Question

我的Android应用将大量文件发送到Amazon S3。每个文件URI都通过单独的调用传递给执行上传的IntentService。

但是，我想知道处理故障的最佳方法是什么......我应该用IntentService的{{1}}方法检测到失败并在同一方法中重试，或者我应该允许在方法之外处理失败（如果是，如何处理？）？

我个人倾向于第一个建议，因为我希望在尝试上传后续文件之前成功上传任何文件，但我不确定是否在onHandleIntent()方法中检测错误并执行重试是好的做法（？）。

Answer 1

这是一个非常好的问题。我在一次采访中被问到这个问题而我没有回答。但在寻找答案之后，我会尝试在这里回答。

步骤1：启动IntentService。您可以从Activity或Fragment启动IntentService。

/* Starting Download Service */

DownloadResultReceiver mReceiver = new DownloadResultReceiver(new Handler());
mReceiver.setReceiver(this);
Intent intent = new Intent(Intent.ACTION_SYNC, null, this, DownloadService.class);

/* Send optional extras to Download IntentService */
intent.putExtra("url", url);
intent.putExtra("receiver", mReceiver);
intent.putExtra("requestId", 101);
startService(intent);

Step-2：创建扩展IntentService的类。

public class DownloadService extends IntentService {

    public static final int STATUS_RUNNING = 0;
    public static final int STATUS_FINISHED = 1;
    public static final int STATUS_ERROR = 2;

    private static final String TAG = "DownloadService";

    public DownloadService() {
        super(DownloadService.class.getName());
    }

    @Override
    protected void onHandleIntent(Intent intent) {

        Log.d(TAG, "Service Started!");

        final ResultReceiver receiver = intent.getParcelableExtra("receiver");
        String url = intent.getStringExtra("url");

        Bundle bundle = new Bundle();

        if (!TextUtils.isEmpty(url)) {
            /* Update UI: Download Service is Running */
            receiver.send(STATUS_RUNNING, Bundle.EMPTY);

            try {
                String[] results = downloadData(url);//make your network call here and get the data or download a file.

                /* Sending result back to activity */
                if (null != results && results.length > 0) {
                    bundle.putStringArray("result", results);
                    receiver.send(STATUS_FINISHED, bundle);
                }
            } catch (Exception e) {

                /* Sending error message back to activity */
                bundle.putString(Intent.EXTRA_TEXT, e.toString());
                receiver.send(STATUS_ERROR, bundle);
            }
        }
        Log.d(TAG, "Service Stopping!");
        this.stopSelf();
    }
}

步骤3：要从IntentService接收结果，我们可以使用ResultReciever的子类。从Service发送结果后，将调用onReceiveResult（）方法。您的活动处理此响应并从Bundle中获取结果。收到结果后，活动实例会相应地更新UI。

public class DownloadResultReceiver extends ResultReceiver {
    private Receiver mReceiver;

    public DownloadResultReceiver(Handler handler) {
        super(handler);
    }

    public void setReceiver(Receiver receiver) {
        mReceiver = receiver;
    }

    public interface Receiver {
        public void onReceiveResult(int resultCode, Bundle resultData);
    }

    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        if (mReceiver != null) {
            mReceiver.onReceiveResult(resultCode, resultData);
        }
    }
}

步骤4：在您的MainActivity中：

@Override
    public void onReceiveResult(int resultCode, Bundle resultData) {
        switch (resultCode) {
            case DownloadService.STATUS_RUNNING:
                //progress bar visible.
                break;
            case DownloadService.STATUS_FINISHED:
                /* Hide progress & extract result from bundle */
                /* Update ListView with result */
                break;
            case DownloadService.STATUS_ERROR:
                /* Handle the error */
                String error = resultData.getString(Intent.EXTRA_TEXT);
                Toast.makeText(this, error, Toast.LENGTH_LONG).show();
                /*It is here, i think, that you can again check (eg your net connection) and call the IntentService to restart fetching of data from the network. */  
                break;
        }
    }

我希望上面的答案可以帮到你。任何改善答案的建议都是最受欢迎的。谢谢。

Android - 重试IntentService的最佳实践

1 个答案: