对于android开发者来说RecyclerView应该已经很熟悉了，项目中基本都是使用RecyclerView来实现列表效果，这里要实现的是RecyclerView的条目拖拽、左滑、右滑移除效果，这些效果都是在RecyclerView列表基础上来实现的，所以还是先简单的实现RecyclerView的列表效果；
一开始肯定要引入依赖库：
compile 'com.android.support:recyclerview-v7:25.3.1'
接下来在xml布局文件中使用同时通过findViewById在activity文件中引入；
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"xmlns:tools="/tools"android:id="@+id/activity_main"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context="com.qqrecyclerview.MainActivity"><android.support.v7.widget.RecyclerViewandroid:id="@+id/recycler_view"android:layout_width="match_parent"android:layout_height="match_parent"/></LinearLayout>
public class MainActivity extends AppCompatActivity{private RecyclerView recyclerView;private MessageAdapter adapter;private ItemTouchHelper itemTouchHelper;private List<String> list;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);list = DataUtils.getData();recyclerView = (RecyclerView) findViewById(R.id.recycler_view);//设置布局管理器recyclerView.setLayoutManager(new LinearLayoutManager(this));//设置适配器adapter = new MessageAdapter(this, list, this);recyclerView.setAdapter(adapter); adapter.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClickListener(int position) {Toast.makeText(MainActivity.this, list.get(position), Toast.LENGTH_LONG).show();}});}}
这里关键在与适配器了；
package com.qqrecyclerview;import android.content.Context;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.TextView;import java.util.Collections;import java.util.List;/*** Created by Administrator on /12/25.*/public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageHolder>{private Context context;private List<String> list;private StartDragLinstener startDragLinstener;public MessageAdapter(Context context, List<String> list, StartDragLinstener startDragLinstener) {this.context = context;this.list = list;this.startDragLinstener = startDragLinstener;}@Overridepublic MessageHolder onCreateViewHolder(ViewGroup parent, int viewType) {View view = LayoutInflater.from(context).inflate(R.layout.message_item, parent, false);MessageHolder holder = new MessageHolder(view);return holder;}@Overridepublic void onBindViewHolder(final MessageHolder holder, final int position) {holder.tv.setText(list.get(position));holder.iv.setOnTouchListener(new View.OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {//传递事件if (event.getAction() == MotionEvent.ACTION_DOWN) {if (startDragLinstener != null) {startDragLinstener.onStartDrag(holder);}}//如果想拦截imageview的点击事件return true就可以了return false;}});/*** 条目点击*/holder.itemView.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {if(listener!=null){listener.onItemClickListener(position);}}});}@Overridepublic int getItemCount() {return list == null ? 0 : list.size();}class MessageHolder extends RecyclerView.ViewHolder {TextView tv;ImageView iv;public MessageHolder(View itemView) {super(itemView);tv = (TextView) itemView.findViewById(R.id.tv);iv = (ImageView) itemView.findViewById(R.id.iv);}}private OnItemClickListener listener;/*** 条目点击* @param listener*/public void setOnItemClickListener(OnItemClickListener listener){this.listener=listener;}}
RecyclerView的适配器和ListView的适配器有很大的不同，RecyclerView的适配器需要重写onCreateViewHolder(),onBindViewHolder(),getItemCount(),三个方法，通过每个方法的含义就能知道每个方法对应的功能实现，除此之外还要创建一个ViewHolder对象，不过RecyclerView并没实现条目的点击和长按等事件的处理，都知道RecyclerView只负责数据的加载和复用回收，这里利用接口回调的方式来实现条目点击的，长按等事件的实现也可仿照其实现；
/*** Created by Administrator on /12/26.* RecylerView条目点击*/public interface OnItemClickListener {void onItemClickListener(int position);}
普通列表效果就实现了，在上面的基础上慢慢的去实现条目拖拽和左滑、右滑等效果；
