Android 获取activity栈中activity

方法1：

<!--获取Activity任务栈 权限-->
<uses-permission android:name="android.permission.GET_TASKS" />

// 获取activity任务栈
ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
ActivityManager.RunningTaskInfo info = manager.getRunningTasks(1).get(0);

String packageName = info.topActivity.getPackageName();
String topclassName = info.topActivity.getClassName();  
String baseclassname = info.baseActivity.getClassName();
int acitivitynum = info.numActivities;

 方法2：

在终端或者Android Studio中的Terminal里输入命令：

adb shell dumpsys activity activities

之后可以看到如下的activity栈输出信息：

方法3 （反射）：

转自：https://www.jianshu.com/p/ac0b237bac03 

Framewok层源码中，

public final class ActivityThread {
       ......
       final ArrayMap<IBinder, ActivityClientRecord> mActivities = new ArrayMap<>();
       ......
   }

这个Map的Value是ActivityClientRecord，持有Activity对象。

mLoadedApk持有ActivityThread，因此此处可以路反射过去拿到Map拿到ValueList

private static List<Activity> getActivitiesByApplication(Application application) {
        List<Activity> list = new ArrayList<>();
        try {
            Class<Application> applicationClass = Application.class;
            Field mLoadedApkField = applicationClass.getDeclaredField("mLoadedApk");
            mLoadedApkField.setAccessible(true);
            Object mLoadedApk = mLoadedApkField.get(application);
            Class<?> mLoadedApkClass = mLoadedApk.getClass();
            Field mActivityThreadField = mLoadedApkClass.getDeclaredField("mActivityThread");
            mActivityThreadField.setAccessible(true);
            Object mActivityThread = mActivityThreadField.get(mLoadedApk);
            Class<?> mActivityThreadClass = mActivityThread.getClass();
            Field mActivitiesField = mActivityThreadClass.getDeclaredField("mActivities");
            mActivitiesField.setAccessible(true);
            Object mActivities = mActivitiesField.get(mActivityThread);
            // 注意这里一定写成Map，低版本这里用的是HashMap，高版本用的是ArrayMap
            if (mActivities instanceof Map) {
                @SuppressWarnings("unchecked")
                Map<Object, Object> arrayMap = (Map<Object, Object>) mActivities;
                for (Map.Entry<Object, Object> entry : arrayMap.entrySet()) {
                    Object value = entry.getValue();
                    Class<?> activityClientRecordClass = value.getClass();
                    Field activityField = activityClientRecordClass.getDeclaredField("activity");
                    activityField.setAccessible(true);
                    Object o = activityField.get(value);
                    list.add((Activity) o);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            list = null;
        }
        return list;
    }