问IntentService遍历一个列表，该列表可以通过onHandleIntent并发地重新排序

EN

public class PBQDownloader extends IntentService {
    int currentWeight = 0;
    PriorityBlockingQueue<WeightedAsset> pbQueue = new PriorityBlockingQueue<WeightedAsset>(100, new CompareWeightedAsset());
    public PBQDownloader() {
        super("PBQDownloader");
    }
    public PBQDownloader(String name) {
        super(name);
    }
    @Override
    protected void onHandleIntent(Intent intent) {
        String downloadUrl = "-NULL-";
        Bundle extras = intent.getExtras();
        if (extras!=null) {
            downloadUrl = extras.getString("url");
            Log.d("onHandleIntent 1.1", "asked to download: " + downloadUrl);
        } else {
            Log.d("onHandleIntent 1.2", "no URL sent so let's start queueing everything");
            int MAX = 10;
            for (int i = 1; i <= MAX; i++) {
                // should read URLs from list
                WeightedAsset waToAdd = new WeightedAsset("url: " + i, MAX - i);
                if (pbQueue.contains(waToAdd)) {
                    Log.d("onStartCommand 1", downloadUrl + " already exists, so we are removing it and adding it back with a new priority");
                    pbQueue.remove(waToAdd); 
                }
                pbQueue.put(waToAdd);
            }
            currentWeight = MAX + 1;
        }
        while (!pbQueue.isEmpty()) {
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
            }
            WeightedAsset waToProcess = pbQueue.poll();
            Log.d("onHandleIntent 2 DOWNLOADED", waToProcess.url);
        }
        Log.d("onHandleIntent 99", "finished all IntentService calls");
    }
    @Override
    public int onStartCommand(Intent intent, int a, int b) {
        super.onStartCommand(intent, a, b);
        currentWeight++;
        String downloadUrl = "-NULL-";
        Bundle extras = intent.getExtras();
        if (extras!=null) downloadUrl = extras.getString("url");
        Log.d("onStartCommand 0", "download: " + downloadUrl + " with current weight: " + currentWeight);
        WeightedAsset waToAdd = new WeightedAsset(downloadUrl, currentWeight);
        if (pbQueue.contains(waToAdd)) {
            Log.d("onStartCommand 1", downloadUrl + " already exists, so we are removing it and adding it back with a new priority");
            pbQueue.remove(waToAdd); 
        }
        pbQueue.put(waToAdd);
        return 0;
    }
    private class CompareWeightedAsset implements Comparator<WeightedAsset> {
        @Override
        public int compare(WeightedAsset a, WeightedAsset b) {
            if (a.weight < b.weight) return 1;
            if (a.weight > b.weight) return -1;
            return 0;
        }
    }
    private class WeightedAsset {
        String url;
        int weight;
        public WeightedAsset(String u, int w) {
            url = u;
            weight = w;
        }
    }
}

public class HelloPBQ extends Activity {
    int sCount = 10;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button tv01 = (Button) findViewById(R.id.tv01);
        Button tv02 = (Button) findViewById(R.id.tv02);
        Button tv03 = (Button) findViewById(R.id.tv03);
        tv01.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                doPBQ();
            }
        });
        tv02.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                doInitPBQ();
            }
        });
        tv03.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                sCount = 0;
            }
        });
    }

    private void doInitPBQ() {
        Intent intent = new Intent(getApplicationContext(), PBQDownloader.class);
        //intent.putExtra("url", "url: " + sCount);
        startService(intent);
    }    
    private void doPBQ() {
        sCount++;
        Intent intent = new Intent(getApplicationContext(), PBQDownloader.class);
        intent.putExtra("url", "url: " + sCount);
        startService(intent);
    }
}