我正在尝试使用AlarmManager和BroadcastReceiver从关闭的应用程序启动活动。即使关闭应用程序或在后台运行,也会显示“已接收”调试消息,这意味着AlarmManager的工作方式与我希望的一样。但是只有在应用程序处于活动状态时才启动CameraActivity。有人知道为什么它不起作用吗?这是我的一些代码:
MainActivity:
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
...
Intent intent = new Intent(this, AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
alarmManager.setRepeating(
AlarmManager.RTC_WAKEUP,
startTimeStamp,
intervalTime,
pendingIntent);
Log.i("########################DEBUG", "started");
}
}
AlarmReceiver
public class AlarmReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Log.i("########################DEBUG", "received");
Intent launchIntent = new Intent(context, CameraActivity.class);
launchIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
context.startActivity(launchIntent);
/* Tried this too, didn't work
PackageManager packageManager = context.getPackageManager();
Intent launchIntent = packageManager.getLaunchIntentForPackage(CameraActivity.class.getName());
context.startActivity(launchIntent);*/
}
}
CameraActivity
public class CameraActivity extends AppCompatActivity {
private final int CAMERA_REQUEST = 1;
private ImageView image;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
image = findViewById(R.id.imageview);
Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
//startActivityForResult(cameraIntent, CAMERA_REQUEST);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
if (resultCode == RESULT_OK && requestCode == CAMERA_REQUEST) {
Bitmap photo = (Bitmap) data.getExtras().get("data");
image.setImageBitmap(photo);
}
}
}
manifest.xml
<application
...
<activity android:name=".CameraActivity">
</activity>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<receiver android:name=".AlarmReceiver" />
</application>
提前感谢!
根据Android 10的documentation,您的应用在后台运行时无法启动活动,除非涉及用户交互的情况非常有限。
文档指南提供了通知,作为从后台开始活动的替代方法。然后,本指南列出了不适用限制的特定情况。它建议显示Time-sensitive notification以向用户提供紧急信息,而不是直接启动活动或全屏意图。