异步下载byte[]问题，在线等，搞定立即结贴，急急急急急急急

Question

byte[] allbuf=null
private void ReceiveCallBack(IAsyncResult ar)
{
  allbuf   //2M缓存
  filebuf  //文件字节数组，这时数据已经写如filebuf
  Array.Copy(allbuf);//简化了写发，我只是想表达意思，这里把文件字节复制到2M缓存
  allbuf=new byte[Array.Length]
  if (token[1] == allbuf.Length.ToString() || allbuf.Length == (2048 *1024) || j==bagnum || allbuf.Length > 2096640)
  {
    写如硬盘
  }
  BeginReceive(.......); //接收文件 
}

Answer 1

这样不行，Array.Copy(allbuf);这里会报错的，因为allbuf不能为空
我这里的具体写发为         //要被复制的参数，被复制的开始索引，目标，目标索引，复制数目
Array.Copy(cs.buff, receivebuf.Length, allbuf, i, cs.buff.Length - receivebuf.Length);
如果在前面allbuf=null,这里复制时就会报错

Answer 2

如果有耐心的人可以看下我的接收源码  谢谢，这样具体些
 private void ReceiveCallBack(IAsyncResult ar)
        {
            try
            {
                Client cs = (Client)ar.AsyncState;
                int len = ConnSocket.EndReceive(ar);//这个地方的socket有问题，要考虑
                if (len != 0)
                {
                    string msg = System.Text.Encoding.Default.GetString(cs.buff,0,len);
                    string[] token = msg.Split('|');
                    string filepath = @"D:\我是接收的文件.exe";
                    if (token[0] == ((int)cmdd.OK).ToString())
                    {
                        FileStream fs = new FileStream(filepath, FileMode.Append, FileAccess.Write);
                        string cmd = token[0] + "|" + token[1] + "|";
                        string strok = token[0] + "|";
                        byte[] receivebuf = System.Text.Encoding.Default.GetBytes(cmd.ToCharArray());
                        //int baglen=receivebuf.Length + 512*1024;//这是一个包的大小，这里暂时不需要
                        //发送的时候2M的缓冲区只剩下不到512K的容量了，这时我下面是不会写入数据的，但是又发来一个数据包，缓冲区溢出(再写入地方已经解决此问题)
                        //2048*1024/cs.buff.Length
                        Array.Copy(cs.buff, receivebuf.Length, allbuf, i, cs.buff.Length - receivebuf.Length);
                        allbuf = new byte[allbuf.Length];
                        i += cs.buff.Length - receivebuf.Length;
                        bagnum = Convert.ToInt32(token[1]) / (512*1024);//这个地方应该是 （文件+命令*包数）/（命令+512*1024），但是经过数学公式成此代码
                        if (Convert.ToInt32(token[1]) % (512*1024) != 0)
                        {
                            bagnum += 1;
                        }
                        // 当一个文件小与或等于2M时 || 当接收缓冲区allbuf满时 || 当最后一个包发送过来时 || 发送的时候2M的缓冲区只剩下不到512K的容量了，这时是不会写入数据的，但是又发来一个数据包，缓冲区溢出
                        if (token[1] == allbuf.Length.ToString() || allbuf.Length == (2048 * 1024) || j==bagnum || allbuf.Length > 2096640)
                        {                            receivefileDone.Reset();
                            fs.BeginWrite(allbuf,0, allbuf.Length, new AsyncCallback(writefileCallback), fs);
                            receivefileDone.WaitOne();
                            j++;
                            i = 0;
                        }
                        //fs.BeginWrite(cs.buff, receivebuf.Length, len - receivebuf.Length, new AsyncCallback(writefileCallback), fs);
                        if (Convert.ToInt32(token[1]) != fs.Length)//当传过来的文件长度不等于我硬盘文件长度就是没传完，发送OK让服务器继续传
                        {
                            SendToUpServer(cs.ClientSocket, strok);
                        }
                        fs.Flush();
                        int cc=cs.buff.Length;
                        fs.Close();
                    }
                    else if (token[0] == ((int)cmdd.ERR).ToString())
                    {
                        cs.ClientSocket.Close();
                    }
                }
                cs.ClientSocket.BeginReceive(cs.buff, 0, cs.buff.Length, SocketFlags.None, new AsyncCallback(ReceiveCallBack), cs);
            }
            catch (SocketException ex)
            {
                if (ex.ErrorCode == 10054)
                {
                    ConnSocket.Close();
                }
            }
            catch (ObjectDisposedException)
            { }
        }