Android 如何监控当前Foreground Activity，如何获知应用程序的启动

4. Merge this into your AndroidManifest.xml

<application> <service android:label="@string/accessibility_service_name" android:name=".WindowChangeDetectingService" android:permission="android.permission.BIND_ACCESSIBILITY_SERVICE"> <intent-filter> <action android:name="android.accessibilityservice.AccessibilityService"/> </intent-filter> <meta-data android:name="android.accessibilityservice" android:resource="@xml/accessibilityservice"/> </service> </application> [title2]5. Put this in res/xml/accessibilityservice.xml:[/title2] <?xml version="1.0" encoding="utf-8"?> <!-- These options MUST be specified here in order for the events to be received on first start in Android 4.1.1 --> <accessibility-service xmlns:tools="http://schemas.android.com/tools" android:accessibilityEventTypes="typeWindowStateChanged" android:accessibilityFeedbackType="feedbackGeneric" android:accessibilityFlags="flagIncludeNotImportantViews" android:description="@string/accessibility_service_description" xmlns:android="http://schemas.android.com/apk/res/android" tools:ignore="UnusedAttribute"/>

6. Enabling the Service

二、使用 ActivityManager

ActivityManager.RunningAppProcessInfo.processState

3. 代码示例：

public class CurrentApplicationPackageRetriever {
private final Context context;
public CurrentApplicationPackageRetriever(Context context) {
this.context = context;
}
public String[] get() {
if (Build.VERSION.SDK_INT < 21)
return getPreLollipop();
else
return getLollipop();
}
private String[] getPreLollipop() {
@SuppressWarnings("deprecation")
List<ActivityManager.RunningTaskInfo> tasks =
activityManager().getRunningTasks(1);
ActivityManager.RunningTaskInfo currentTask = tasks.get(0);
ComponentName currentActivity = currentTask.topActivity;
return new String[] { currentActivity.getPackageName() };
}

private String[] getLollipop() {
final int PROCESS_STATE_TOP = 2;
try {
Field processStateField = ActivityManager.RunningAppProcessInfo.class.getDeclaredField("processState");

List<ActivityManager.RunningAppProcessInfo> processes =
activityManager().getRunningAppProcesses();
for (ActivityManager.RunningAppProcessInfo process : processes) {
if (
// Filters out most non-activity processes
process.importance <= ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND
&&
// Filters out processes that are just being
// _used_ by the process with the activity
process.importanceReasonCode == 0
) {
int state = processStateField.getInt(process);

if (state == PROCESS_STATE_TOP)
/*
If multiple candidate processes can get here,
it's most likely that apps are being switched.
The first one provided by the OS seems to be
the one being switched to, so we stop here.
*/
return process.pkgList;
}
}
} catch (NoSuchFieldException | IllegalAccessException e) {
throw new RuntimeException(e);
}
return new String[] { };
}

private ActivityManager activityManager() {
return (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
}
}

4. 添加 GET_TASKS 权限到

AndroidManifest.xml

:

<!--suppress DeprecatedClassUsageInspection -->
<uses-permission android:name="android.permission.GET_TASKS" />

三、通过反射"android.app.ActivityThread"的方式获取Top Activity

public static Activity getRunningActivity() {
try {
Class activityThreadClass = Class.forName("android.app.ActivityThread");
Object activityThread = activityThreadClass.getMethod("currentActivityThread")
.invoke(null);
Field activitiesField = activityThreadClass.getDeclaredField("mActivities");
activitiesField.setAccessible(true);
ArrayMap activities = (ArrayMap) activitiesField.get(activityThread);
for (Object activityRecord : activities.values()) {
Class activityRecordClass = activityRecord.getClass();
Field pausedField = activityRecordClass.getDeclaredField("paused");
pausedField.setAccessible(true);
if (!pausedField.getBoolean(activityRecord)) {
Field activityField = activityRecordClass.getDeclaredField("activity");
activityField.setAccessible(true);
return (Activity) activityField.get(activityRecord);
}
}
} catch (Exception e) {
throw new RuntimeException(e);
}

throw new RuntimeException("Didn't find the running activity");
}

四、通过 UsageStatsManager
-> queryUsageStats方法获取Top Activity

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
UsageStatsManager usm = (UsageStatsManager) getSystemService("usagestats");
long time = System.currentTimeMillis();
List<UsageStats> appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);
if (appList != null && appList.size() > 0) {
SortedMap<Long, UsageStats> mySortedMap = new TreeMap<Long, UsageStats>();
for (UsageStats usageStats : appList) {
mySortedMap.put(usageStats.getLastTimeUsed(), usageStats);
}
if (mySortedMap != null && !mySortedMap.isEmpty()) {
currentApp = mySortedMap.get(mySortedMap.lastKey()).getPackageName();
}
}
} else {
List<ActivityManager.RunningAppProcessInfo> tasks = am.getRunningAppProcesses();
currentApp = tasks.get(0).processName;
}