java - 将 udp 消息从 android 手机发送到 PC(windows)不工作

Question

我想使用 WIFI 连接从我的 android 手机 4.2(客户端)向 PC(服务器)发送 UDP 消息。我的手机和电脑是通过无线路由器连接的。但是从电话到手机没有收到任何消息。我还成功测试了此代码以实现 PC 到 PC 连接。我已将 Internet 权限添加到 manifest.xml。如果你能帮助我，我会很高兴。谢谢你。我已添加此权限。

 <uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> 

客户:

@Override
    protected void onCreate(Bundle savedInstanceState)
    {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);




        Button button1 = (Button) findViewById(R.id.button1);
        final TextView tv = (TextView) findViewById(R.id.textView1);
        final TextView tv2= (TextView) findViewById(R.id.textView2);







        button1.setOnClickListener(new OnClickListener()
        {

            @Override
            public void onClick(View v) 
            {

                boolean morgan= isOnline();
                String s = String.valueOf(morgan);
                tv.setText(s);


                try{

                    //InetAddress ipaddress = InetAddress.getByName("localhost");
                    InetAddress ipaddress = InetAddress.getByName("192.168.10.11");
                    int port = 6500;
                    //byte[] buffer = new byte[1024]; // empty byte array
                    String msg ="hello goooooooogle"; // send this message to the server
                    byte [] b_array = msg.getBytes();

                    //on SERVER side DatagramSocket able to receive packets on 8080 port
                    DatagramPacket packet = new DatagramPacket(b_array, b_array.length, ipaddress, port);// DatagramPacket(byte[], byte_length, InetAddress, port_number)
                    DatagramSocket socket = new DatagramSocket();
                    socket.send(packet);
                    socket.close();

                }
                catch(Exception e)
                {
                    System.out.println(e);
                }
                }




        });   
    }

    public boolean isOnline() {

        Runtime runtime = Runtime.getRuntime();
        try {

            Process ipProcess = runtime.exec("/system/bin/ping -c 1 192.168.10.11");
            //Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
            int     exitValue = ipProcess.waitFor();
            return (exitValue == 0);

        } 
        catch (IOException e)         
        { e.printStackTrace(); } 
          catch (InterruptedException e) { e.printStackTrace(); }

        return false;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item)
    {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings)
        {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

服务器

public class server 
{
    public static void main(String args[])
    {

        try{
            System.out.println("aaa");
            byte[] inbuf = new byte[1000]; // default size
            DatagramPacket packet = new DatagramPacket(inbuf, inbuf.length);

            DatagramSocket socket = new DatagramSocket(6500);
            socket.receive(packet);

            int numBytesReceived = packet.getLength();
            System.out.println(numBytesReceived);
            String s = new String(inbuf);
            System.out.println(s);
            //System.out.println(inbuf[2]);

            socket.close();
        }
        catch(Exception e)
        {
            System.out.println(e);
        }
    }
}

Answer 1

在 Android 上处理网络操作时，建议使用单独的线程来执行此类操作。因此，请尝试将 onClick() 方法中的代码隔离到 AsyncTask 中以在后台运行它。

private class SendMessageTask extends AsyncTask<String, Void, Void> {
 protected Void doInBackground(String... ip) {
     // run network socket code here
     return null;
 }
}

然后 onClick() 将包含如下内容:

new SendMessageTask().execute("IP_HERE");

显然，您可以修改它以满足您的需要。但是，如果您需要在应用程序的生命周期内发送更多数据，您可能需要使用自己的后台线程。这里有一个更详细的解释为什么网络操作不能/不应该在 UI 线程中完成 - http://www.androiddesignpatterns.com/2012/06/app-force-close-honeycomb-ics.html