HandlerThread的handleMessage()没有被调用

Question

我在使用 HandlerThread 和 Handlers（我指的是 android.os.handler）时遇到了一个奇怪的问题。我正在尝试将消息从我的片段传递到单独的处理程序线程。我只是设置了一个handleMessage 来处理消息。但它没有被调用。在使用 start() 启动线程后，我得到了处理程序线程的 looper（在准备好 looper 之后）。我还检查了处理程序是否使用 hasMessage() 获取了消息。一切顺利。我很迷惑。请帮助我。我的代码如下。

片段代码：

   package com.example.raaja.handlerone;

import android.app.Fragment;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;





/**
 * Created by Raaja on 08-12-2015.
 */
public class LoaderFragment extends Fragment {
    Button loaderButton;
    LoaderThread loadThread;
    Handler loaderThreadHandler;
    Handler loaderHandler;
    String[] queArray;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        loaderHandler = new Handler();
        loadThread = new LoaderThread("LoaderThread",loaderHandler);
         queArray = new String[]{"http://www.paynekillers.com/downloads/screens/17_screen05.jpg",
                "http://www.hdwallpapers.in/walls/jacob_frye_assassins_creed_syndicate-wide.jpg",
        "http://www.percivalconstantine.com/wp-content/uploads/2015/03/Tomb-Raider-Lara-Croft-Summit-2013.jpg",
        "http://orig00.deviantart.net/f904/f/2014/155/e/a/batman_arkham_knight_hd_wallpaper_1_by_rajivcr7-d7l19pt.jpg",
        "http://static5.gamespot.com/uploads/original/536/5360430/2753139-15774024117_9026e0a43c_o.jpg"};
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View loaderView = inflater.inflate(R.layout.loader_layout, container, false);
        this.loaderButton = (Button) loaderView.findViewById(R.id.proc_button);
        return loaderView;
    }

    @Override
    public void onResume() {
        super.onResume();



        loaderButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                loadThread.start();
                Looper loop = loadThread.requestLooper();
                loaderThreadHandler = new Handler(loop);
                Message msg = Message.obtain(loaderThreadHandler, 1, queArray);
                msg.sendToTarget();


            }
        });
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        loadThread.quit();
    }
}

处理线程

 package com.example.raaja.handlerone;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.util.Log;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

/**
 * Created by Raaja on 08-12-2015.
 */
public class LoaderThread extends HandlerThread implements Handler.Callback{
    Handler imageHandler;
    Map<Integer,String> queMap;
    HandlerActivity activity;

    public LoaderThread(String name, Handler handler) {
        super(name);
        imageHandler= handler;
        Log.d("inside : ", name);
    }

    Looper requestLooper(){

        Looper loop = this.getLooper();
        Log.d("In Thread : ", String.valueOf(loop.getThread().getName()));
        return loop.myLooper();
    }


    @Override
    public boolean handleMessage(Message msg) {
        String[] que = (String[]) msg.obj;
        queMap = new HashMap<Integer,String>();
        if(que != null){Log.d("",que[3]);}
        for (int i=0;i<=4; i++){
            String url = que[i];

            queMap.put(i,url);
            Log.d("1",url);
        }
        Random rand = new Random();
       String link = queMap.get(rand.nextInt(5));

        loadImages(link);
        return true;
    }

    void loadImages(final String url){
        Log.d("inside Load :","Inside Load");
        try {
            HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
            final Bitmap image = BitmapFactory.decodeStream(connection.getInputStream());
            imageHandler.post(new Runnable() {
                @Override
                public void run() {
                    activity.loadImage(image, url);
                }
            });

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


}

Answer 1

回答我的问题：

我可以发送消息，并且可以从另一个线程接收消息到我的 handleMessage()。我已经扩展了 HandlerThread 类并为我的 Thread 类实现了 Handler.Callback。所以我只是使用下面的版本来实例化一个将线程作为回调传递的处理程序（因为它实现了 Handler.Callback 它被接受为回调）。我希望它有所帮助。如果您感到困惑，请仔细阅读代码。谢谢。

Handler myHandler = new Handler(myThread.getLooper(),myThread);