RecyclerView实现添加头部和底部

1、主要用到下面四个方法。

2、方法开源于 鸿洋_ 的这篇文章 Android 优雅的为RecyclerView添加HeaderView和FooterView

大神是通过类似装饰者模式，去设计一个类，在不改变原有的Adapter基础上去增强其功能，使其支持addHeaderView和addFooterView。

3、而此篇文章是直接对RecyclerView.Adapter动手，使其支持addHeaderView和addFooterView，removeHeaderView和removeFooterView。

4、原理大神已给出，直接代码。直接继承此adapter即可。

import java.util.List;import android.content.Context;import android.support.v4.util.SparseArrayCompat;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.view.View;import android.view.ViewGroup;import com.huahan.readerviewpager.adapter.ViewHolder;/** * Created by android.mtj on 2017/4/1. */public abstract class BaseRecyclerViewAdapter<T> extends        RecyclerView.Adapter<ViewHolder> {    private static final int BASE_ITEM_TYPE_HEADER = 100000;    private static final int BASE_ITEM_TYPE_FOOTER = 200000;    private SparseArrayCompat<View> mHeaderViews = new SparseArrayCompat<>();    private SparseArrayCompat<View> mFootViews = new SparseArrayCompat<>();    private Context context;    private List<T> list;    public BaseRecyclerViewAdapter(Context context, List<T> list) {        this.context = context;        this.list = list;    }    @Override    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        ViewHolder holder = null;        if (mHeaderViews.get(viewType) != null) {            holder = ViewHolder.createViewHolder(context,                    mHeaderViews.get(viewType));        } else if (mFootViews.get(viewType) != null) {            holder = ViewHolder.createViewHolder(context,                    mFootViews.get(viewType));        } else {            holder = ViewHolder.createViewHolder(context, parent,                    getViewHolderLaoutId());        }        return holder;    }    /**     * 获取ViewHolder layoutID     *      * @return     */    protected abstract int getViewHolderLaoutId();    /**     * 绑定ViewHolder     */    @Override    public void onBindViewHolder(ViewHolder holder, int position) {        if (!(isHeaderViewPos(position) || isFooterViewPos(position))) {            bindViewHolderData(holder, position);        }    }    /**     * 子类实现绑定ViewHolder     *      * @param holder     * @param position     */    protected abstract void bindViewHolderData(ViewHolder holder, int position);    /**     * 获取数据     *      * @return     */    public List<T> getListData() {        return list;    }    /**     * 获取总条目     */    @Override    public int getItemCount() {        return getHeadersCount() + getRealItemCount() + getFootersCount();    }    /**     * 判断是否是头部     *      * @param position     * @return     */    private boolean isHeaderViewPos(int position) {        return position < getHeadersCount();    }    /**     * 判断是否是底部     *      * @param position     * @return     */    private boolean isFooterViewPos(int position) {        return position >= getHeadersCount() + getRealItemCount();    }    /**     * 添加头部     *      * @param view     */    public void addHeaderView(View view) {        mHeaderViews.put(mHeaderViews.size() + BASE_ITEM_TYPE_HEADER, view);    }    /**     * 添加底部     *      * @param view     */    public void addFootView(View viewid) {        mFootViews.put(mFootViews.size() + BASE_ITEM_TYPE_FOOTER, viewid);    }    /**     * 获取数据条目     *      * @return     */    public int getRealItemCount() {        return list.size();    }    /**     * 获取头部条目     *      * @return     */    public int getHeadersCount() {        return mHeaderViews.size();    }    /**     * 获取底部条目     *      * @return     */    public int getFootersCount() {        return mFootViews.size();    }    /**     * 移除第 i 个头部（0开始）     *      * @param i     */    public void removeHeaderView(int i) {        if (mHeaderViews.get(BASE_ITEM_TYPE_HEADER + i) != null) {            mHeaderViews.remove(BASE_ITEM_TYPE_HEADER + i);        }    }    /**     * 移除第 i 个底部（0开始）     *      * @param i     */    public void removeFooterView(int i) {        if (mFootViews.get(BASE_ITEM_TYPE_FOOTER + i) != null) {            mFootViews.remove(BASE_ITEM_TYPE_FOOTER + i);        }    }    @Override    public int getItemViewType(int position) {        if (isHeaderViewPos(position)) {            return mHeaderViews.keyAt(position);        } else if (isFooterViewPos(position)) {            return mFootViews.keyAt(position - getHeadersCount()                    - getRealItemCount());        }        return position - getHeadersCount();    }    /**     * GridLayoutManager 时，头部和底部都要占据整行     *     * @param recyclerView     */    @Override    public void onAttachedToRecyclerView(RecyclerView recyclerView) {        super.onAttachedToRecyclerView(recyclerView);        if (recyclerView == null) {            return;        }        final RecyclerView.LayoutManager layoutManager = recyclerView                .getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            ((GridLayoutManager) layoutManager)                    .setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {                        @Override                        public int getSpanSize(int position) {                            return (isHeaderViewPos(position) || isFooterViewPos(position)) ? ((GridLayoutManager) layoutManager)                                    .getSpanCount() : 1;                        }                    });        }    }    /**     * StaggeredGridLayoutManager 时，头部和底部都要占据整行     *      * @param holder     */    @Override    public void onViewAttachedToWindow(ViewHolder holder) {        super.onViewAttachedToWindow(holder);        int position = holder.getLayoutPosition();        if (isHeaderViewPos(position) || isFooterViewPos(position)) {            ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();            if (lp != null                    && lp instanceof StaggeredGridLayoutManager.LayoutParams) {                StaggeredGridLayoutManager.LayoutParams p = (StaggeredGridLayoutManager.LayoutParams) lp;                p.setFullSpan(true);            }        }    }}

