大文件Copy

 private void button3_Click(object sender, EventArgs e)

        {

            Thread thread = null;

            //为了不让界面死掉，要将该操作放在一个线程中

            thread = new Thread

                (

                () =>

                {

                    //告诉系统不去检测非法的跨线程调用

                    CheckForIllegalCrossThreadCalls = false;

                    //创建一个文件流指向源文件

                    FileStream fsRead = new FileStream(this.textBox1.Text, FileMode.Open);

                    //创建一个文件流指向目标文件

                    FileStream fsWrite = new FileStream(this.textBox2.Text, FileMode.Create);

                    //记录一下该文件的长度

                    long fileLength = fsRead.Length;

                    //定义一个1M的缓冲区

                    byte[] buffer = new byte[1024 * 1024];

                    //先读取一次,并且将读取到的真正内容长度记录下来

                    int readLength = fsRead.Read(buffer, 0, buffer.Length);

                    //用来记录已经将多少内容写入到了文件中

                    long readCount = 0;

                    //只要读取到的内容不为0就接着读

                    while (readLength!=0)

                    {

                        //将前面已经读取到内存中的数据写入到文件中

                        fsWrite.Write(buffer ,0,readLength);

                        //已经读取的数量累加

                        readCount += readLength;

                        //计算已经读取的数据百分比

                        int percentage =(int)( readCount * 100 / fileLength);

                        this.progressBar1.Value = percentage;

                        //进行下一次读取

                        readLength = fsRead.Read(buffer, 0, buffer.Length);

                    }

                    fsRead.Close();

                    fsWrite.Close();

                    //清空缓冲区

                    buffer = null;

                    //回收一下内存

                    GC.Collect();

                    thread.Abort();

                }

                );

            thread.Start();

        }