java - 为什么这段代码会以 "Socket setup caught IOexception"循环

Question

我正在尝试对 Android 服务器/客户端软件集进行故障排除，该软件似乎正在记录大量包含“套接字设置捕获 IO 异常”的 logcat 消息，因此我猜测它处于循环中。为了进行故障排除，我将服务器和客户端安装在同一物理设备上，并遇到了相同的问题。阅读代码我无法弄清楚为什么会这样，我添加了从//STACKEXCHANGE 开始的注释，我在其中看到了三个 logcat 消息被记录。谁能给我一些指示，我不是一个java程序员，只是一个热心的技术人员试图让这个工作......

logcat 按以下顺序记录消息

ControlLoop 启动套接字设置捕获 IOException套接字已建立套接字关闭控制循环结束

这是客户端软件的代码。

    package com.jrbowling.robotclient;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.util.Log; 
import android.widget.ToggleButton;
import android.widget.SeekBar;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.Toast;
import android.widget.EditText;
import android.widget.ImageView;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.view.Window;
import android.view.WindowManager;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException; 
import java.net.SocketTimeoutException;
import android.net.wifi.WifiManager;
import android.net.wifi.WifiManager.WifiLock;
import android.net.wifi.WifiInfo;  
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.view.View.OnTouchListener;
import android.view.MotionEvent;
import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException; 
import java.net.SocketTimeoutException;
import android.app.AlertDialog;
import android.content.DialogInterface;
import java.net.SocketAddress;
import java.net.InetSocketAddress;
import android.os.Handler;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;

public class MainActivity extends Activity {

    Thread vidThread = null;
    Thread clientThread = null;
    private Socket s;

    private static final String TAG = "RobotClient";
    //private ToggleButton tb;
    private ImageButton forward_button;
    private ImageButton reverse_button;
    private ImageButton right_button;
    private ImageButton left_button;
    private SeekBar throttle;

    private ImageView imageWindow;
    private ImageView connectedLED;
    private ImageView signalStrengthIndicator;

    private Boolean stayConnected = false;
    String vidURL = "";
    private String robotIP = "";
    String direction = "stop";
    Integer speed = 100;
    Boolean robotEnabled = true;
    Boolean robotConnected = false;
    private Handler GUIUpdateHandler = new Handler();
    private Integer signalStrength = 0;
    private SharedPreferences pref; 
    private long timeLastPress = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //set fullscreeen, black
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_main);
        setActivityBackgroundColor(0xff000000);

        Log.i(TAG, "Robot client started"); 

        initGUIComponents();

        //get Robot IP from user, kick off threads and GUI updater
        showIPAlert();  

    }

@Override
 protected void onDestroy() {

     Log.d(TAG,"onDestroy() called");
     stayConnected = false;
     socketCleanup();
     super.onDestroy(); 

    }

//@Override
//protected void onPause() {

//   Log.d(TAG,"onPause() called");
//   stayConnected = false;
//   socketCleanup();
//   super.onDestroy();
//   }

@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 void onBackPressed() {
        //on back button, prompt user to press it again within 2 seconds to exit
        Toast onBackPressedToast = Toast.makeText(this, "Press again within 2 seconds to confirm exit", Toast.LENGTH_SHORT);
        long currentTime = System.currentTimeMillis();
        if (currentTime - timeLastPress > 2000) {
            onBackPressedToast.show();
            timeLastPress = currentTime;
        } else {
            onBackPressedToast.cancel();  
            super.onBackPressed();           
        }
    }

 private void initGUIComponents()
    {
        imageWindow = (ImageView) findViewById(R.id.imageView1);
        connectedLED = (ImageView) findViewById(R.id.imageViewConnectStatus);
        signalStrengthIndicator  = (ImageView) findViewById(R.id.ImageViewSignalStrength);
        forward_button = (ImageButton) findViewById(R.id.forwardButton);
        reverse_button = (ImageButton) findViewById(R.id.reverseButton);
        right_button = (ImageButton) findViewById(R.id.rightButton);
        left_button = (ImageButton) findViewById(R.id.leftButton);
        throttle = (SeekBar)findViewById(R.id.throttleSeekbar);
        throttle.setProgress(75); 
        forward_button.setOnTouchListener(forwardButtonListener);
        reverse_button.setOnTouchListener(reverseButtonListener);
        right_button.setOnTouchListener(rightButtonListener);
        left_button.setOnTouchListener(leftButtonListener);
    }

    private void showIPAlert() {

        AlertDialog.Builder alert = new AlertDialog.Builder(this);

        alert.setTitle("Please enter robot IP address");
        alert.setMessage("Example: 192.168.1.100");

        final EditText input = new EditText(this);
        alert.setView(input);
        input.setText(loadIP().toString());

        alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
            robotIP = input.getText().toString();
            Log.i(TAG, "User entered IP " + robotIP);
            saveIP(robotIP);
            //Handler launches GUIUpdater every 1000 ms. Launch when user clicks ok.
            updateGUI();

