androidlistview滑动事件,AndroidListView监听滑动事件的方法

ListView的主要有两种滑动事件监听方法&＃xff0c;OnTouchListener和OnScrollListener

1.OnTouchListener

OnTouchListener方法来自View中的监听事件&＃xff0c;可以在监听三个Action事件发生时通过MotionEvent的getX()方法或getY()方法获取到当前触摸的坐标值&＃xff0c;来对用户的滑动方向进行判断&＃xff0c;并可在不同的Action状态中做出相应的处理

mListView.setOnTouchListener(new View.OnTouchListener() {

&＃64;Override

public boolean onTouch(View v, MotionEvent event) {

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

// 触摸按下时的操作

break;

case MotionEvent.ACTION_MOVE:

// 触摸移动时的操作

break;

case MotionEvent.ACTION_UP:

// 触摸抬起时的操作

break;

}

return false;

}

});

不仅仅只有上面的三种Action状态&＃xff0c;MotionEvent类中还定义了很多其它状态&＃xff0c;我们可以灵活的使用这些状态

MotionEvent.ACTION_DOWN&＃xff1a;开始触摸

MotionEvent.ACTION_MOVE&＃xff1a;触摸移动

MotionEvent.ACTION_UP&＃xff1a;触摸抬起

MotionEvent.ACTION_OUTSIDE&＃xff1a;触摸范围超过了UI边界

MotionEvent.ACTION_POINTER_DOWN&＃xff1a;当有另外一个触摸按下时(多点触摸)

MotionEvent.ACTION_POINTER_UP&＃xff1a;当另一个触摸抬起时(多点触摸)

2.OnScrollListener

OnScrollListener来自AbsListView中的监听事件&＃xff0c;因为ListView直接继承自AbsListView&＃xff0c;所以在AbsListView中有很多ListView相关信息

OnScrollListener中有两个回调方法

public void onScrollStateChanged(AbsListView view, int scrollState)&＃xff1a;监听滑动状态的改变

public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)&＃xff1a;监听滑动

在源码中有其详细的解释

/** * Interface definition for a callback to be invoked when the list or grid * has been scrolled. */

public interface OnScrollListener {

/** * The view is not scrolling. Note navigating the list using the trackball counts as * being in the idle state since these transitions are not animated. */

public static int SCROLL_STATE_IDLE &＃61; 0;

/** * The user is scrolling using touch, and their finger is still on the screen */

public static int SCROLL_STATE_TOUCH_SCROLL &＃61; 1;

/** * The user had previously been scrolling using touch and had performed a fling. The * animation is now coasting to a stop */

public static int SCROLL_STATE_FLING &＃61; 2;

/** * Callback method to be invoked while the list view or grid view is being scrolled. If the * view is being scrolled, this method will be called before the next frame of the scroll is * rendered. In particular, it will be called before any calls to * {&＃64;link Adapter#getView(int, View, ViewGroup)}. * *&＃64;param view The view whose scroll state is being reported * *&＃64;param scrollState The current scroll state. One of * {&＃64;link #SCROLL_STATE_TOUCH_SCROLL} or {&＃64;link #SCROLL_STATE_IDLE}. */

public void onScrollStateChanged(AbsListView view, int scrollState);

/** * Callback method to be invoked when the list or grid has been scrolled. This will be * called after the scroll has completed *&＃64;param view The view whose scroll state is being reported *&＃64;param firstVisibleItem the index of the first visible cell (ignore if * visibleItemCount &＃61;&＃61; 0) *&＃64;param visibleItemCount the number of visible cells *&＃64;param totalItemCount the number of items in the list adaptor */

public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,

int totalItemCount);

}

2.1 OnScrollSateChanged方法

OnScrollSateChanged根据scrollState来决定其回调的次数&＃xff0c;它有三种模式&＃xff1a;

OnScrollListener.SCROLL_STATE_IDLE&＃xff1a;滚动停止时的状态

OnScrollListener.SCROLL_STATE_STOUCH_SCROLL&＃xff1a;触摸正在滚动&＃xff0c;手指还没离开界面时的状态

OnScrollListener.SCROLL_STATE_FLING&＃xff1a;用户在用力滑动后&＃xff0c;ListView由于惯性将继续滑动时的状态

当用户没有用力滑动时&＃xff0c;OnScrollSateChanged方法只会回调2次&＃xff0c;否则回调三次&＃xff0c;我们在使用时通常会以设置Flag标志&＃xff0c;来区分不同的滑动状态&＃xff0c;从而进行相应的处理

2.2 OnScroll方法

在ListView滚动时会一直被回调&＃xff0c;它通过里面有三个参数来显示当前ListView的滚动状态

firstVisibleItem&＃xff1a;当前能看见的第一个item的ID(从0开始)

visibleItemCount&＃xff1a;当前可见的item总数

totalItemCount&＃xff1a;列表中适配器总数量&＃xff0c;也就是整个ListView中item总数

注意&＃xff1a;当前可见的item总数&＃xff0c;包括屏幕中没有显示完整的item&＃xff0c;如显示一半的item也会算在可见范围内

通过这三个参数&＃xff0c;我么可以实现很多事件判断&＃xff0c;如&＃xff1a;

(1)判断当前是否滑动到最后一行

当前视图中第一个item的ID加上当前屏幕中可见item的总数如果等于ListView中所有item总数时&＃xff0c;就表示移动到了最后一行

if (firstVisibleItem &＃43; visibleItemCount &＃61;&＃61; totalItemCount && totalItemCount > 0) {

// 滚动到最后一行了

}

(2)判断滑动的方向

通过oldVisibleItem 记录上一次firstVisibleItem的位置&＃xff0c;再与滑动后的firstVisibleItem进行比较&＃xff0c;就可得知滑动的方向

if (firstVisibleItem > oldVisibleItem) {

// 向上滑动

}

if (firstVisibleItem

// 向下滑动

}

oldVisibleItem &＃61; firstVisibleItem;

ListView也为我们提供了一些封装好了的方法&＃xff0c;来获取item的位置信息

// 获取当前可见区域内第一个item的id

mListView.getFirstVisiblePosition();

// 获取当前可见区域内最后一个item的id

mListView.getLastVisiblePosition();