Android 适配器模式应用及设计原理

 <android.support.v7.widget.RecyclerView
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:id="@+id/mrecycler"/>
  

  RecyclerView mrecycler= (RecyclerView) findViewById(R.id.mrecycler);
   mrecycler.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));

public static abstract class Adapter<VH extends ViewHolder> {

 private final AdapterDataObservable mObservable = new AdapterDataObservable();

 public abstract VH onCreateViewHolder(ViewGroup parent, int viewType);

 public abstract void onBindViewHolder(VH holder, int position);

 public void onBindViewHolder(VH holder, int position, List<Object> payloads) {
   onBindViewHolder(holder, position);
 }

 /**
  * This method calls {@link #onCreateViewHolder(ViewGroup, int)} to create a new
  * {@link ViewHolder} and initializes some private fields to be used by RecyclerView.
  *
  * @see #onCreateViewHolder(ViewGroup, int)
  */
 public final VH createViewHolder(ViewGroup parent, int viewType) {
   TraceCompat.beginSection(TRACE_CREATE_VIEW_TAG);
   final VH holder = onCreateViewHolder(parent, viewType);
   holder.mItemViewType = viewType;
   TraceCompat.endSection();
   return holder;
 }

 /**
  * This method internally calls {@link #onBindViewHolder(ViewHolder, int)} to update the
  * {@link ViewHolder} contents with the item at the given position and also sets up some
  * private fields to be used by RecyclerView.
  *
  * @see #onBindViewHolder(ViewHolder, int)
  */
 public final void bindViewHolder(VH holder, int position) {
   holder.mPosition = position;
   if (hasStableIds()) {
     holder.mItemId = getItemId(position);
   }
   holder.setFlags(ViewHolder.FLAG_BOUND,
       ViewHolder.FLAG_BOUND | ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID
           | ViewHolder.FLAG_ADAPTER_POSITION_UNKNOWN);
   TraceCompat.beginSection(TRACE_BIND_VIEW_TAG);
   onBindViewHolder(holder, position, holder.getUnmodifiedPayloads());
   holder.clearPayload();
   TraceCompat.endSection();
 }

 /**
  * Return the view type of the item at <code>position</code> for the purposes
  * of view recycling.
  *
  * <p>The default implementation of this method returns 0, making the assumption of
  * a single view type for the adapter. Unlike ListView adapters, types need not
  * be contiguous. Consider using id resources to uniquely identify item view types.
  *
  * @param position position to query
  * @return integer value identifying the type of the view needed to represent the item at
  *         <code>position</code>. Type codes need not be contiguous.
  */
 public int getItemViewType(int position) {
   return 0;
 }

 /**
  * Returns the total number of items in the data set hold by the adapter.
  *
  * @return The total number of items in this adapter.
  */
 public abstract int getItemCount();

 /**
  * Called when a view created by this adapter has been attached to a window.
  *
  * <p>This can be used as a reasonable signal that the view is about to be seen
  * by the user. If the adapter previously freed any resources in
  * {@link #onViewDetachedFromWindow(RecyclerView.ViewHolder) onViewDetachedFromWindow}
  * those resources should be restored here.</p>
  *
  * @param holder Holder of the view being attached
  */
 public void onViewAttachedToWindow(VH holder) {
 }

 /**
  * Called when a view created by this adapter has been detached from its window.
  *
  * <p>Becoming detached from the window is not necessarily a permanent condition;
  * the consumer of an Adapter's views may choose to cache views offscreen while they
  * are not visible, attaching an detaching them as appropriate.</p>
  *
  * @param holder Holder of the view being detached
  */
 public void onViewDetachedFromWindow(VH holder) {
 }

 /**
  * Register a new observer to listen for data changes.
  *
  * <p>The adapter may publish a variety of events describing specific changes.
  * Not all adapters may support all change types and some may fall back to a generic
  * {@link android.support.v7.widget.RecyclerView.AdapterDataObserver#onChanged()
  * "something changed"} event if more specific data is not available.</p>
  *
  * <p>Components registering observers with an adapter are responsible for
  * {@link #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver)
  * unregistering} those observers when finished.</p>
  *
  * @param observer Observer to register
  *
  * @see #unregisterAdapterDataObserver(RecyclerView.AdapterDataObserver)
  */
 public void registerAdapterDataObserver(AdapterDataObserver observer) {
   mObservable.registerObserver(observer);
 }

