2012.6.6文件操作，大文件传输

public Form1()        {            InitializeComponent();            label1.Text = "";            System.Windows.Forms.Control.CheckForIllegalCrossThreadCalls = false;         }        private void btnsel_Click(object sender, EventArgs e)        {            DialogResult dalogresult = openFileDialog1.ShowDialog();            if (DialogResult.OK == dalogresult)            {                txtpath.Text = openFileDialog1.FileName;            }            else            {                txtpath.Text = "";            }            textBox2.Text = Path.Combine(textBox2.Text, Path.GetFileName(txtpath.Text));                   }        Thread th = null;        private void btnstart_Click(object sender, EventArgs e)        {            label1.Text = "";            progressBar1.Visible = true;            progressBar1.Minimum = 0;            progressBar1.Maximum = 10000;            progressBar1.Value = 0;            th = new Thread(new ThreadStart(getth));            th.IsBackground = true;            th.Start();                    }        double getprogressBarint(double sum,double num)        {            double x = sum / 10000;            double barint = 0;            barint = num / x;            return barint;        }               void getth()        {            byte[] b = new byte[1024*1024];            using (FileStream sr = new FileStream(txtpath.Text, FileMode.Open))            {                int i = 0;                double sum = sr.Length;                using (FileStream srr = new FileStream(textBox2.Text, FileMode.OpenOrCreate))                {                    while (sr.Read(b, i, b.Length) != 0)                    {                        srr.Write(b, i, b.Length);                        label1.Text ="已传输"+srr.Length+"个字节/共有" + sum+"字节";                        double getint = getprogressBarint(sum, srr.Length);                        int print= Convert.ToInt16(getint);                        if (print >= progressBar1.Maximum)                        {                            progressBar1.Value = progressBar1.Maximum;                        }                        else                        {                            progressBar1.Value = print;                        }                    }                }            }            progressBar1.Value = progressBar1.Maximum;            th.Abort();        }