Android RecyclerView添加头尾布局

RecyclerView添加头尾布局方式有多种，一般常用的方式是利用ItemViewType，将头尾布局当做指定类型的item成为RecyclerView的子元素，这里面由于只涉及到RecyclerView基础方法，故直接上代码
先制作一个基类

import android.content.Context;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

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

public abstract class BaseRecyclerAdapter<T> extends RecyclerView.Adapter<BaseRecyclerAdapter.BaseRecyclerViewHolder> {
    /**
     * normal item view type
     */
    public static final int TYPE_NORMAL = 0;
    /**
     * header view type
     */
    public static final int TYPE_HEADER = 1;
    /**
     * footer view type
     */
    public static final int TYPE_FOOTER = 2;
    private View mHeaderView;
    private View mFooterView;
    private OnItemClickListener onItemClickListener;

    public List<T> mData = new ArrayList<>();

    public void setData(List<T> data) {
        if (data == null) {
            mData.clear();
            return;
        }
        mData.clear();
        mData.addAll(data);
    }

    public T getItemData(int dataPosition) {
        T res = null;
        if (dataPosition < mData.size()) {
            res = mData.get(dataPosition);
        }
        return res;
    }

    public void clearData() {
        if (mData != null) {
            mData.clear();
        }
    }

    public int getDataSize() {
        return mData.size();
    }

    public void setOnItemClickListener(OnItemClickListener li) {
        onItemClickListener = li;
    }

    /**
     * Add header view
     *
     * @param headerView
     */
    public void setHeaderView(View headerView) {
        mHeaderView = headerView;
        notifyItemInserted(0);
    }

    /**
     * Add header view res
     *
     * @param c,layoutId
     */
    public void setHeaderView(Context c, int layoutId) {
        if (c == null && layoutId < 0) {
            return;
        }
        mHeaderView = LayoutInflater.from(c).inflate(layoutId, (ViewGroup) null);
        notifyItemInserted(0);
    }

    /**
     * Get header view
     *
     * @return
     */
    public View getHeaderView() {
        return mHeaderView;
    }

    /**
     * Add footer view
     *
     * @param footerView
     */
    public void setFooterView(View footerView) {
        this.mFooterView = footerView;
        notifyItemInserted(getItemCount() - 1);
    }

    /**
     * Add footer view res
     *
     * @param c,layoutId
     */
    public void setFooterView(Context c, int layoutId) {
        if (c == null && layoutId < 0) {
            return;
        }
        this.mFooterView = LayoutInflater.from(c).inflate(layoutId, (ViewGroup) null);
        notifyItemInserted(getItemCount() - 1);
    }

    /**
     * Get footer view
     *
     * @return
     */
    public View getFooterView() {
        return this.mFooterView;
    }

    @Override
    public int getItemViewType(int position) {
        if (mHeaderView != null && position == 0) {
            return TYPE_HEADER;
        }
        if (mFooterView != null && position == getItemCount() - 1) {
            return TYPE_FOOTER;
        }
        return TYPE_NORMAL;
    }

    /**
     * get item data real position
     *
     * @param holder
     * @return
     */
    private int getRealPosition(BaseRecyclerViewHolder holder) {
        int position = holder.getPosition();
        return mHeaderView == null ? position : position - 1;
    }

    @Override
    public BaseRecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (mHeaderView != null && viewType == TYPE_HEADER) {
            return new HeaderViewHolder(mHeaderView);
        }
        if (mFooterView != null && viewType == TYPE_FOOTER) {
            return new FooterViewHolder(mFooterView);
        }
        return onCreateRecyclerViewHolder(parent, viewType);
    }


    public void onBindViewHolder(BaseRecyclerViewHolder holder, int position) {
        //如果是header footer view就直接返回,不需要绑定数据
        if (getItemViewType(position) == TYPE_HEADER) {
            return;
        }
        if (getItemViewType(position) == TYPE_FOOTER) {
            return;
        }
        final int pos = getRealPosition(holder);
        final T data = mData.get(pos);
        bindData(holder, position);

        if (onItemClickListener != null) {
            holder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    onItemClickListener.onItemClick(pos, data);
                }
            });
        }
    }

