Question

我创建了简单的服务，每隔一秒就要记录一次。我使用了警报管理器（因为来自official document说Note: The Alarm Manager is intended for cases where you want to have your application code run at a specific time, even if your application is not currently running.）但它随机重复。这是我的代码

MainActiviry.class

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

       FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        if (fab != null) {
            fab.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(MainActivity.this,LogService.class);
                    startService(intent);
                }
            });
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

点击FAB按钮开始服务。

LogService.class

public class LogService extends Service {
    private static final String TAG = LogService.class.getSimpleName();

    public LogService() {
        super();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.e(TAG, "onStartCommand: Service calling" );

        return super.onStartCommand(intent, flags, startId);
    }


    @Override
    public void onDestroy() {
        super.onDestroy();
    }

    @Override
    public void onCreate() {
        Timer(this);
        super.onCreate();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    private void Timer(Context context){
        Intent  intent = new Intent(context,LogService.class);
        PendingIntent pendingIntent = PendingIntent.getService(context,0,intent,0);
        AlarmManager alarmManager = (AlarmManager) getApplicationContext().getSystemService(getApplicationContext().ALARM_SERVICE);
        alarmManager.setRepeating(alarmManager.RTC_WAKEUP,System.currentTimeMillis(),1*1000,pendingIntent);
    }
}

这是我的 LOG

它每分钟都在重复，但我每秒钟都在写。我犯了什么错吗？

Answer 1

由于API 19重复警报不准确。见：

注意：从API 19开始，所有重复警报都不准确。如果您的应用程序需要精确的交付时间，那么它必须使用一次性精确警报，每次重新安排如上所述。 targetSdkVersion早于API 19的旧应用程序将继续将所有警报（包括重复警报）视为完全警报。

您必须将targetSdkVersion设置为低于19的值或使用一次性精确警报并每次重新设置它们。

这是official documentation

使用java.util.Timer

的简单解决方案

Timer timer = new Timer();
            timer.scheduleAtFixedRate(new TimerTask() {

                @Override
                public void run() {
                    //Put your code here
                    Log.d("Log", "Hello World");
                }
            }, 0, 1000);

警报管理器在服务中重复异常

1 个答案: