android中用任务栈的方式获取到activity的上下文

可以使用以下代码获取到当前任务栈的顶层Activity的上下文：

Context context = getApplicationContext();
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> runningTasks = activityManager.getRunningTasks(1);
ActivityManager.RunningTaskInfo runningTaskInfo = runningTasks.get(0);
ComponentName topActivity = runningTaskInfo.topActivity;
Context topActivityContext = null;
try {
    topActivityContext = context.createPackageContext(topActivity.getPackageName(), Context.CONTEXT_IGNORE_SECURITY | Context.CONTEXT_INCLUDE_CODE);
} catch (PackageManager.NameNotFoundException e) {
    e.printStackTrace();
}

其中，topActivityContext即为当前任务栈的顶层Activity的上下文。需要注意的是，这种方式会涉及到跨进程的内存共享，需要注意安全性问题。