Java和.NET下socket转换错误记录

Posted 2020-07-31 默默地

一个项目，需要JAVA的Socket客户端转换为C#的Socket客户端，使用的是短连接。

首先，java客户端代码如下：

Socket socket = new Socket();

socket.connect(new InetSocketAddress(ip, port), timeout);

socket.setSoTimeout(respTimeout);

OutputStream outputStream = null;

InputStream is = null;

outputStream = socket.getOutputStream();

...

byte[] allBty = new byte[byteCount];

outputStream.write(allBty);

outputStream.flush();

is = socket.getInputStream();

byte[] bb = new byte[4];

is.read(bb, 0, 4);

...

一开始转换C#代码使用最简单的同步方式，对应代码差异如下：

Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

socket.Connect(new IPEndPoint(IPAddress.Parse(ip), port));

socket.ReceiveTimeout = respTimeout;

...

socket.Send(allBty);

//接收返回的字节流

byte[] buffer = new byte[1024];

int bytesRec = 0;

MemoryStream memStream = new MemoryStream();

while ((bytesRec = socket.Receive(buffer)) >0)//结果第一次Receive接收消息正确，第二次接收就报错：由于连接方在一段时间后没有正确答复或连接的主机没有反应，连接尝试失败。去掉while循环，不会报错，但即使数据量未超过1024，服务端接收并返回了消息，客户端的接收也很不稳定，有时能收到有时收不到；如果超过1024，数据接收不全

{

bytesRec = socket.Receive(buffer);

memStream.Write(buffer, 0, bytesRec);

}

byte[] bb = new byte[4];

memStream .Read(bb, 0, 4);

...

分析：java采取流的方式进行读取，可能是java一次性发送后断开了socket，导致C#不能多次接收，尝试C#也以流的方式接收。

TcpClient tcpClient = new TcpClient();

tcpClient.Connect(IPAddress.Parse(ip), port);

tcpClient.ReceiveTimeout = respTimeout;

NetworkStream sendSteam = null;

NetworkStream receiveSteam = null;

...

sendSteam = tcpClient.GetStream();

sendSteam.Write(allBty, 0, allBty.Length);

sendSteam.Flush();

receiveSteam = tcpClient.GetStream();

bb = new byte[4];

receiveSteam.Read(bb, 0, 4);

...

经测试，通信正常稳定。