private delegate void PicImage();
   Thread th1;
   private void btn_Start1_Click(object sender, EventArgs e)
        {
            th1 = new Thread(new ThreadStart(StartTh1));
            th1.Start();
            ShowData();//费时的代码
        }
        public void StartTh1()
        {
            BeginInvoke(new PicImage(ShowImge));
        }
        public void ShowImge()
        {
            Bitmap bmp = new Bitmap(@"F:\WorkSpace\DONET\ForeignTrader\ForeignTrader\imgs\run.gif",true);
            this.pictureBox1.Image = bmp;
            this.pictureBox1.Refresh();
            this.pictureBox1.Visible = true;
        }
        public void ShowData()//费时的代码
        {
           
            string url = this.tb_url1.Text.Trim();

            if (url.IndexOf(Uri.SchemeDelimiter) < 0)
            {
                url = string.Format("{0}{1}{2}",Uri.UriSchemeHttp,Uri.SchemeDelimiter,url);
            }
            string x = GetHtml(url);
          
              if (x.Contains("CSDN"))
                     MessageBox.Show("true");
                 else
                    MessageBox.Show("false");
                 this.pictureBox1.Visible = false;
     
        }