android.os.PowerManager.WakeLock#isHeld ( )源码实例Demo

/**
 * @param tag will be prefixed with "signal:" if it does not already start with it.
 */
public static void release(@Nullable WakeLock wakeLock, @NonNull String tag) {
  tag = prefixTag(tag);
  try {
    if (wakeLock == null) {
      Log.d(TAG, "Wakelock was null. Skipping. Tag: " + tag);
    } else if (wakeLock.isHeld()) {
      wakeLock.release();
      Log.d(TAG, "Released wakelock with tag: " + tag);
    } else {
      Log.d(TAG, "Wakelock wasn't held at time of release: " + tag);
    }
  } catch (Exception e) {
    Log.w(TAG, "Failed to release wakelock with tag: " + tag, e);
  }
}
 

/**
 * Releases a partial {@link WakeLock} with a tag contained in the given{@link Intent}
 *
 * @param intent intent*/
private void releasePartialWakeLock(Intent intent) {
    if (intent.hasExtra(WakeLockManager.EXTRA_WAKELOCK_TAG)) {
        final int hash = intent.getIntExtra(WakeLockManager.EXTRA_WAKELOCK_HASH, -1);
        final String tag = intent.getStringExtra(WakeLockManager.EXTRA_WAKELOCK_TAG);
        // We use copy on write list. Iterator won't cause ConcurrentModificationException
        for (WakeLock wakeLock : wakeLocks) {
            if (hash == wakeLock.hashCode()) {
                if (wakeLock.isHeld()) {
                    wakeLock.release();
                    LogUtils.d("releasePartialWakeLock: " + wakeLock.toString() + " " + tag + " was released");
                } else {
                    LogUtils.d("releasePartialWakeLock: " + wakeLock.toString() + " " + tag + " was already released!");
                }
                wakeLocks.remove(wakeLock);
                return;
            }
        }
        LogUtils.e("releasePartialWakeLock: " + "Hash " + hash + " was not found");
    }
}
 

/**
 * 保持屏幕常亮
 *
 * @param activity you know
 */
public static void keepScreenOn(Activity activity) {
    WakeLock wakeLock = mWakeLockArray.get(activity);
    if (wakeLock == null) {
        PowerManager powerManager = (PowerManager) activity.getSystemService(Context.POWER_SERVICE);
        wakeLock = powerManager.newWakeLock(PowerManager.ACQUIRE_CAUSES_WAKEUP | PowerManager.FULL_WAKE_LOCK,
                activity.getClass().getName());
    }

    if (!wakeLock.isHeld()) {
        wakeLock.acquire();
    }

    mWakeLockArray.put(activity, wakeLock);

    cancelLockScreen(activity);

    Log.i(TAG, "开启屏幕常亮");
}
 

private boolean _acquireWakeLock(WakeLock lock, long timeout) {
    synchronized (lock) {
        if (!lock.isHeld()) {
            if (timeout > 0) {
                lock.acquire(timeout);
            } else {
                lock.acquire();
            }
            return true;
        }
    }
    return false;
}
 

private boolean _releaseWakeLock(WakeLock lock) {
    synchronized (lock) {
        if (lock.isHeld()) {
            lock.release();
            return true;
        }
    }
    return false;
}
 

/**
 * 取消屏幕常亮
 *
 * @param activity you know
 */
public static void cancelKeepScreen(Activity activity) {
    WakeLock wakeLock = mWakeLockArray.get(activity);
    if (wakeLock != null) {
        if (wakeLock.isHeld()) {
            wakeLock.release();
        }
    }

    Log.i(TAG, "取消屏幕常亮");
}
 

private boolean _acquireWakeLock(WakeLock lock, long timeout) {
    synchronized (lock) {
        if (!lock.isHeld()) {
            if (timeout > 0) {
                lock.acquire(timeout);
            } else {
                lock.acquire();
            }
            return true;
        }
    }
    return false;
}
 

private boolean _releaseWakeLock(WakeLock lock) {
    synchronized (lock) {
        if (lock.isHeld()) {
            lock.release();
            return true;
        }
    }
    return false;
}
 

public static synchronized void acquire(Context context) {
	WakeLock wakeLock = getLock(context);
	if (!wakeLock.isHeld()) {
		wakeLock.acquire();
		//Log.d("alogcat", "wake lock acquired");
	}
}
 

@Override
protected Boolean doInBackground(String... strParams)
{
    Boolean result = Boolean.FALSE;

    // get a wakelock to hold for the duration of the background work. downloading
    // may be slow. extraction usually isn't too slow but also takes a bit of time. limit the wakelock's time!
    PowerManager powerManager = (PowerManager)m_ctx.getSystemService(Context.POWER_SERVICE);
    WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "SettingsDownloaderWakeLock");
    wakeLock.acquire(FOUR_MINUTES);

    // download the file
    String filename = downloadFile(strParams[0]);
    if (filename != null)
    {
        File fSettingsZip = new File(filename);
        if (fSettingsZip.exists() && !isCancelled())
        {
            try
            {
                m_logWriter.write("Successfully downloaded to: "+filename+"\n");

                // extract to wanted directory
                String destDir = strParams[1];
                boolean bSuccess = extractSettingsZip(fSettingsZip, destDir);
                result = (bSuccess ? Boolean.TRUE : Boolean.FALSE);

                // delete settings zip
                if (fSettingsZip.exists()) {
                    fSettingsZip.delete();
                }
            }
            catch(Exception e)
            {
                Log.e("SettingsDownloader", "Error: "+e.toString());
            }
        }
    }

    // if our max time hasn't passed but work is done or an error occurred we bail out and release
    if (wakeLock.isHeld())
    {
        wakeLock.release();
    }

    return result;
}