Android中同一个Handler下载2幅图片，却只能显示1张图片。

Question

package cn.edu.siso.async;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.ImageView;
import android.widget.Toast;

public class ThreadDownloadImageActivity extends Activity {
/** Called when the activity is first created. */
private AsyncLoadHandler asynHandler;
private int id1;
private ImageView img2;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.threaddownload);

    id1 = R.id.ivThread1;
    img2 = (ImageView) findViewById(R.id.ivThread2);

    // 定义后台下载线程
    AsyncLoadPicThread1 asyncLoadPicThread1 = new AsyncLoadPicThread1();
    asynHandler = new AsyncLoadHandler();
    // 启动后台下载线程
    asyncLoadPicThread1.start();

    // 定义后台下载线程
    AsyncLoadPicThread2 asyncLoadPicThread2 = new AsyncLoadPicThread2();

    // 启动后台下载线程
    asyncLoadPicThread2.start();
}

// 下载图片线程1
public class AsyncLoadPicThread1 extends Thread {
    private String url = "http://img.52fuqing.com/upload/editor/2017-2-24/2017224111925866e5cze.png";

    @Override
    public void run() {
        try {
            Drawable drawable = Drawable.createFromStream(
                    new URL(url).openStream(), "01.jpg");
            Message message = asynHandler.obtainMessage();
            message.arg1 = id1;
            message.obj = drawable;
            message.what = 1;
            asynHandler.sendMessage(message);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

// 下载图片线程2
public class AsyncLoadPicThread2 extends Thread {
    private String url = "http://img1.gtimg.com/19/1905/190582/19058261_1200x1000_281.jpg";

    @Override
    public void run() {
        try {
            Drawable drawable = Drawable.createFromStream(
                    new URL(url).openStream(), "02.jpg");
            Message message2 = asynHandler.obtainMessage();
            // message.arg1 = id1;
            message2.obj = drawable;
            message2.what =2;
            asynHandler.sendMessage(message2);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

// 图片下载完成通知主线程显示图片
public class AsyncLoadHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {

        if (msg.what == 1) {

            ((ImageView) ThreadDownloadImageActivity.this
                    .findViewById(msg.arg1))
                    .setImageDrawable((Drawable) msg.obj);
        }
        if (msg.what == 2) {
            img2.setImageDrawable((Drawable) msg.obj);
        }

    }
}

// 捕获back按钮，关闭activity
public boolean onKeyDown(int keyCode, KeyEvent event) {

    if (keyCode == KeyEvent.KEYCODE_BACK) {
        finish();
    }
    return false;
}

}

Answer 1

楼主，我试了一下你的代码，没问题啊？我拷贝上面的代码，自己写了个布局，运行正常，你仔细检查一下，会不会是你上面的id1的id导错了，如果还没解决，可以发邮箱给我，[e-mail]