高級打字工!!!

 private void button8_Click(object sender, EventArgs e)
        {
            //取得目前執行緒ID
            MessageBox.Show(Thread.CurrentThread.ManagedThreadId.ToString());

            //透過非同步方法取得主機
            Dns.BeginGetHostAddresses(this.textBox1.Text, new AsyncCallback(getAddressList), null);

        }

        private void getAddressList(IAsyncResult iar)
        {
            string str = "";
            if (iar.IsCompleted)
            {
                //解析主機名稱
                IPHostEntry iphe = Dns.Resolve(this.textBox1.Text);
                foreach (IPAddress ipa in iphe.AddressList)
                {
                    str += ipa + Environment.NewLine + " = " + Thread.CurrentThread.ManagedThreadId;
                }
            }
            this.setText(str);
        }

        //委派物件傳入參數型態須與指定之方法的傳入參數相同型態
        private delegate void AddIPCallback(string str);

        private void setText(string str)
        {
            //確認建立控制項的執行緒與目前執行緒是否相同,不同則True,反之
            if (this.textBox2.InvokeRequired)
            {
                //傳入委派物件,第二參數為setText的傳入參數
                this.textBox2.Invoke(new AddIPCallback(setText), str + " = " + Thread.CurrentThread.ManagedThreadId);
            }
            else
            {
                this.textBox2.Text = str + " = " + Thread.CurrentThread.ManagedThreadId;
            }
        }

參考:https://sites.google.com/site/hydrothecs/library-1/crossthread