aResult)
        {
            try
            {
                byte[] receivedData = new byte[1500];
                receivedData = (byte[])aResult.AsyncState;
                //converting byte[] to string
                ASCIIEncoding aEncoding = new ASCIIEncoding();
                string receivedMessage = aEncoding.GetString(receivedData);

                //Adding this message into list box
                //listMessage.Items.Add("Friend:" + receivedMessage);
                listMessage.AddItemSafe("Friend:" + receivedMessage);

                buffer = new byte[1500];
                sck.BeginReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref epRemote, new AsyncCallback(MessageCallBack), buffer);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

        private void AddItemSafe(string text)
        {
            if (this.InvokeRequired)
            {
                AddItemSafeCallback a = new AddItemSafeCallback(AddItemSafe);
                this.Invoke(a, new object[] { text });
            }
            else
            {
                this.Items.Add(text);
            }
        }

        delegate void AddItemSafeCallback(string text);

“ListBox”不包含“AddItemSafe”的定义,也不包含扩展methode。”可以找到AddItemSafe“接受类型为“ListBox”的第一个参数(您是否缺少using指令或程序集引用”
可以找到“ListBox”(您是否缺少using指令或程序集引用'

你认为我试图解决最初问题的方法是好的吗
如果是,我尝试的解决方案有什么问题

1 回复 | 直到 7 年前

Akos Nagy 7 年前

是的,这种方法非常正确,但在实现过程中确实遗漏了一些东西。

AddItemSafe 方法只是窗体子类中的一个方法,而不是 listMessage (无论是哪种类型)。所以当你调用它时,你只需要指定方法名和参数,而不需要在另一个对象实例上调用它。

...
ASCIIEncoding aEncoding = new ASCIIEncoding();
string receivedMessage = aEncoding.GetString(receivedData);
//Adding this message into list box
//listMessage.Items.Add("Friend:" + receivedMessage);

// !!!!Note difference here:
AddItemSafe("Friend:" + receivedMessage);
...

然后,在AddItemSafe方法中,您可以完全像在单线程环境中一样执行操作,即添加到 列表消息

private void AddItemSafe(string text)
{
  if (this.InvokeRequired)
  {
    AddItemSafeCallback a = new AddItemSafeCallback(AddItemSafe);
    this.Invoke(a, new object[] { text });
  }
  else
  {
    // !!!!Note difference here:
    listmessage.Items.Add(text);
  }
}