java - android tcp/ip 套接字不会将数据发送到计算机

Question

我试图制作一个应用程序，将数据从 android 发送到计算机(java 到 vb.net)。数据发送在 eclipse java 项目中有效，但在 android 项目中无效。但我有一个问题。我的计算机中没有传入数据到 Visual Basic。VB代码:

 Imports System.Net.Sockets
 Imports System.Threading
 Imports System.IO

Public Class Form1

Dim Listener As New TcpListener(65535)
Dim Client As New TcpClient
Dim Message As String = ""

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim ListThread As New Thread(New ThreadStart(AddressOf Listening))
    ListThread.Start()
End Sub

Private Sub Listening()
    Listener.Start()
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

    Client = New TcpClient("192.168.100.3", 65535)

    Dim Writer As New StreamWriter(Client.GetStream())
    Writer.Write(TextBox2.Text)
    Writer.Flush()
End Sub

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    If Listener.Pending = True Then
        Message = ""
        Client = Listener.AcceptTcpClient()

        Dim Reader As New StreamReader(Client.GetStream())
        While Reader.Peek > -1
            Message = Message + Convert.ToChar(Reader.Read()).ToString
        End While

        MsgBox(Message, MsgBoxStyle.OkOnly)
    End If
 End Sub

Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As     System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
    Listener.Stop()
End Sub

End Class

java代码:

package com.example.androidclient2;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.Socket;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {
TextView serverMessage;
Thread m_objThreadClient;
Socket clientSocket;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    serverMessage=(TextView)findViewById(R.id.textView1);
}
public void Start(View view)
{
m_objThreadClient=new Thread(new Runnable() {
      public void run()
       {
          try 
           {
             clientSocket= new Socket("192.168.100.3",65535);
             ObjectOutputStream oos = new ObjectOutputStream(clientSocket.getOutputStream());
             oos.writeObject("Hellow there");
             Message serverMessage= Message.obtain();
             ObjectInputStream ois =new     ObjectInputStream(clientSocket.getInputStream());
             String strMessage = (String)ois.readObject();
            serverMessage.obj=strMessage;
            mHandler.sendMessage(serverMessage); 
            oos.close();
            ois.close();
           } 
           catch (Exception e) 
           {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

         }
        });

 m_objThreadClient.start();

}
Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
    messageDisplay(msg.obj.toString());
}
};
public void messageDisplay(String servermessage)
{
serverMessage.setText(""+servermessage);
}

}

感谢您的帮助。

Answer 1

今天刚刚在 android 上创建并测试了这个类:

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import android.content.Context;
import android.os.AsyncTask;
import android.os.Handler;
import android.util.Log;
import android.widget.Toast;

public class TcpClient {

private static final String TAG = TcpClient.class.getSimpleName();

private Socket socket;
private PrintWriter out;
private boolean connected;

public TcpClient()
{
    socket = null;
    out = null;
    connected = false;
}


public void connect(Context context, String host, int port)
{
    new ConnectTask(context).execute(host, String.valueOf(port));
}

private class ConnectTask extends AsyncTask<String, Void, Void> {

    private Context context;

    public ConnectTask(Context context) {
        this.context = context;
    }

    @Override
    protected void onPreExecute() {
        showToast(context, "Connecting..");
        super.onPreExecute();
    }

    @Override
    protected void onPostExecute(Void result) {
        if (connected) {
            showToast(context, "Connection successfull");
        }           
        super.onPostExecute(result);
    }

    private String host;
    private int port;

    @Override
    protected Void doInBackground(String... params) {
        try {
            String host = params[0];
            int port = Integer.parseInt(params[1]);
            socket = new Socket(host, port);
            out = new PrintWriter(socket.getOutputStream(), true);
        } catch (UnknownHostException e) {
            showToast(context, "Don't know about host: " + host + ":" + port);
            Log.e(TAG, e.getMessage());
        } catch (IOException e) {
            showToast(context, "Couldn't get I/O for the connection to: " + host + ":" + port);
            Log.e(TAG, e.getMessage());
        }
        connected = true;
        return null;
    }


}

public void disconnect(Context context)
{
    if ( connected )
    {
        try {
            out.close();
            socket.close();
            connected = false;
        } catch (IOException e) {
            showToast(context, "Couldn't get I/O for the connection");
            Log.e(TAG, e.getMessage());
        }            
    }
}


/**
 * Send command to a Pure Data audio engine. 
 */
public void send(String command)
{
    if ( connected ) out.println(command +";");   
}

private void showToast(final Context context, final String message) {
    new Handler(context.getMainLooper()).post(new Runnable() {

        @Override
        public void run() {
            Toast.makeText(context, message, Toast.LENGTH_LONG).show();
        }
    });
}
}

即使我在您的代码中没有看到明显的错误，它也可能对您有所帮助。

该设备是否与您的计算机位于同一个 WiFi 网络中？例如，它无法通过 USB 工作。