RecyclerView：带header&footer&加载更多

import java.util.ArrayList;
import java.util.List;

import com.example.test.R;
import com.widget.view.HeaderFooterAdapter.ViewHolder;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * 为了用RecyclerView创建一个带header的grid：

	1,定义一个具有两种view类型的adapter，一个为header一个为普通item。
	
	2,inflate一个header，把它传递给adapter。
	
	3,重写GridLayoutManager中的setSpanSizeLookup，在header所处的位置返回和span count（列数）相等的 span size。
 * @author Administrator
 *
 */
public class HeaderFooterAdapter extends RecyclerView.Adapter {

	private static final int ITEM_VIEW_TYPE_HEADER = 0;
	private static final int ITEM_VIEW_TYPE_ITEM = 1;
	private static final int ITEM_VIEW_TYPE_FOOTER = 2;

	private final View header;
	private final View footer;
	private int headerCount=0;
	private int footerCount=0;
	private final List beans;
	
	public HeaderFooterAdapter(View header, View footer,List beans) {
		headerCount=header == null?0:1;
		footerCount=footer == null?0:1;
		this.header = header;
		this.footer = footer;
		this.beans = beans;
	}

	public boolean isHeader(int position) {
		if(headerCount==0){
			return false;
		}
		return position == 0;
	}
	public boolean isFooter(int position) {
		if(footerCount==0){
			return false;
		}
		return position == beans.size()+headerCount;// add 1 for footer
//		return position == getItemCount()-headerCount;// or Subtract 1 for footer
	}

	@Override
	public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
		if (viewType == ITEM_VIEW_TYPE_HEADER) {
			return new ViewHolder(header);
		}
		if (viewType == ITEM_VIEW_TYPE_FOOTER) {
			return new ViewHolder(footer);
		}
		View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false);
		return new ViewHolder(view);
	}

	@Override
	public void onBindViewHolder(final ViewHolder holder, final int position) {
		if (isHeader(position)) {
			return;
		}
		if (isFooter(position)) {
			return;
		}
		final T bean = beans.get(position - headerCount); // Subtract 1 for header
		holder.textView.setText(bean.toString());
	}

	@Override
	public int getItemViewType(int position) {
		if(isHeader(position)){
			return ITEM_VIEW_TYPE_HEADER;
		}
		if(isFooter(position)){
			return ITEM_VIEW_TYPE_FOOTER;
		}
		return ITEM_VIEW_TYPE_ITEM;
	}

	/**
	 * 获得实际View的数量，包括header和footer
	 */
	@Override
	public int getItemCount() {
		return beans.size() + headerCount+footerCount;
	}

	class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener,View.OnLongClickListener{
		public TextView textView;

		public ViewHolder(View itemView) {
			super(itemView);
			if (onItemClickLitener != null){
				itemView.setOnClickListener(this);
            }
			if(onItemLongClickLitener!=null){
				itemView.setOnLongClickListener(this);
            }
			textView = (TextView) itemView.findViewById(R.id.item_0);
		}

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			onItemClickLitener.onItemClick(v, getLayoutPosition());//getPosition()被废弃了
		}
		
		@Override
		public boolean onLongClick(View v) {
			// TODO Auto-generated method stub
			onItemLongClickLitener.onItemLongClick(v, getLayoutPosition());
			return true;
		}
		
	}
	
	private static OnItemClickLitener onItemClickLitener;
	
	public void setOnItemClickLitener(OnItemClickLitener onItemClickLitener) {
		this.onItemClickLitener = onItemClickLitener;
	}
	
	public interface OnItemClickLitener {
		/**
		 * 点击回调，注意position，指的是在Adapter中的位置，已经算上header
		 * @param view
		 * @param position
		 */
		void onItemClick(View view, int position);
	}

	private static OnItemLongClickLitener onItemLongClickLitener;
	
	public void setOnItemLongClickLitener(OnItemLongClickLitener onItemLongClickLitener) {
		this.onItemLongClickLitener = onItemLongClickLitener;
	}

	public interface OnItemLongClickLitener {
		/**
		 * 长按回调，注意position，指的是在Adapter中的位置，已经算上header
		 * @param view
		 * @param position
		 */
		void onItemLongClick(View view, int position);
	}
	
	/**
	 * 在position位置插入item
	 * @param position:指的是item在beans中的位置，而不是在Adapter中的位置；
	 * 所以在notifyItemInserted的时候需要算上header
	 * @param item
	 */
	public void addItemAt(int position,T item) {
		beans.add(position, item);
        notifyItemInserted(position+headerCount);
    }
	/**
	 * 在底部添加Items
	 * @param items
	 */
	public void addItemsAtLast(ArrayList items) {
		int size=beans.size();
		beans.addAll(items);
		notifyItemRangeInserted(size+headerCount, items.size());
	}

	/**
	 * 移除position位置的Item
	 * @param position :指的是item在beans中的位置，而不是在Adapter中的位置；
	 * 所以在notifyItemInserted的时候需要算上header
	 */
	public void removeItemAt(int position) {
		beans.remove(position);
        notifyItemRemoved(position+headerCount);
    }
	
	/**
	 * 获得中间Item的数量，不包括header和footer
	 * @return
	 */
	public int getItemSize(){
		return beans.size();
	}
	
}

ArrayList list=new ArrayList();
    		for (int i = 0; i  adapter = new HeaderFooterAdapter(header,footer, list);
			adapter.setOnItemClickLitener(new HeaderFooterAdapter.OnItemClickLitener() {
				
				@Override
				public void onItemClick(View view, int position) {
					// TODO Auto-generated method stub
					if(adapter.isHeader(position)){
						Toast.makeText(context, "header clicked", Toast.LENGTH_SHORT).show();
					}else if(adapter.isFooter(position)){
						Toast.makeText(context, "footer clicked", Toast.LENGTH_SHORT).show();
					}else{
						Toast.makeText(context, "header item "+position, Toast.LENGTH_SHORT).show();
					}
				}
			});
			
        	final GridLayoutManager manager = new GridLayoutManager(this, 2);
        	manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
				@Override
				public int getSpanSize(int position) {
					if(adapter.isHeader(position)||adapter.isFooter(position)){
						return manager.getSpanCount();
					}
					return  1;
				}
			});
        	//如果可以确定每个item的高度是固定的，设置这个选项可以提高性能
        	recyclerView.setHasFixedSize(true);
        	recyclerView.setLayoutManager(manager);
			recyclerView.setAdapter(adapter);
			recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
				@Override 
				public void onScrolled(RecyclerView rv, int dx, int dy) {
	                boolean isBottom =
	                		manager.findLastCompletelyVisibleItemPosition()>= adapter.getItemCount()-1;
	                if (isBottom) {
	                	ArrayList list=new ArrayList();
	                	int size=adapter.getItemSize();
	            		for (int i = size; i