多线程分块写入文件

 一：分块写入文件

   public static void GetDownLoad()
        {
            var url = @"C:UsersyouzikuDesktopASP.NET+MVC+4框架揭秘(蒋金楠).pdf";
            var path = @"C:UsersyouzikuDesktoppdfmvc.pdf";


            using (Stream s = new FileStream(url, FileMode.Open))
            {
                using (Stream sm = new FileStream(path, FileMode.Create))
                {
                    //数据长度
                    var fileLength = s.Length;
                    //数组长度
                    var partSize = 1024 * 1024;
                    //计算循环次数
                    long count = GetCount(fileLength, partSize);
                    for (int i = 0; i < count; i++)
                    {
                        var start = partSize * i;
                        //剩余长度
                        var sxLength = fileLength - start;
                        //建立一个标准长度的byte数组
                        byte[] bt = new byte[partSize];
                        if (sxLength > partSize)
                        {
                            //向数组中读取数据
                            s.Read(bt, 0, partSize);
                        }
                        else
                        {
                            //剩余长度不够时，重新建立一个byte数组
                            bt = new byte[sxLength];
                            s.Read(bt, 0, Convert.ToInt32(sxLength));
                        }
                        //写入
                        sm.Write(bt, 0, bt.Length);
                    }
                    sm.Flush();
                    sm.Close();
                }
            }
            Console.WriteLine("执行完成");
        }

二：多线程分块写入文件

        //获取文件流
        public void GetDown()
        {
            var url = @"D:office办公cn_office_professional_plus_2013_x64_dvd_1134006.iso";
            Stream rs = new FileStream(url, FileMode.Open);
            //平均每次写入的量
            PartSizeNormal = rs.Length / 10;
            //最后一次把全部数据都写入
            if (rs.Length % 10 != 0)
            {
                PartSizeLast = rs.Length - PartSizeNormal * 9;
            }
            //线程池
            for (int i = 0; i < 10; i++)
            {
                ThreadPool.QueueUserWorkItem(new WaitCallback(WriteFile), rs);
            }

        }

        //创建写入文件
        Stream st = new FileStream(@"C:UsersyouzikuDesktoppdfoffice.iso", FileMode.Create);
       
        //写入文件
        public void WriteFile(object o)
        {
            Stream s = o as Stream;
            Interlocked.Add(ref ck, 1);
            byte[] by = new byte[PartSizeNormal];
            //最后一次写入
            if (ck == 10)
            {
                by = new byte[PartSizeLast];
            }
            s.Read(by, 0, by.Length);
            st.Write(by, 0, by.Length);
            st.Flush();

        }