Android中如何一次性finish掉以前打开的所有的activity

public class ActivityManagerApplication extends Application {

    private static Map<String,Activity> destoryMap = new HashMap<>();

    private ActivityManagerApplication() {
    }

    /**
     * 添加到销毁队列
     *
     * @param activity 要销毁的activity
     */

    public static void addDestoryActivity(Activity activity,String activityName) {
        destoryMap.put(activityName,activity);
    }
	/**
	*销毁指定Activity
	*/
    public static void destoryActivity(String activityName) {
       Set<String> keySet=destoryMap.keySet();
        for (String key:keySet){
            destoryMap.get(key).finish();
        }
    }
}