java - 我发现我的代码在 "socket socket = serverSocket.accept();"之后没有跟随，程序卡在这里

Question

图片:

Please view screenshot

我正在尝试在 android 模拟器中进行套接字编程，在两个不同的模拟器上运行客户端和服务器。我发现我的代码在“socket socket = serverSocket.accept();”之后没有跟随，程序卡在这里。我正在使用 ip : 10.0.2.2 作为其他 ip 给出 I/O 异常。另外，我知道 serverSocket.accept() 的作用，我的问题是我无法解决该问题。为什么它总是在等待客户端，即使我的客户端正在尝试连接它。请检查我的服务器和客户端代码，让我知道是否有人可以解决这个问题。

服务器:

package com.example.serverside;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.Enumeration;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    TextView info, infoip, msg;
    String message = "";
    ServerSocket serverSocket;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        info = (TextView) findViewById(R.id.info);
        infoip = (TextView) findViewById(R.id.infoip);
        msg = (TextView) findViewById(R.id.msg);

        infoip.setText(getIpAddress());

        Thread socketServerThread = new Thread(new SocketServerThread());
        socketServerThread.start();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        if (serverSocket != null) {
            try {
                serverSocket.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    private class SocketServerThread extends Thread {

        static final int SocketServerPORT = 8080;
        int count = 0;

        @Override
        public void run() {
            try {
                serverSocket = new ServerSocket(SocketServerPORT);
                MainActivity.this.runOnUiThread(new Runnable() {

                    @Override
                    public void run() {
                        info.setText("I'm waiting here: "
                                + serverSocket.getLocalPort());
                    }
                });

                while (true) {
                    Socket socket = serverSocket.accept();
                    count++;
                    message += "#" + count + " from " + socket.getInetAddress()
                            + ":" + socket.getPort() + "\n";

                    MainActivity.this.runOnUiThread(new Runnable() {

                        @Override
                        public void run() {
                            msg.setText(message);
                        }
                    });

                    SocketServerReplyThread socketServerReplyThread = new SocketServerReplyThread(
                            socket, count);
                    socketServerReplyThread.run();

                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

    private class SocketServerReplyThread extends Thread {

        private Socket hostThreadSocket;
        int cnt;

        SocketServerReplyThread(Socket socket, int c) {
            hostThreadSocket = socket;
            cnt = c;
        }

        @Override
        public void run() {
            OutputStream outputStream;
            String msgReply = "Hello from Android, you are #" + cnt;

            try {
                outputStream = hostThreadSocket.getOutputStream();
                PrintStream printStream = new PrintStream(outputStream);
                printStream.print(msgReply);
                printStream.close();

                message += "replayed: " + msgReply + "\n";

                MainActivity.this.runOnUiThread(new Runnable() {

                    @Override
                    public void run() {
                        msg.setText(message);
                    }
                });

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                message += "Something wrong! " + e.toString() + "\n";
            }

            MainActivity.this.runOnUiThread(new Runnable() {

                @Override
                public void run() {
                    msg.setText(message);
                }
            });
        }

    }

    private String getIpAddress() {
        String ip = "";
        try {
            Enumeration<NetworkInterface> enumNetworkInterfaces = NetworkInterface
                    .getNetworkInterfaces();
            while (enumNetworkInterfaces.hasMoreElements()) {
                NetworkInterface networkInterface = enumNetworkInterfaces
                        .nextElement();
                Enumeration<InetAddress> enumInetAddress = networkInterface
                        .getInetAddresses();
                while (enumInetAddress.hasMoreElements()) {
                    InetAddress inetAddress = enumInetAddress.nextElement();

                    if (inetAddress.isSiteLocalAddress()) {
                        ip += "SiteLocalAddress: "
                                + inetAddress.getHostAddress() + "\n";
                    }

                }

            }

        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            ip += "Something Wrong! " + e.toString() + "\n";
        }

        return ip;
    }
}

客户:

package com.example.clientside;

import android.os.Bundle;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
import java.net.UnknownHostException;
import android.os.AsyncTask;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.BufferedInputStream;

public class MainActivity extends Activity {

    TextView textResponse;
    EditText editTextAddress, editTextPort;
    Button buttonConnect, buttonClear;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editTextAddress = (EditText)findViewById(R.id.address);
        editTextPort = (EditText)findViewById(R.id.port);
        buttonConnect = (Button)findViewById(R.id.connect);
        buttonClear = (Button)findViewById(R.id.clear);
        textResponse = (TextView)findViewById(R.id.response);

        buttonConnect.setOnClickListener(buttonConnectOnClickListener);

        buttonClear.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                textResponse.setText("");
            }});
    }

    OnClickListener buttonConnectOnClickListener =
            new OnClickListener(){

                @Override
                public void onClick(View arg0) {
                    MyClientTask myClientTask = new MyClientTask(
                            editTextAddress.getText().toString(),
                            Integer.parseInt(editTextPort.getText().toString()));
                    myClientTask.execute();
                }};

    public class MyClientTask extends AsyncTask<Void, Void, Void> {

        String dstAddress;
        int dstPort;
        String response = "";

        MyClientTask(String addr, int port){
            dstAddress = addr;
            dstPort = port;
        }

        @Override
        protected Void doInBackground(Void... arg0) {

            Socket socket = null;

            try {
                socket = new Socket(dstAddress, dstPort);

                ByteArrayOutputStream byteArrayOutputStream =
                        new ByteArrayOutputStream(1024);
                byte[] buffer = new byte[1024];

                int bytesRead;
                InputStream inputStream = socket.getInputStream();

                /*
                 * notice:
                 * inputStream.read() will block if no data return
                 */
                while ((bytesRead = inputStream.read(buffer)) != -1){
                    byteArrayOutputStream.write(buffer, 0, bytesRead);
                    response += byteArrayOutputStream.toString("UTF-8");
                }

            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                response = "UnknownHostException: " + e.toString();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                response = "IOException: " + e.toString();
            }finally{
                if(socket != null){
                 try {
                        socket.close();
                   } catch (IOException e) {
                       // TODO Auto-generated catch block
                       e.printStackTrace();
                   }
                }
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            textResponse.setText(response);
            super.onPostExecute(result);
        }

    }

}

Answer 1

实际上并没有卡住......当您的客户端连接时，将执行进一步的代码

在服务器代码中从此代码获取IP地址

public static String getLocalIpAddress() {
        try {
            for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements(); ) {
                NetworkInterface intf = en.nextElement();

                for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements(); ) {
                    InetAddress inetAddress = enumIpAddr.nextElement();
                    if (!inetAddress.isLoopbackAddress() && inetAddress instanceof Inet4Address) {
                        return inetAddress.getHostAddress();
                    }
                }
            }
        } catch (Exception ex) {
            Log.e("IP Address", ex.toString());
        }
        return null;
    }

当您获得 IP 地址后，尝试使用此 IP 和端口 8080 进行连接