先看看效果
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</div>
看样子很不错把。下面我们来进行实现：
在RecyclerView中，为我们提供了ItemTouchHelper这么一个类来帮助我们实现这个功能。我们先来看看这个类给我们的注释把：
- This is a utility class to add swipe to dismiss and drag & drop support to RecyclerView.
- <p>
- It works with a RecyclerView and a Callback class, which configures what type of interactions
- are enabled and also receives events when user performs these actions.
- <p>
- Depending on which functionality you support, you should override
- {@link Callback#onMove(RecyclerView, ViewHolder, ViewHolder)} and / or
- {@link Callback#onSwiped(ViewHolder, int)}.
- <p>
- This class is designed to work with any LayoutManager but for certain situations, it can be
- optimized for your custom LayoutManager by extending methods in the
- {@link ItemTouchHelper.Callback} class or implementing {@link ItemTouchHelper.ViewDropHandler}
- interface in your LayoutManager.
- <p>
- By default, ItemTouchHelper moves the items' translateX/Y properties to reposition them. On
- platforms older than Honeycomb, ItemTouchHelper uses canvas translations and View's visibility
- property to move items in response to touch events. You can customize these behaviors by
- overriding {@link Callback#onChildDraw(Canvas, RecyclerView, ViewHolder, float, float, int,
- boolean)}
- or {@link Callback#onChildDrawOver(Canvas, RecyclerView, ViewHolder, float, float, int,
- boolean)}.
- <p/>
- Most of the time, you only need to override <code>onChildDraw</code> but due to limitations of
- platform prior to Honeycomb, you may need to implement <code>onChildDrawOver</code> as well.
这个注释写的已经很明白了，这个类就是就是帮助我们添加滑动和删除效果到RecyclerView中的。我们只需要继承CallBack，然后实现 {@link Callback#onMove(RecyclerView, ViewHolder, ViewHolder)} and / or{@link Callback#onSwiped(ViewHolder, int)}.
这两个方法就可以了。下面是具体实现过程。
public class MyItemTouchHelpCallback extends ItemTouchHelper.Callback {
/**Item操作的回调*/
private OnItemTouchCallbackListener onItemTouchCallbackListener;
/**是否可以拖拽**/
private boolean isCanDrag = false;
/***是否可以滑动*/
private boolean isCanSwipe = false;
public MyItemTouchHelpCallback(OnItemTouchCallbackListener onItemTouchCallbackListener) {
this.onItemTouchCallbackListener = onItemTouchCallbackListener;
}
public void setOnItemTouchCallbackListener(OnItemTouchCallbackListener onItemTouchCallbackListener){
this.onItemTouchCallbackListener = onItemTouchCallbackListener;
}
/**
* 设置是否可以被拖拽
* */
public void setDragEnable(boolean CanDrag){
this.isCanDrag = CanDrag;
}
/**
* 设置是否可以滑动
* @param canSwipe
*/
public void setSwipeEnable(boolean canSwipe){
this.isCanSwipe = canSwipe;
}
/**
* 当Item被长安的时候是否可以拖动
* @return
*/
@Override
public boolean isLongPressDragEnabled() {
return isCanDrag;
}
/**
* Item是否可以被滑动(H：左右滑动，V：上下滑动)
* @return
*/
@Override
public boolean isItemViewSwipeEnabled() {
return isCanSwipe;
}
/**
* 当用户拖拽或者滑动Item的时候需要我们告诉系统滑动或者拖拽的方向
* @param recyclerView
* @param viewHolder
* @return
*/
@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if(layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
int orientation = linearLayoutManager.getOrientation();
int dragFlag = 0;
int swipFlag = 0;
if(orientation== LinearLayoutManager.HORIZONTAL){
swipFlag = ItemTouchHelper.UP |ItemTouchHelper.DOWN;