5、文中用到的ViewHolder的封装

import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Paint;import android.graphics.Typeface;import android.graphics.drawable.Drawable;import android.os.Build;import android.support.v7.widget.RecyclerView;import android.text.util.Linkify;import android.util.SparseArray;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.view.animation.AlphaAnimation;import android.widget.Checkable;import android.widget.ImageView;import android.widget.ProgressBar;import android.widget.RatingBar;import android.widget.TextView;public class ViewHolder extends RecyclerView.ViewHolder {    private SparseArray<View> mViews;    private View mConvertView;    private Context mContext;    public ViewHolder(Context context, View itemView) {        super(itemView);        mContext = context;        mConvertView = itemView;        mViews = new SparseArray<View>();    }    public static ViewHolder createViewHolder(Context context, View itemView) {        ViewHolder holder = new ViewHolder(context, itemView);        return holder;    }    public static ViewHolder createViewHolder(Context context,            ViewGroup parent, int layoutId) {        View itemView = LayoutInflater.from(context).inflate(layoutId, parent,                false);        ViewHolder holder = new ViewHolder(context, itemView);        return holder;    }    /**     * 通过viewId获取控件     *     * @param viewId     * @return     */    public <T extends View> T getView(int viewId) {        View view = mViews.get(viewId);        if (view == null) {            view = mConvertView.findViewById(viewId);            mViews.put(viewId, view);        }        return (T) view;    }    public View getConvertView() {        return mConvertView;    }    /**** 以下为辅助方法 *****/    /**     * 获取控件     */    public ImageView getImageView(int viewId) {        ImageView iv = getView(viewId);        return iv;    }    public TextView getTextView(int viewId) {        TextView tv = getView(viewId);        return tv;    }    /**     * 设置TextView的值     *     * @param viewId     * @param text     * @return     */    public ViewHolder setText(int viewId, String text) {        TextView tv = getView(viewId);        tv.setText(text);        return this;    }    public ViewHolder setImageResource(int viewId, int resId) {        ImageView view = getView(viewId);        view.setImageResource(resId);        return this;    }    public ViewHolder setImageBitmap(int viewId, Bitmap bitmap) {        ImageView view = getView(viewId);        view.setImageBitmap(bitmap);        return this;    }    public ViewHolder setImageDrawable(int viewId, Drawable drawable) {        ImageView view = getView(viewId);        view.setImageDrawable(drawable);        return this;    }    public ViewHolder setBackgroundColor(int viewId, int color) {        View view = getView(viewId);        view.setBackgroundColor(color);        return this;    }    public ViewHolder setBackgroundRes(int viewId, int backgroundRes) {        View view = getView(viewId);        view.setBackgroundResource(backgroundRes);        return this;    }    public ViewHolder setTextColor(int viewId, int textColor) {        TextView view = getView(viewId);        view.setTextColor(textColor);        return this;    }    public ViewHolder setTextColorRes(int viewId, int textColorRes) {        TextView view = getView(viewId);        view.setTextColor(mContext.getResources().getColor(textColorRes));        return this;    }    @SuppressLint("NewApi")    public ViewHolder setAlpha(int viewId, float value) {        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {            getView(viewId).setAlpha(value);        } else {            // Pre-honeycomb hack to set Alpha value            AlphaAnimation alpha = new AlphaAnimation(value, value);            alpha.setDuration(0);            alpha.setFillAfter(true);            getView(viewId).startAnimation(alpha);        }        return this;    }    public ViewHolder setVisible(int viewId, boolean visible) {        View view = getView(viewId);        view.setVisibility(visible ? View.VISIBLE : View.GONE);        return this;    }    public ViewHolder linkify(int viewId) {        TextView view = getView(viewId);        Linkify.addLinks(view, Linkify.ALL);        return this;    }    public ViewHolder setTypeface(Typeface typeface, int... viewIds) {        for (int viewId : viewIds) {            TextView view = getView(viewId);            view.setTypeface(typeface);            view.setPaintFlags(view.getPaintFlags() | Paint.SUBPIXEL_TEXT_FLAG);        }        return this;    }    public ViewHolder setProgress(int viewId, int progress) {        ProgressBar view = getView(viewId);        view.setProgress(progress);        return this;    }    public ViewHolder setProgress(int viewId, int progress, int max) {        ProgressBar view = getView(viewId);        view.setMax(max);        view.setProgress(progress);        return this;    }    public ViewHolder setMax(int viewId, int max) {        ProgressBar view = getView(viewId);        view.setMax(max);        return this;    }    public ViewHolder setRating(int viewId, float rating) {        RatingBar view = getView(viewId);        view.setRating(rating);        return this;    }    public ViewHolder setRating(int viewId, float rating, int max) {        RatingBar view = getView(viewId);        view.setMax(max);        view.setRating(rating);        return this;    }    public ViewHolder setTag(int viewId, Object tag) {        View view = getView(viewId);        view.setTag(tag);        return this;    }    public ViewHolder setTag(int viewId, int key, Object tag) {        View view = getView(viewId);        view.setTag(key, tag);        return this;    }    public ViewHolder setChecked(int viewId, boolean checked) {        Checkable view = (Checkable) getView(viewId);        view.setChecked(checked);        return this;    }    /**     * 关于事件的     */    public ViewHolder setOnClickListener(int viewId,            View.OnClickListener listener) {        View view = getView(viewId);        view.setOnClickListener(listener);        return this;    }    public ViewHolder setOnTouchListener(int viewId,            View.OnTouchListener listener) {        View view = getView(viewId);        view.setOnTouchListener(listener);        return this;    }    public ViewHolder setOnLongClickListener(int viewId,            View.OnLongClickListener listener) {        View view = getView(viewId);        view.setOnLongClickListener(listener);        return this;    }}