WebService 大文件断点续传

        /// <summary>
        /// 服务端: 
        /// </summary>
        /// <param name="FileName">更新文件包名</param>
        /// <param name="Offset">偏移</param>
        /// <param name="Count">每次读取字节数 单位KB</param>
        /// <returns>字节组</returns>
        [WebMethod(Description = "<b>大文件下载</b> 测试")]
        public byte[] getFile(string FileName, long Offset, int Count)
        {
            //指定下载文件夹+文件名
            string strPath = @"E:\\" + FileName;

            if (Offset < 0) { Offset = 0; }

            byte[] btBuf = new byte[Count];

            if (System.IO.File.Exists(strPath))
            {
                System.IO.FileStream fs = new System.IO.FileStream(strPath, System.IO.FileMode.Open);
                if (Offset < fs.Length)
                {
                    if (0 < (int)(fs.Length - Offset) && (int)(fs.Length - Offset) < Count)
                    {
                        Count = (int)(fs.Length - Offset);
                    }
                    btBuf=new byte[Count];

                    fs.Seek(Offset, System.IO.SeekOrigin.Begin);
                    fs.Read(btBuf, 0, Count);
                }
                else
                { btBuf = null; }
                fs.Flush();
                fs.Close();
                fs.Dispose();               
            }
            return btBuf;
        }

//--------------------------------客户端调用:

 

 private string DownLoadPath(string strClientFilePath, string fileName)
    {
        string result = "DownLoading...";

        ws1.Service s1 = new ws1.Service(); 

        //本地数据
        System.IO.FileStream ns;

        //文件保存路径
        string strPath = strClientFilePath + @"\" + fileName;

        //源文件名
        string serverFileName = @"Enterprise.msi";

        //传输数据长度,每次取字节组大小
        int count = 1024 * 100;
       
        //申请内存，存放取回的数据
        byte[] buffer = new byte[count];

        //文件偏移
        long offset = 0;

        //取回数据字节长度
        int bufferSize = 1;

        //-------------
        while (bufferSize > 0)
        {
           
            //读取本地文件信息
            ns = new System.IO.FileStream(strPath, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.ReadWrite);
           
            //获取本地数据长度，设定从服务器取数据偏移指针位置
            offset = ns.Length;

            //取服务端数据
            buffer = s1.getFile(serverFileName, offset, count);
            if (buffer!=null)
            {
                ns.Seek(offset, System.IO.SeekOrigin.Begin);
                count = buffer.Length;
                ns.Write(buffer, 0, count);
            }
            else
            {
                bufferSize = -1;
                result = "Successful !";
            }
            ns.Flush();
            ns.Close();
            ns.Dispose();
        }
        return result;       
    }