Question

我在使用HandlerThread和Handlers时遇到了一个奇怪的问题（By Handlers我的意思是android.os.handler）。我试图将消息从我的片段传递给单独的处理程序线程。我只是设置一个handleMessage来处理消息。但它没有被称为。在使用start（）启动线程之后（在准备好looper之后）我得到了处理程序线程的looper。我还检查了处理程序使用hasMessage（）获取消息。一切都好。我很迷惑。请帮助我。我的代码在下面。

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();
    }
}

HandlerThread

 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：

我能够发送消息，我可以从另一个线程接收到来自handleMessage（）的消息。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Handler，将线程作为Callback传递（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);

不调用HandlerThread的handleMessage（）

1 个答案: