为RecyclerView添加header和footer

作者: JC_Hou | 来源:发表于2016-11-24 13:58 被阅读923次

RecyclerView和各种LayoutManager都没有直接的方法添加header和footer，因此我们就需要思考如何为RecyclerView添加header和footer了。
这里我的解决方案和网上你能搜到的大多数方案一样，是通过控制Adapter的itemType来设置的，思路就是根据不同的itemType去加载不同的布局。

先po上完整代码

public class PubuAdapter extends RecyclerView.Adapter<PubuAdapter.PubuHolder> {
    public static final int TYPE_HEADER = 0; 
    public static final int TYPE_FOOTER = 1;  
    public static final int TYPE_NORMAL = 2;  

    private List<DataBean> mList;

    //HeaderView, FooterView
    private View mHeaderView;
    private View mFooterView;

    public PubuAdapter(List<DataBean> mList) {
        this.mList=mList;
    }

    public View getmHeaderView() {
        return mHeaderView;
    }

    public void setmHeaderView(View mHeaderView) {
        this.mHeaderView = mHeaderView;
        //shouweicharu
        notifyItemInserted(0);
    }

    public View getmFooterView() {
        return mFooterView;
    }

    public void setmFooterView(View mFooterView) {
        this.mFooterView = mFooterView;
        if (mHeaderView==null){
            notifyItemInserted(mList.size());
        }else {
            notifyItemInserted(mList.size()+1);
        }
    }

    @Override
    public int getItemViewType(int position) {
        if (mHeaderView==null){
            if (mFooterView==null){
                return TYPE_NORMAL;
            }else{
                if (position==mList.size()){
                    return TYPE_FOOTER;
                }else{
                    return TYPE_NORMAL;
                }
            }
        }else {
            if (position==0){
                return TYPE_HEADER;
            }else{
                if (mFooterView==null){
                    return TYPE_NORMAL;
                }else{
                    if (position!=mList.size()+1){
                        return TYPE_NORMAL;
                    }else{
                        return TYPE_FOOTER;
                    }
                }
            }
        }
    }

    @Override
    public PubuHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (mHeaderView!=null&&viewType==TYPE_HEADER){
            return new PubuHolder(mHeaderView);
        }else if (mFooterView!=null&&viewType==TYPE_FOOTER){
            return new PubuHolder(mFooterView);
        }
        return new PubuHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.recycle_item,parent,false));
    }

    @Override
    public void onBindViewHolder(PubuHolder holder, int position) {
        if (getItemViewType(position)==TYPE_HEADER||getItemViewType(position)==TYPE_FOOTER){
            return;
        }else if (getItemViewType(position)==TYPE_NORMAL){
            holder.imageView.setImageResource(mList.get(position-1).getImage());
            holder.textView.setText(mList.get(position-1).getText());
            //如果设置了回调，则设置点击事件
            final int realPosition = getRealPosition(holder);
            if(mOnItemClickListener!=null){
                holder.imageView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
//                        int pos=holder.getLayoutPosition();//布局真正的position，recyclerView进行添加，移除item时，会导致position位置变化
                        mOnItemClickListener.onItemClick(v,realPosition);
                    }
                });
                holder.imageView.setOnLongClickListener(new View.OnLongClickListener() {
                    @Override
                    public boolean onLongClick(View v) {
//                        int pos=holder.getLayoutPosition();//布局真正的position，recyclerView进行添加，移除item时，会导致position位置变化
                        mOnItemClickListener.onItemLongClick(v,realPosition);
                        return false;
                    }
                });
            }
        }
    }

//重写此方法，判断recyclerview的layoutmanager为GridLayoutManager的时候，是header和footer独占一行，而不是一个item
    @Override
    public void onAttachedToRecyclerView(final RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager){
            final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
                @Override
                public int getSpanSize(int position) {
                    return getItemViewType(position)==TYPE_HEADER||getItemViewType(position)==TYPE_FOOTER?gridLayoutManager.getSpanCount():1;
                }
            });
        }
    }

//重写此方法，判断recyclerview的layoutmanager为StaggeredGridLayoutManager的时候，是header和footer独占一行，而不是一个item
    @Override
    public void onViewAttachedToWindow(PubuHolder holder) {
        super.onViewAttachedToWindow(holder);
        ViewGroup.LayoutParams layoutParams = holder.itemView.getLayoutParams();
        if (layoutParams!=null&&layoutParams instanceof StaggeredGridLayoutManager.LayoutParams){
            StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) layoutParams;
            params.setFullSpan(getItemViewType(holder.getLayoutPosition())==TYPE_HEADER||getItemViewType(holder.getLayoutPosition())==TYPE_FOOTER);
        }
    }

//获取item的真实位置
    private int getRealPosition(RecyclerView.ViewHolder viewHolder){
        int layoutPosition = viewHolder.getLayoutPosition();
        return mHeaderView==null?layoutPosition:layoutPosition-1;
    }

    @Override
    public int getItemCount() {
        if (mHeaderView==null){
            if (mFooterView==null){
                return mList.size();
            }else {
                return mList.size()+1;
            }
        }else{
            if (mFooterView==null){
                return mList.size()+1;
            }else {
                return mList.size()+2;
            }
        }
    }

    class PubuHolder extends RecyclerView.ViewHolder{
        ImageView imageView;
        TextView textView;

        public PubuHolder(View itemView) {
            super(itemView);
            if (itemView==mHeaderView)return;
            imageView= (ImageView) itemView.findViewById(R.id.pubu_img);
            textView= (TextView) itemView.findViewById(R.id.pubu_txt);
        }
    }

    interface onItemClickListener{
        void onItemClick(View view, int position);
        void onItemLongClick(View view, int position);
    }

    private onItemClickListener mOnItemClickListener;

    public void setOnItemClickListener(onItemClickListener mOnItemClickListener) {
        this.mOnItemClickListener = mOnItemClickListener;
    }
}```

>这里我们重写了getItemViewType方法，并根据位置来返回不同的type，这个type是我们预先商定好的常量，接在onCreateViewHolder方法中来判断itemType，如果是header，则返回我们设置的headerView，如果是footer，则返回我们设置的footerView，否则正常加载item布局

Activity中的使用

    mRecycleView= (RecyclerView) findViewById(R.id.recycle_view);
    adapter=new PubuAdapter(mList);
    adapter.setOnItemClickListener(new PubuAdapter.onItemClickListener() {
        @Override
        public void onItemClick(View view, int position) {
            Toast.makeText(MainActivity.this,(position+1)+"click", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onItemLongClick(View view, int position) {
            Toast.makeText(MainActivity.this,(position+1)+"long click", Toast.LENGTH_SHORT).show();
            adapter.removeData(position);
        }
    });
    //先设置layoutmanager,再添加headre、footer
    mRecycleView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL,false));
    adapter.setmHeaderView(LayoutInflater.from(this).inflate(R.layout.header,mRecycleView,false));
    View footer = LayoutInflater.from(this).inflate(R.layout.footer, mRecycleView, false);
    adapter.setmFooterView(footer);
    mRecycleView.setAdapter(adapter);```

当使用GridLayoutManager和StaggeredGridLayoutManager的时候会出现header和footer占一个item而不是一行的问题，我们需要重写Adapter里面的两个方法来处理这个问题

//重写此方法，判断recyclerview的layoutmanager为GridLayoutManager的时候，是header和footer独占一行，而不是一个item
    @Override
    public void onAttachedToRecyclerView(final RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager){
            final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
                @Override
                public int getSpanSize(int position) {
                    return getItemViewType(position)==TYPE_HEADER||getItemViewType(position)==TYPE_FOOTER?gridLayoutManager.getSpanCount():1;
                }
            });
        }
    }

//重写此方法，判断recyclerview的layoutmanager为StaggeredGridLayoutManager的时候，是header和footer独占一行，而不是一个item
    @Override
    public void onViewAttachedToWindow(PubuHolder holder) {
        super.onViewAttachedToWindow(holder);
        ViewGroup.LayoutParams layoutParams = holder.itemView.getLayoutParams();
        if (layoutParams!=null&&layoutParams instanceof StaggeredGridLayoutManager.LayoutParams){
            StaggeredGridLayoutManager.LayoutParams params = (StaggeredGridLayoutManager.LayoutParams) layoutParams;
            params.setFullSpan(getItemViewType(holder.getLayoutPosition())==TYPE_HEADER||getItemViewType(holder.getLayoutPosition())==TYPE_FOOTER);
        }
    }```

效果如下


![StaggeredGridLayoutManager.png](http:https://img.haomeiwen.com/i1814117/5299fd2cd3850918.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)


![GridLayoutManager.png](https://img.haomeiwen.com/i1814117/2e2d45588ec68d4b.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

网友评论

899e2d74bdeb:@Override
public void onBindViewHolder(PubuHolder holder, int position) {
if (getItemViewType(position)==TYPE_HEADER||getItemViewType(position)==TYPE_FOOTER){
return;
}else if (getItemViewType(position)==TYPE_NORMAL){
holder.imageView.setImageResource(mList.get(position-1).getImage());
holder.textView.setText(mList.get(position-1).getText());
//如果设置了回调，则设置点击事件
final int realPosition = getRealPosition(holder);
if(mOnItemClickListener!=null){
holder.imageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// int pos=holder.getLayoutPosition();//布局真正的position，recyclerView进行添加，移除item时，会导致position位置变化
mOnItemClickListener.onItemClick(v,realPosition);
}
});
holder.imageView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
// int pos=holder.getLayoutPosition();//布局真正的position，recyclerView进行添加，移除item时，会导致position位置变化
mOnItemClickListener.onItemLongClick(v,realPosition);
return false;
}
});
}
}
}
这里还需要判断一下header存不存在，mList.get(position-1)才要减一
JC_Hou:@哎疯 final int realPosition = getRealPosition(holder);
private int getRealPosition(RecyclerView.ViewHolder viewHolder) {
int layoutPosition = viewHolder.getLayoutPosition();
return mHeaderView == null ? layoutPosition : layoutPosition - 1;
}
已经获取了真实position，可以直接使用，可以试一下
策马啸西风1214:学习了

本文标题：为RecyclerView添加header和footer

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