java - 在Java/Android中使用套接字多次发送二进制数据

Question

我需要在Android设备上使用Java套接字多次发送二进制数据。
这是一个简单的对象，可导出run()和send()方法。

public class GpcSocket {

    private Socket socket;

    private static final int SERVERPORT = 9999;
    private static final String SERVER_IP = "10.0.1.4";

    public void run() {
        new Thread(new ClientThread()).start();
    }

    public int send(byte[] str) {
        try {
            final BufferedOutputStream outStream = new BufferedOutputStream(socket.getOutputStream());
            outStream.write(str);
            outStream.flush();
            outStream.close();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return str.length;
    }

    class ClientThread implements Runnable {
        @Override
        public void run() {
            try {
                InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
                socket = new Socket(serverAddr, SERVERPORT);
            } catch (UnknownHostException e1) {
                e1.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }
}

对于Android编程，我使用Scaloid，这是多次发送二进制数据的代码。 count由参数给出。 result是Byte [Array]类型的数据，并且gpc在onCreate()方法中初始化为gpc = new GpcSocket()。

gpc.run()
for (i <- 1 to count) {
  val length = gpc.send(result)
  toast(s"Sent: $i $length")
}

问题是，即使我尝试多次发送数据，接收方也只能接收到一个数据包。这是我发送信息5次时在服务器(接收方)端显示的内容:

55:2015-03-21 03:46:51 86: <RECEIVED DATA>
10.0.1.27 wrote:
56:2015-03-21 03:46:51 0:
10.0.1.27 wrote:
57:2015-03-21 03:46:51 0:
10.0.1.27 wrote:
58:2015-03-21 03:46:51 0:
10.0.1.27 wrote:
59:2015-03-21 03:46:51 0:

我的问题是

这是为什么？为什么接收器只接收一次？发件人表明已发送信息五次。

是否需要在发送多次之前只使用一次run()？或者，每当我使用send()时都必须调用run()吗？

这是Python中的服务器端代码:

import SocketServer
from time import gmtime, strftime

count = 1

class MyTCPHandler(SocketServer.BaseRequestHandler):
    """
    The RequestHandler class for our server.

    It is instantiated once per connection to the server, and must
    override the handle() method to implement communication to the
    client.
    """

    def handle(self):
        # self.request is the TCP socket connected to the client
        self.data = self.request.recv(1024).strip()
        print "{} wrote:".format(self.client_address[0])
        global count
        count += 1
        print "%d:%s %d:%s" % (count, strftime("%Y-%m-%d %H:%M:%S", gmtime()), len(self.data), self.data)
        # just send back the same data, but upper-cased
        self.request.sendall(self.data.upper())

if __name__ == "__main__":
    HOST, PORT = "10.0.1.4", 9999

    # Create the server, binding to localhost on port 9999
    server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)

    # Activate the server; this will keep running until you
    # interrupt the program with Ctrl-C
    server.serve_forever()

Answer 1

从这篇文章:Sending ByteArray using Java Sockets (Android programming)和How to fix java.net.SocketException: Broken pipe?，似乎send()方法是错误的。

使用完资源后，请关闭它们

我将send()修改为创建套接字并在使用完毕后将其关闭的方法很简单。

public int send(byte[] str) throws IOException {
    InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
    socket = new Socket(serverAddr, SERVERPORT);
    out = socket.getOutputStream();
    out.write(str);
    out.flush();
    out.close();
    socket.close();
    return str.length;
}

修改调用者代码

调用它的scala代码被修改为调用send()方法。

// gpc.run()
for (i <- 1 to count) {
  ...
  val length = gpc.send(result)
  println(s"Sent: $i $length")
}

... in initializer
gpc = new GpcSocket()

在Android中更改政策模式

提示:android.os.NetworkOnMainThreadException at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)，应为Android设备添加此代码，以防止E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: scaloid.example, PID: 1791 android.os.NetworkOnMainThreadException错误。

val policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);