winform多线程调用控件

        private void button1_Click(object sender, EventArgs e)
        {
           Thread th= new Thread(delegate()
            {
                for (int i = 0; i < 10; i++)
                {
                    System.Threading.Thread.Sleep(2000);//工作线程不阻塞UI线程
                    DoCreate_test(i);
                }
            });
            th.Start();
            richTextBox1.AppendText("\n" + System.Threading.Thread.CurrentThread.Name + ":" + "UI线程开始" + DateTime.Now);//代码A
            System.Threading.Thread.Sleep(4000);
            richTextBox1.AppendText("\n" + System.Threading.Thread.CurrentThread.Name + ":" + "UI线程结束" + DateTime.Now); //代码B
        }

        private delegate void FlushClient(int i);
        private static int a = 0;
        private void DoCreate_test(int cnt)
        {
            //非ui线程调用委托
            if (richTextBox1.InvokeRequired)
            {
                FlushClient fc = new FlushClient(DoCreate_test);
                this.BeginInvoke(fc,new object[]{cnt});
            }
            //ui线程直接操作
            else
            {
                //System.Threading.Thread.Sleep(2000); //错误写法阻塞UI线程
                richTextBox1.AppendText("\n" + System.Threading.Thread.CurrentThread.Name + ":" +(++a)); //代码C
            }
        }