Java 从IntentService调度递归处理程序以重试http调用

我正试图通过在每次请求失败时使用

handler.postDelayed（…）

调度线程来实现指数退避，以重试失败的http调用。问题是，我是从一个IntentService执行此操作的，它在调度第一个线程后死亡，因此处理程序无法调用自己。我得到以下错误：

java.lang.IllegalStateException: Handler (android.os.Handler) {2f31b19b} sending message to a Handler on a dead thread

我的IntentService课程：

@Override
    protected void onHandleIntent(Intent intent) {

        ......

        Handler handler = new Handler();
        HttpRunnable httpRunnable = new HttpRunnable(info, handler);
        handler.postDelayed(httpRunnable, 0);

}

我的自定义Runnable：

public class HttpRunnable implements Runnable {

  private String info;
  private static final String TAG = "HttpRunnable";
  Handler handler = null;
  int maxTries = 10;
  int retryCount = 0;
  int retryDelay = 1000; // Set the first delay here which will increase exponentially with each retry

  public HttpRunnable(String info, Handler handler) {
    this.info = info;
    this.handler = handler;
  }

  @Override
  public void run() {
    try {
        // Call my class which takes care of the http call
        ApiBridge.getInstance().makeHttpCall(info);
    } catch (Exception e) {
        Log.d(TAG, e.toString());
        if (maxTries > retryCount) {
        Log.d(TAG,"%nRetrying in " + retryDelay / 1000 + " seconds");
            retryCount++;
            handler.postDelayed(this, retryDelay);
            retryDelay = retryDelay * 2;
        }
    }
  }
}

---

有没有办法让我的主人活着？使用指数退避来安排http重试的最佳/最干净的方法是什么？

使用

IntentService

的主要优点是它在

onHandleIntent（Intent-Intent）

方法中为您处理所有后台线程。在这种情况下，您没有理由自己管理处理程序

下面是一种方法，您可以使用

AlarmManager

来计划向您的服务交付意图。您可以将重试信息保存在要传递的意图中

我是这样想的：

public class YourService extends IntentService {

    private static final String EXTRA_FAILED_ATTEMPTS = "com.your.package.EXTRA_FAILED_ATTEMPTS";
    private static final String EXTRA_LAST_DELAY = "com.your.package.EXTRA_LAST_DELAY";
    private static final int MAX_RETRIES = 10;
    private static final int RETRY_DELAY = 1000;

    public YourService() {
        super("YourService");
    }

    @Override
    protected final void onHandleIntent(Intent intent) {

        // Your other code obtaining your info string.

        try {
            // Make your http call.
            ApiBridge.getInstance().makeHttpCall(info);
        } catch (Exception e) {
            // Get the number of previously failed attempts, and add one.
            int failedAttempts = intent.getIntExtra(EXTRA_FAILED_ATTEMPTS, 0) + 1;
            // if we have failed less than the max retries, reschedule the intent
            if (failedAttempts < MAX_RETRIES) {
                // calculate the next delay
                int lastDelay = intent.getIntExtra(EXTRA_LAST_DELAY, 0);
                int thisDelay;
                if (lastDelay == 0) {
                    thisDelay = RETRY_DELAY;
                } else {
                    thisDelay = lastDelay * 2;
                }
                // update the intent with the latest retry info
                intent.putExtra(EXTRA_FAILED_ATTEMPTS, failedAttempts);
                intent.putExtra(EXTRA_LAST_DELAY, thisDelay);
                // get the alarm manager
                AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
                // make the pending intent
                PendingIntent pendingIntent = PendingIntent
                        .getService(getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
                // schedule the intent for future delivery
                alarmManager.set(AlarmManager.RTC_WAKEUP,
                        System.currentTimeMillis() + thisDelay, pendingIntent);
            }
        }
    }
}

---

我想您可以使用共享的首选项来存储请求代码，每次您必须计划重试时，该代码都会递增。

非常好而且符合逻辑，谢谢！我不得不通过将getService的最后一个参数更改为“PendingEvent.FLAG_UPDATE_CURRENT”来进行一个小的修正

int requestCode = getNextRequestCode();
PendingIntent pendingIntent = PendingIntent
    .getService(getApplicationContext(), requestCode, intent, 0);