    @Override
    public int getItemCount() {
        int count = mData.size();
        if (mHeaderView != null) {
            count++;
        }
        if (mFooterView != null) {
            count++;
        }
        return count;
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();
        if (manager instanceof GridLayoutManager) {
            final GridLayoutManager gridLayoutManager = ((GridLayoutManager) manager);
            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
                @Override
                public int getSpanSize(int position) {
                    if (getItemViewType(position) == TYPE_HEADER) {
                        return gridLayoutManager.getSpanCount();
                    }
                    if (getItemViewType(position) == TYPE_FOOTER) {
                        return gridLayoutManager.getSpanCount();
                    }
                    return 1;
                }
            });
        }
        //LinearLayoutManager不需要设置
    }

    /**
     * Create item view holder
     *
     * @param parent
     * @param viewType
     * @return
     */
    protected abstract BaseRecyclerViewHolder onCreateRecyclerViewHolder(ViewGroup parent, int viewType);

    /**
     * Bind data.
     *
     * @param holder
     * @param position
     */
    public abstract void bindData(BaseRecyclerViewHolder holder, int position);

    static abstract class BaseRecyclerViewHolder extends RecyclerView.ViewHolder {

        public BaseRecyclerViewHolder(View itemView) {
            super(itemView);
            findView(itemView);
        }

        public abstract void findView(View v);
    }

    /**
     * header view ViewHolder
     */
    class HeaderViewHolder extends BaseRecyclerViewHolder {

        public HeaderViewHolder(View itemView) {
            super(itemView);
        }

        @Override
        public void findView(View v) {
        }
    }

    /**
     * footer view ViewHolder
     */
    class FooterViewHolder extends BaseRecyclerViewHolder {

        public FooterViewHolder(View itemView) {
            super(itemView);
        }

        @Override
        public void findView(View v) {
        }
    }

    /**
     * item 点击事件接口
     *
     * @param <T>position 数据实际位置
     */
    public interface OnItemClickListener<T> {
        void onItemClick(int position, T data);
    }
}

使用时：
1.直接继承BaseRecyclerAdapter

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;
import com.mvp.demo.R;
import java.util.Random;

public class CustomAdapter extends BaseRecyclerAdapter<Integer> {

    Context mContext;

    public CustomAdapter(Context c) {
        this.mContext = c;
    }

    @Override
    protected BaseRecyclerViewHolder onCreateRecyclerViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.item_layout, null);
        return new CustomHolder(view);
    }

    @Override
    public void bindData(BaseRecyclerViewHolder holder, int position) {
        CustomHolder customHolder = (CustomHolder) holder;
        customHolder.content.setText(mData.get(position - 1) + "");
    }

    class CustomHolder extends BaseRecyclerViewHolder {

        public RelativeLayout container;
        public TextView content;
        public CustomHolder(View itemView) {
            super(itemView);
        }

        @Override
        public void findView(View v) {
            container = itemView.findViewById(R.id.container);
            content = itemView.findViewById(R.id.content);
            ViewGroup.LayoutParams layoutParams = container.getLayoutParams();
            layoutParams.height = mContext.getResources().getDisplayMetrics().widthPixels / 3;
            container.setLayoutParams(layoutParams);
            Random random = new Random();
            int ranColor = 0xff000000 | random.nextInt(0x00ffffff);
            content.setBackgroundColor(ranColor);
        }
    }
}

2.在activity中初始化：

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
        initData();
    }

    private void initData() {
        mData.clear();
        for (int i = 0; i < 8; i++) {
            mData.add(i);
        }
        mCustomAdapter.setData(mData);
        mRecyclerView.setAdapter(mCustomAdapter);
    }

    private void init() {
        mRecyclerView = findViewById(R.id.recycler);
        mRecyclerView.setLayoutManager(new GridLayoutManager(this, 3));
        mCustomAdapter = new CustomAdapter(this);
        mCustomAdapter.setFooterView(this, R.layout.header_footer_layout);
        mCustomAdapter.setHeaderView(this, R.layout.header_footer_layout);
        mCustomAdapter.setOnItemClickListener(new BaseRecyclerAdapter.OnItemClickListener<Integer>() {
            @Override
            public void onItemClick(int position, Integer data) {
                Toast.makeText(getApplicationContext(), data + "", Toast.LENGTH_SHORT).show();
            }
        });
    }

布局文件：
header_footer_layout.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:background="@android:color/darker_gray">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:text="Header or Footer" />

    </RelativeLayout>
</android.support.constraint.ConstraintLayout>

item_layout.xml:

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/content"
            android:layout_centerInParent="true"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:textSize="20sp"
            android:textColor="@android:color/white"
            android:gravity="center"
            />
    </RelativeLayout>
</android.support.constraint.ConstraintLayout>

效果图：

recycler示例.png

当然我们也可以将头尾布局放到List数据里，设置不同的type，达到同样的效果