 /**
  * Unregister an observer currently listening for data changes.
  *
  * <p>The unregistered observer will no longer receive events about changes
  * to the adapter.</p>
  *
  * @param observer Observer to unregister
  *
  * @see #registerAdapterDataObserver(RecyclerView.AdapterDataObserver)
  */
 public void unregisterAdapterDataObserver(AdapterDataObserver observer) {
   mObservable.unregisterObserver(observer);
 }

 /**
  * Called by RecyclerView when it starts observing this Adapter.
  * <p>
  * Keep in mind that same adapter may be observed by multiple RecyclerViews.
  *
  * @param recyclerView The RecyclerView instance which started observing this adapter.
  * @see #onDetachedFromRecyclerView(RecyclerView)
  */
 public void onAttachedToRecyclerView(RecyclerView recyclerView) {
 }

 /**
  * Called by RecyclerView when it stops observing this Adapter.
  *
  * @param recyclerView The RecyclerView instance which stopped observing this adapter.
  * @see #onAttachedToRecyclerView(RecyclerView)
  */
 public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
 }

 /**
  * Notify any registered observers that the data set has changed.
  */
 public final void notifyDataSetChanged() {
   mObservable.notifyChanged();
 }

 /**
  * Notify any registered observers that the item at <code>position</code> has changed.
  * Equivalent to calling <code>notifyItemChanged(position, null);</code>.
  *
  * <p>This is an item change event, not a structural change event. It indicates that any
  * reflection of the data at <code>position</code> is out of date and should be updated.
  * The item at <code>position</code> retains the same identity.</p>
  *
  * @param position Position of the item that has changed
  *
  * @see #notifyItemRangeChanged(int, int)
  */
 public final void notifyItemChanged(int position) {
   mObservable.notifyItemRangeChanged(position, 1);
 }

 /**
  * Notify any registered observers that the item reflected at <code>fromPosition</code>
  * has been moved to <code>toPosition</code>.
  *
  * <p>This is a structural change event. Representations of other existing items in the
  * data set are still considered up to date and will not be rebound, though their
  * positions may be altered.</p>
  *
  * @param fromPosition Previous position of the item.
  * @param toPosition New position of the item.
  */
 public final void notifyItemMoved(int fromPosition, int toPosition) {
   mObservable.notifyItemMoved(fromPosition, toPosition);
 }
}

//根据需求，创建自定义样式的itemViw
 @Override
 public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
   View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item,viewGroup,false);
   ViewHolder vh = new ViewHolder(view);
   return vh;
 }

 //将数据与界面进行绑定的操作
 @Override
 public void onBindViewHolder(ViewHolder viewHolder, int position) {
   viewHolder.mTextView.setText(datas[position]);
 }

//获取数据的数量
 @Override
 public int getItemCount() {
   return datas.length;
 }

 public interface OnItemClickListener {
    void ItemClickListener(View view,int postion);
    void ItemLongClickListener(View view,int postion);

  }

  if(mListener!=null){//如果设置了监听那么它就不为空，然后回调相应的方法
      holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
          int pos = holder.getLayoutPosition();//得到当前点击item的位置pos
          mListener.ItemClickListener(holder.itemView,pos);//把事件交给我们实现的接口那里处理
        }
      });
      holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View v) {
          int pos = holder.getLayoutPosition();//得到当前点击item的位置pos
          mListener.ItemLongClickListener(holder.itemView,pos);//把事件交给我们实现的接口那里处理
          return true;
        }
      });
    }

  adapter=new MyRecyclerAdapter(this, list);
   mrecycler.setAdapter(adapter);
   adapter.setOnclickListener(new MyRecyclerAdapter.OnItemClickListener() {
     @Override
     public void ItemClickListener(View view, int postion) {
       Toast.makeText(MainActivity.this,"点击了："+postion, Toast.LENGTH_SHORT).show();
     }

     @Override
     public void ItemLongClickListener(View view, int postion) {
       list.remove(postion);
       adapter.notifyItemRemoved(postion);
     }
   });