            //start network thread
            stayConnected = true;

            //launch network thread
            clientThread = new Thread(new ClientThread());
            clientThread.start();

            vidURL = "http://"+robotIP+":8082/shot.jpg";
            vidLoop();
          }
        });

        alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int whichButton) {
              appExit();
          }

        });

        alert.show();   
    }

 private void appExit() 
 {
     Log.i(TAG, "Exit requested by user");
     this.finish();  
 }

 private OnTouchListener forwardButtonListener = new OnTouchListener(){
        public boolean onTouch(View v, MotionEvent event) {
           switch ( event.getAction() ) {
            case MotionEvent.ACTION_DOWN: 
                //setActivityBackgroundColor(0xffff0000);
                direction = "forward";
                 break;
            case MotionEvent.ACTION_UP: 
                //setActivityBackgroundColor(0xff000000);
                direction = "stop";
                 break;
            }
           return false;
        }  
   };

 private OnTouchListener reverseButtonListener = new OnTouchListener(){
       public boolean onTouch(View v, MotionEvent event) {
          switch ( event.getAction() ) {
           case MotionEvent.ACTION_DOWN: 
            //setActivityBackgroundColor(0xffff0000);
            direction = "reverse";
             break;
           case MotionEvent.ACTION_UP: 
            //setActivityBackgroundColor(0xff000000);
            direction = "stop";
             break;
           }
          return false;
       }  
  };

 private OnTouchListener rightButtonListener = new OnTouchListener(){
      public boolean onTouch(View v, MotionEvent event) {
         switch ( event.getAction() ) {
          case MotionEvent.ACTION_DOWN: 
            //setActivityBackgroundColor(0xffff0000);
            direction = "rotateRight";
             break;
          case MotionEvent.ACTION_UP: 
            //setActivityBackgroundColor(0xff000000);
            direction = "stop";
             break;
          }
         return false;
      }  
 };

 private OnTouchListener leftButtonListener = new OnTouchListener(){
     public boolean onTouch(View v, MotionEvent event) {
        switch ( event.getAction() ) {
         case MotionEvent.ACTION_DOWN: 
            //setActivityBackgroundColor(0xffff0000);
            direction = "rotateLeft";
             break;
         case MotionEvent.ACTION_UP: 
            //setActivityBackgroundColor(0xff000000);
            direction = "stop";
             break;
         }
        return false;
     }  
};


//save and retrieve IP address using the shared preferences framework
 private void saveIP(String IP)
 {
    //set up shared preferences editor
     pref = getApplicationContext().getSharedPreferences("RobotClient", 0); 
     Editor editor = pref.edit();
     editor.putString("robotIP", IP); 
     editor.commit();
 }

 private String loadIP()
 {
 String result;

 pref = getApplicationContext().getSharedPreferences("RobotClient", 0); 
 Editor editor = pref.edit();
 result = pref.getString("robotIP", "10.20.30.43");

 return result;
 }

 private void setActivityBackgroundColor(int color) {
        //0xff00ff00  first two are transparency, then rgb

        View view = this.getWindow().getDecorView();
        view.setBackgroundColor(color);
    }

 //periodically run updater to set connection status and wifi signal strength from robot
 private void updateGUI()
    {
        GUIUpdateHandler.postDelayed(GUIUpdater, 1000);
    }

 private Runnable GUIUpdater = new Runnable(){

        public void run() {
            //Periodically update GUI elements from sensor and other data
            Log.d(TAG,"Connected is: " + robotConnected.toString());

            //update connection status
            if (robotConnected)
            {
                connectedLED.setImageResource(R.drawable.led_green);

                //update the wifi signal strength indicator
                if ((signalStrength == 5) || (signalStrength==4))
                    signalStrengthIndicator.setImageResource(R.drawable.wifi4);

                if (signalStrength == 3) 
                        signalStrengthIndicator.setImageResource(R.drawable.wifi3);

                if (signalStrength == 2) 
                    signalStrengthIndicator.setImageResource(R.drawable.wifi2);

                if (signalStrength == 1) 
                    signalStrengthIndicator.setImageResource(R.drawable.wifi1);

                if (signalStrength == 0) 
                    signalStrengthIndicator.setImageResource(R.drawable.wifi0);
            }

            else
                {
                connectedLED.setImageResource(R.drawable.led_red);
                signalStrengthIndicator.setImageResource(R.drawable.wifi0);
                }

            if (stayConnected)          
                updateGUI();
        }

    };

 public void setConnected(boolean connected) {

    robotConnected = connected;
    }

 public void socketCleanup()
    {
        try {
        Log.d("clientThread","Socket Closing");
        if (s != null)
            s.close();
        setConnected(false);
        } catch (IOException e) {

        Log.d(TAG, "Client comm thread got IOException in socketCleanup().");
        }       
    }

 private void vidLoop() //started from GUI alert, then kept going with call me from asynctask
    {
        if (stayConnected)
            {
            ImageDownloader id = new ImageDownloader();
            id.execute(vidURL); 
            }
    }