dragFlag = ItemTouchHelper.LEFT |ItemTouchHelper.RIGHT;
}else if(orientation== LinearLayoutManager.VERTICAL){
dragFlag = ItemTouchHelper.UP |ItemTouchHelper.DOWN;
swipFlag = ItemTouchHelper.LEFT |ItemTouchHelper.RIGHT;
}
return makeMovementFlags(dragFlag,swipFlag);
}
return 0;
}
/**
* 当Item被拖拽的时候回调
* @param recyclerView
* @param viewHolder 拖拽的vieholder
* @param target 目的拖拽viewHolder
* @return
*/
@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
if(onItemTouchCallbackListener!=null)
return onItemTouchCallbackListener.onMove(viewHolder.getAdapterPosition(),target.getAdapterPosition());
return false;
}
/**
* 当Item被删除的时候回调
* @param viewHolder 要删除的item
* @param direction
*/
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
if(onItemTouchCallbackListener!=null){
onItemTouchCallbackListener.onSwiped(viewHolder.getAdapterPosition());
}
}
public interface OnItemTouchCallbackListener{
/**
* 当某个item被滑动删除的时候
* @param position
*/
void onSwiped(int position);
/**
* 当连个Item位置互相的时候
* @param srcPosition
* @param targerPostion
* @return
*/
boolean onMove(int srcPosition,int targerPostion);
}
}
上面的代码添加了不少的注释，相信理解起来很简单。
然后，在MainActivity中就可以进行调用了，但是为了方便起见，我们还是将其封装一次。
帮助类可以这么写：
public class MyItemTouchHelper extends YolandaItemTouchHelper {
private MyItemTouchHelpCallback myItemTouchHelpCallback;
public MyItemTouchHelper(MyItemTouchHelpCallback.OnItemTouchCallbackListener callback) {
super(new MyItemTouchHelpCallback(callback));
myItemTouchHelpCallback = (MyItemTouchHelpCallback) getCallback();
}
/**
* 设置是否可以拖动
* @param canDrag
*/
public void setDragEnable(boolean canDrag){
myItemTouchHelpCallback.setDragEnable(canDrag);
}
public void setSwipeEnable(boolean canSwipe){
myItemTouchHelpCallback.setSwipeEnable(canSwipe);
}
对了，为了方便获取到CallBack()，我们在新建了android.support.v7.widget.helper包，然后在该包下新建了
一个类YolandaItemTouchHelper，代码如下：
public class YolandaItemTouchHelper extends ItemTouchHelper {
/**
* Creates an ItemTouchHelper that will work with the given Callback.
* <p>
* You can attach ItemTouchHelper to a RecyclerView via
* {@link #attachToRecyclerView(RecyclerView)}. Upon attaching, it will add an item decoration,
* an onItemTouchListener and a Child attach / detach listener to the RecyclerView.
*
* @param callback The Callback which controls the behavior of this touch helper.
*/
public YolandaItemTouchHelper(Callback callback) {
super(callback);
}
public Callback getCallback(){
return mCallback;//返回了CallBack
}
}
最后，在MainActivity中进行调用就非常的简单了：代码如下：
itemTouchHelper = new MyItemTouchHelper(onItemTouchCallbackListener);
itemTouchHelper.attachToRecyclerView(mRecyclerView);
itemTouchHelper.setSwipeEnable(true);
itemTouchHelper.setDragEnable(true);
当然，onItemTouchCallbackListener也是很重要的，这里我们还需要先申明：
private MyItemTouchHelpCallback.OnItemTouchCallbackListener onItemTouchCallbackListener = new MyItemTouchHelpCallback.OnItemTouchCallbackListener(){
@Override
public void onSwiped(int position) {
if(datas !=null){
datas.remove(position);
adpater.notifyItemRemoved(position);
}
}
@Override
public boolean onMove(int srcPosition, int targerPostion) {
if(datas != null){
Collections.swap(datas,srcPosition,targerPostion);
adpater.notifyItemMoved(srcPosition,targerPostion);
}
return true;
}
};
大功告成！赶快去试试把~
