android Activity中几个关于栈的方法

悠悠 2024-04-17 06:19 33阅读 0赞

我们都知道Activity是放入任务栈中的，这里记录几个关于栈的方法，可能在某些业务中能用得上。

**1、**

/**
         * Return the identifier of the task this activity is in.  This identifier
         * will remain the same for the lifetime of the activity.
         *
         * @return Task identifier, an opaque integer.
         */
        public int getTaskId() {
            try {
                return ActivityTaskManager.getService().getTaskForActivity(mToken, false);
            } catch (RemoteException e) {
                return -1;
            }
        }

返回该Activity实例所在任务栈id，一般情况下，启动的多个Activity实例都在一个任务栈中，id也是一样的；

**2、**

/**
         * Return whether this activity is the root of a task.  The root is the
         * first activity in a task.
         *
         * @return True if this is the root activity, else false.
         */
        public boolean isTaskRoot() {
            return mWindowControllerCallback.isTaskRoot();
        }

返回该Activity实例是否在任务栈底;

**3、**

/**
         * Indication of whether this is the highest level activity in this task. Can be used to
         * determine whether an activity launched by this activity was placed in the same task or
         * another task.
         *
         * @return true if this is the topmost, non-finishing activity in its task.
         */
        final boolean isTopOfTask() {
            if (mToken == null || mWindow == null) {
                return false;
            }
            try {
                return ActivityTaskManager.getService().isTopOfTask(getActivityToken());
            } catch (RemoteException e) {
                return false;
            }
        }

返回该Activity实例是否处于任务栈的顶端；

**4、**

/**
         * Call this when your activity is done and should be closed and the task should be completely
         * removed as a part of finishing the root activity of the task.
         */
        public void finishAndRemoveTask() {
            finish(FINISH_TASK_WITH_ROOT_ACTIVITY);
        }

关闭该Activity实例以及所在任务栈，该Activity实例必须在栈底时才生效；

**5、**

/**
         * Move the task containing this activity to the back of the activity
         * stack.  The activity's order within the task is unchanged.
         *
         * @param nonRoot If false then this only works if the activity is the root
         *                of a task; if true it will work for any activity in
         *                a task.
         *
         * @return If the task was moved (or it was already at the
         *         back) true is returned, else false.
         */
        public boolean moveTaskToBack(boolean nonRoot) {
            try {
                return ActivityTaskManager.getService().moveActivityTaskToBack(mToken, nonRoot);
            } catch (RemoteException e) {
                // Empty
            }
            return false;
        }

这个方法很神奇，移动该Activity实例所在的任务栈到后台（到该系统所有Activity任务栈之后），不会调用 onDestroy()方法，就相当于是人为的点下了home键切换到了桌面；

**nonRoot：**

此参数为false，只有该处于任务栈底时才生效，为true，对于该栈所有Activity都有效，有个疑问，如果都有效直接true好了，搞个false不是多此一举吗？难道是为了性能更好的选择？

如果移动成功，返回true，失败返回false;

**6、**

/**
         * Sets information describing the task with this activity for presentation inside the Recents
         * System UI. When {@link ActivityManager#getRecentTasks} is called, the activities of each task
         * are traversed in order from the topmost activity to the bottommost. The traversal continues
         * for each property until a suitable value is found. For each task the taskDescription will be
         * returned in {@link android.app.ActivityManager.TaskDescription}.
         *
         * @see ActivityManager#getRecentTasks
         * @see android.app.ActivityManager.TaskDescription
         *
         * @param taskDescription The TaskDescription properties that describe the task with this activity
         */
        public void setTaskDescription(ActivityManager.TaskDescription taskDescription) {
            if (mTaskDescription != taskDescription) {
                mTaskDescription.copyFromPreserveHiddenFields(taskDescription);
                // Scale the icon down to something reasonable if it is provided
                if (taskDescription.getIconFilename() == null && taskDescription.getIcon() != null) {
                    final int size = ActivityManager.getLauncherLargeIconSizeInner(this);
                    final Bitmap icon = Bitmap.createScaledBitmap(taskDescription.getIcon(), size, size,
                            true);
                    mTaskDescription.setIcon(Icon.createWithBitmap(icon));
                }
            }
            try {
                ActivityTaskManager.getService().setTaskDescription(mToken, mTaskDescription);
            } catch (RemoteException e) {
            }
        }

设置手机任务列表界面中，该Activity实例任务栈的样式，比如：标题，图标，背景色等等；

好了，又可以愉快玩耍了。

[android activity启动模式\_Alex老夫子的博客-CSDN博客][android activity_Alex_-CSDN]

[android activity_Alex_-CSDN]: https://blog.csdn.net/msn465780/article/details/127185744?spm=1001.2014.3001.5502