方式一：
/** * 在Application内添加监听 */ public void registerListenerLifecycle(){ registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() { @Override public void onActivityCreated(@NonNull Activity activity, @Nullable Bundle savedInstanceState) { } @Override public void onActivityStarted(@NonNull Activity activity) { } @Override public void onActivityResumed(@NonNull Activity activity) { } @Override public void onActivityPaused(@NonNull Activity activity) { } @Override public void onActivityStopped(@NonNull Activity activity) { } @Override public void onActivitySaveInstanceState(@NonNull Activity activity, @NonNull Bundle outState) { } @Override public void onActivityDestroyed(@NonNull Activity activity) { } }); }方式二： 替换Instrumentation
//在 Application内初始化 public class TopActivityGet { private TopActivityGet(){} private static TopActivityGet instance; private static CInstrumentation cInstrumentation; private Activity activity; public static TopActivityGet getInstance(){ if (instance == null){ synchronized (TopActivityGet.class){ if (instance == null){ instance = new TopActivityGet(); init(); } } } return instance; } private static void init(){ try { cInstrumentation = new CInstrumentation(); Class cls = Class.forName("android.app.ActivityThread"); // ActivityThread被隐藏了，所以通过这种方式获得class对象 Method mthd = cls.getDeclaredMethod("currentActivityThread", (Class[]) null); // 获取当前ActivityThread对象引用 Object currentAT = null; currentAT = mthd.invoke(null, (Object[]) null); Field mInstrumentation = currentAT.getClass().getDeclaredField("mInstrumentation"); mInstrumentation.setAccessible(true);//设置private变量为可读取 mInstrumentation.set(currentAT, cInstrumentation); // 修改ActivityThread.mInstrumentation值 } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } catch (NoSuchMethodException e) { e.printStackTrace(); } catch (NoSuchFieldException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public Activity getTopActivity(){ return activity; } public void setTopActivity(Activity activity){ this.activity = activity; } } public class CInstrumentation extends Instrumentation { @Override public void callActivityOnResume(Activity activity) { super.callActivityOnResume(activity); TopActivityGet.getInstance().setTopActivity(activity); } }监听其他应用的最高Activity：需要向用户申请权限
public class AppMonitoringService extends AbsWorkService { private UsageStatsManager manager; @TargetApi(Build.VERSION_CODES.LOLLIPOP) @Override public int onStartCommand(Intent intent, int flags, int startId) { manager = (UsageStatsManager) getSystemService(USAGE_STATS_SERVICE); startMonitoring(); return START_STICKY; } //.... @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) private void startMonitoring(){ UsageEvents usageEvents = manager.queryEvents(startTime, endTime); UsageEvents.Event event = new UsageEvents.Event(); //遍历这个事件集合，如果还有下一个事件 while (usageEvents.hasNextEvent()){ //得到下一个事件放入event中,先得得到下个一事件，如果这个时候直接调用，则 event的package是null，type是0。 usageEvents.getNextEvent(event); //如果这是个将应用置于前台的事件 if(event.getEventType() == UsageEvents.Event.MOVE_TO_FOREGROUND){ //............. } } } }