系统提供了ItemTouchHelper类可以轻松的实现条目拖拽和左滑、右滑等效果；在activity中先将ItemTouchHelper类和RecyclerView绑定关系；
//实例化ItemTouchHelperitemTouchHelper = new ItemTouchHelper(new MessageItemTouchCallBack(adapter));//将ItemTouchHelper和RecyclerView进行关联itemTouchHelper.attachToRecyclerView(recyclerView);
ItemTouchHelper实例化的时候需要传入一个Callback的抽象类，MessageItemTouchCallBack类是Callback的子类，在MessageItemTouchCallBack在构造方法中需要传入一个ItemTouchHelperAdapterCallBack接口，而MessageAdapter类实现了ItemTouchHelperAdapterCallBack接口，所以出入一个MessageAdapter就可以了；
public class MessageItemTouchCallBack extends ItemTouchHelper.Callback {private ItemTouchHelperAdapterCallBack adapterCallBack;public MessageItemTouchCallBack(ItemTouchHelperAdapterCallBack adapterCallBack) {this.adapterCallBack = adapterCallBack;}@Overridepublic int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {//callback回调监听哪些动作，判断方向(水平方向，垂直方向)//垂直方向int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;//水平方向int swipeFlags = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;return makeMovementFlags(dragFlags, swipeFlags);}@Overridepublic boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {//监听滑动(水平方向，垂直方向)//将集合中的两个数据进行位置交互//同时还要刷新RecyclerViewadapterCallBack.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());return false;}@Overridepublic void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {//滑动删除的动作的时候回调//删除数据集合里面的direction位置的数据//刷新adapteradapterCallBack.onItemSwiped(viewHolder, viewHolder.getAdapterPosition());}@Overridepublic boolean isLongPressDragEnabled() {//长按拖动是否打开return true;}@Overridepublic void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {//实现动画//侧滑动作if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {swipedItem(dX, viewHolder);}super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);}/*** 添加侧滑删除动作动画效果** @param dX* @param viewHolder*/private void swipedItem(float dX, RecyclerView.ViewHolder viewHolder) {float alpha = 1 - Math.abs(dX) / viewHolder.itemView.getWidth();//透明度动画viewHolder.itemView.setAlpha(alpha);//X缩放动画viewHolder.itemView.setScaleX(Math.max(0.6f, alpha));//Y缩放动画viewHolder.itemView.setScaleY(Math.max(0.6f, alpha));if (alpha == 0) {//代表滑出去了viewHolder.itemView.setAlpha(1);viewHolder.itemView.setScaleX(1);viewHolder.itemView.setScaleY(1);}}}
每个方法都做了说明，在这里拖拽或者移除时要将其回调到RecyclerView的适配器中，方便数据的处理；刚好 MessageAdapter类实现了 ItemTouchHelperAdapterCallBack接口，就会重写onItemMove和onItemSwiped方法；
/*** Created by Administrator on /12/26.*/public interface ItemTouchHelperAdapterCallBack {/*** 当拖拽的时候回调* @param fromPosition 开始触摸位置* @param toPosition 目标位置* @return*/boolean onItemMove(int fromPosition,int toPosition);/*** 左右滑动删除的时候回调* @param toPosition 滑动的位置*/void onItemSwiped(RecyclerView.ViewHolder holder,int toPosition);}
ItemTouchHelperAdapterCallBack接口提供的方法；
@Overridepublic boolean onItemMove(int fromPosition, int toPosition) {//将集合中的两个数据进行位置交互Collections.swap(list, fromPosition, toPosition);//同时还要刷新RecyclerViewnotifyItemMoved(fromPosition, toPosition);return false;}@Overridepublic void onItemSwiped(RecyclerView.ViewHolder holder, int toPosition) {//删除数据集合里面的direction位置的数据list.remove(toPosition);//刷新adapternotifyItemRemoved(toPosition);}
还有一个比较重要的就是在实例化adapter的时候传入一个StartDragLinstener接口；
/*** Created by Administrator on /12/26.*/public interface StartDragLinstener {void onStartDrag(RecyclerView.ViewHolder viewHolder);}
在重写onStartDrag方法的时候需要调用ItemTouchHelper中的startDrag方法，才能够去触发拖拽，移除等方法；
@Overridepublic void onStartDrag(RecyclerView.ViewHolder viewHolder) {//调用startDrag方法后就会去回调onSwiped()方法itemTouchHelper.startDrag(viewHolder);}
这样子就实现了一个比较简单的RecyclerView的条目拖拽、左滑、右滑移除效果了；源码地址： /s/1o9O6iyY