    //this very useful chunk of code is from http://www.peachpit.com/articles/article.aspx?p=1823692&seqNum=3
 private class ImageDownloader extends AsyncTask<String, Integer, Bitmap>{
    protected void onPreExecute(){

        }
        @Override
        protected Bitmap doInBackground(String... params) {
            //TODO Auto-generated method stub
            try{
                URL url = new URL(params[0]);
                HttpURLConnection httpCon = 
                (HttpURLConnection)url.openConnection();
                if(httpCon.getResponseCode() != 200)
                    throw new Exception("Failed to connect");
                InputStream is = httpCon.getInputStream();
                return BitmapFactory.decodeStream(is);
            }catch(Exception e){
                Log.e("Image","Failed to load image",e);
            }
            return null;
        } 

        protected void onProgressUpdate(Integer... params){
            //Update a progress bar here, or ignore it, it's up to you
        }
        protected void onPostExecute(Bitmap img){
            ImageView iv = (ImageView)findViewById(R.id.imageView1);
            if(iv!=null && img !=null){
                iv.setImageBitmap(img);
                //start next image grab
                vidLoop();
            }
        }
            protected void onCancelled(){
            }
        }

class ClientThread implements Runnable {

        private static final int SERVERPORT = 8082;

        public void run() {
            Log.d("clientThread","clientThread started");
            setConnected(false);

            while ((!Thread.currentThread().isInterrupted()) && stayConnected)
            {
            controlLoop();
            }

            //user requested disconnect
            Log.d("clientThread","clientThread ending");
        }

        void controlLoop()
        {
            BufferedReader s_input = null;
            PrintWriter s_output = null;
            String inputString = null;
            String outputString = null;
            Boolean continueLoop = true;

            Log.d("clientThread","controlLoop starting");

             //protocol:
            //Java boolean: enabled or disabled 
            //Directions: stop, rotateRight, rotateLeft, forward, reverse
            //Client sends: robotEnabled,direction,servoPanValue
            //Server replies: sensor1,sensor2...

            continueLoop = true;

            try {

                InetAddress serverAddr = InetAddress.getByName(robotIP);
                Socket s = new Socket();
                //int timeout = 2000;   // DEFAULT milliseconds
                int timeout = 6000;   // milliseconds
                SocketAddress sockaddr = new InetSocketAddress(serverAddr, SERVERPORT);
                s.connect(sockaddr, timeout);

                s_input = new BufferedReader(new InputStreamReader(s.getInputStream()));
                s_output = new PrintWriter(s.getOutputStream(), true);

                } catch (UnknownHostException e1) {
                    e1.printStackTrace();
                    Log.d("clientThread","Got invalid IP string in client thread");
                    continueLoop = false;
                } catch (IOException e) {
                        Log.d("clientThread","Socket setup caught IOexception");
                        continueLoop = false;
//STACKEXCHANGE - THIS SEEMS TO BE WHERE THE CODE REPEATEDLY LOOPS AROUND TRYING TO CONNECT**********************************************************************************************
                    }
//STACKEXCHANGE - Loop starts below again and then logging "controlloop ending"
            Log.d("clientThread","Socket Established");

            setConnected(true);

            try {

                while ((stayConnected) && (continueLoop)) { 

                    speed = throttle.getProgress();

                    if (stayConnected)
                        outputString = robotEnabled.toString() + "," + direction.toString() + "," + speed.toString(); 
                    else 
                        outputString = "quit";

                    s_output.println(outputString);

                    if (!s_output.checkError())
                        {
                        inputString = s_input.readLine();

                        if (inputString == null)
                            {
                            continueLoop = false;
                            Log.d("clientThread","Unexpected disconnection.");
                            }
                        else
                        {
                        Log.d("clientThread","Client got: " + inputString.toString());
                        //parse returned string, which is just an integer containing the signal strength
                        try {
                            signalStrength = Integer.parseInt(inputString);
                            } catch(NumberFormatException nfe) {
                                Log.d(TAG,"Got invalid signal strength from client");
                            } 
                            }
                        }
                    else
                        {
                        //printwriter.checkError returned true, something bad happened network-wise
                        continueLoop = false;
                        Log.d("clientThread","Printwriter.checkError() returned true, likely network problem");
                        }
                }

             socketCleanup();
             Log.d("clientThread","controlLoop ending");
             //STACKEXCHANGE - This is also logged in the catlog at the end of repetitive loop
            } catch (IOException e) {
                //this happens if the connection times out.
                Log.d("clientThread", "Client comm thread got IOException in control loop.");
                socketCleanup();
            }    

        }//end control loop

    } //end client thread

}

Answer 1

这是因为你没有修改stayConnected。你不断地打电话

while ((!Thread.currentThread().isInterrupted()) && stayConnected)
{
    controlLoop();
}

并且每次调用都会出现异常。仅将 continueLoop 修改为 false。您应该在这种情况下中断您的 while 或根据您的预期行为中断您的线程；或者其他一些方法也可以。