大文件Copy 大数据量复制

 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();
        }