程序目的：我正在尝试制作一个应用程序，通过发出 Intent.ACTION_SCREEN_ON 广播来计算用户检查手机的次数。然后它增加一个计数器并用新的计数器更新活动。
问题：这一切都很好，但是一旦我从应用程序托盘中滑动应用程序，计数器就会回到零。 显然应该发生的是计数器将继续。我尝试将计数器值保存在服务 onDestroy 中，然后再次调用它 onCreate 但从未调用过 onDestroy。
请注意，在活动的 onCreate() 中，它向服务发送广播，询问计数器的最新值，然后在视图中更新它。我找不到更好的方法让它们保持同步。
CounterService.java
public class CounterService extends Service {
public static boolean RERUN = true;
private int counter = 0;
private SharedPreferences SP;
private BroadcastReceiver mScreenStateBroadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
counter++;
System.out.println("************************************* \n \n " + counter);
}
sendCounterBroadcast();
}
};
public void sendCounterBroadcast() {
Intent i = new Intent();
i.setAction("com.inc.count");
i.putExtra("counterValue", counter);
sendBroadcast(i);
}
@Override
public void onCreate() {
super.onCreate();
System.out.println("********************** CounterService.onCreate()");
// get counter value from SP -- this is useful for when the service gets recreated
SP = getSharedPreferences("Counter Service Data", MODE_PRIVATE);
counter = SP.getInt("counter", 0);
// wait for screen to be turned on or for the activity to ask you for the counter number
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(Intent.ACTION_SCREEN_ON);
intentFilter.addAction("send.counter.to.phonecounteractivity");
registerReceiver(mScreenStateBroadcastReceiver, intentFilter);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
return Service.START_STICKY;
}
@Override
public void onDestroy() {
super.onDestroy();
System.out.println("***************************************** CounterService.OnDestroy()");
unregisterReceiver(mScreenStateBroadcastReceiver);
// Save counter value for when we restart service
SP = getSharedPreferences("Counter Service Data", MODE_PRIVATE);
SharedPreferences.Editor SPE = SP.edit();
if (RERUN) {
SPE.putInt("counter", counter);
System.out.println("******************************** RESTARTING SERVICE ");
startService(new Intent(getApplicationContext(), CounterService.class));
} else
SPE.putInt("counter", 0);
SPE.apply();
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
}
PhoneCheckerCounter.Java
public class PhoneCheckerCounter extends AppCompatActivity {
private BroadcastReceiver changeCount;
private IntentFilter filter;
private int counter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_phone_checker_counter);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
switcherOnClick();
assignValuesOnCreate();
System.out.println("**************************** onCreate()");
changeCounterText();
}
public void switcherOnClick() {
final Switch sCounter = findViewById(R.id.switchCounter);
sCounter.setOnClickListener(new View.OnClickListener() {
Intent intent = new Intent(getApplicationContext(), CounterService.class);
@Override
public void onClick(View v) {
if (sCounter.isChecked()) {
startService(intent);
CounterService.RERUN = true;
v.getContext().registerReceiver(changeCount, filter);
Toast.makeText(getApplicationContext(), "Counting has begun", Toast.LENGTH_SHORT).show();
} else {
TextView n = findViewById(R.id.counter);
n.setText("0");
CounterService.RERUN = false;
v.getContext().unregisterReceiver(changeCount);
stopService(intent);
Toast.makeText(getApplicationContext(), "The application stopped counting", Toast.LENGTH_SHORT).show();
}
}
});
}
public void changeCounterText() {
changeCount = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
TextView n = findViewById(R.id.counter);
counter = intent.getIntExtra("counterValue", 0);
System.out.println("************************ RECEIVED!!!! value of: " + counter);
n.setText("" + counter);
}
};
filter = new IntentFilter();
filter.addAction("com.inc.count");
this.registerReceiver(changeCount, filter);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(changeCount);
assignValuesOnDestroy();
System.out.println("**************************** onDestroy()");
}
public void assignValuesOnCreate() {
Switch s = findViewById(R.id.switchCounter);
if (getSwitchValueFromSP() == 1) s.setChecked(true);
else s.setChecked(false);
Intent f = new Intent();
f.setAction("send.counter.to.phonecounteractivity");
sendBroadcast(f);
}
public void assignValuesOnDestroy() {
SharedPreferences SP = getSharedPreferences("data", MODE_PRIVATE);
SharedPreferences.Editor edit = SP.edit();
Switch s = findViewById(R.id.switchCounter);
if (s.isChecked()) edit.putInt("switch", 1);
else edit.putInt("switch", 0);
edit.apply();
}
public int getSwitchValueFromSP() {
SharedPreferences SP = getSharedPreferences("data", MODE_PRIVATE);
int isOn = SP.getInt("switch", 0);
return isOn;
}
}
