Android RecyclerView滑动到底部/上拉/上拉见底自动加载更多实现以及点击/长按事件处理

青旅半醒 2023-10-17 18:48 6阅读 0赞

**Android RecyclerView滑动到底部/上拉/上拉见底自动加载更多实现以及点击/长按事件处理**

Android RecyclerView下拉加载更多有Android谷歌官方的实现，实现的方式是通过SwipeRefreshLayout把RecyclerView包裹起来，然后就可以通过SwipeRefreshLayout的回调接口实现下拉刷新功能。  
Android上拉加载上拉刷新的实现没有官方统一策略，现在我给出一个实现好的工具类：

import android.support.v7.widget.RecyclerView;
    
    /**
     * Created by fly on 2018/3/22.
     */
    
    public class RecyclerViewUtil {
        private boolean enable = true;
        private RecyclerView mRecyclerView;
        private RecyclerViewLoadMoreListener mRecyclerViewLoadMoreListener;
    
        public RecyclerViewUtil(RecyclerView mRecyclerView) {
            this.mRecyclerView = mRecyclerView;
        }
    
        public void setRecyclerViewLoadMoreListener(RecyclerViewLoadMoreListener listener) {
            this.mRecyclerViewLoadMoreListener = listener;
            mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                @Override
                public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                    super.onScrollStateChanged(recyclerView, newState);
    
                    if (newState == RecyclerView.SCROLL_STATE_IDLE && isBottom(mRecyclerView)) {
                        if (enable && mRecyclerViewLoadMoreListener != null) {
                            mRecyclerViewLoadMoreListener.onLoadMore();
                        }
                    }
                }
            });
        }
    
        public void setLoadMoreEnable(boolean enable) {
            this.enable = enable;
        }
    
        private boolean isBottom(RecyclerView recyclerView) {
            if (recyclerView == null)
                return false;
    
            if (recyclerView.computeVerticalScrollExtent() + recyclerView.computeVerticalScrollOffset() >= recyclerView.computeVerticalScrollRange())
                return true;
    
            return false;
        }
    
        public interface RecyclerViewLoadMoreListener {
            public void onLoadMore();
        }
    }

使用方式，构造一个RecyclerViewUtil,把RecyclerView传递进去，就可以使用了。如：

import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import java.util.ArrayList;
    import java.util.Random;
    
    public class MainActivity extends AppCompatActivity {
    
        private RecyclerViewAdapter mAdapter;
        private ArrayList<String> data;
    
        private int START_POS = 0;
        private RecyclerViewUtil mRecyclerViewUtil;
    
        private Random random = new Random();
    
        private int MAX_COUNT = 20;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            data = new ArrayList<>();
            int count = random.nextInt(MAX_COUNT);
            for (int i = 0; i < count; i++) {
                data.add(String.valueOf(i));
            }
    
            START_POS = START_POS + count;
    
            setContentView(R.layout.activity_main);
    
            RecyclerView mRecyclerView = findViewById(R.id.recycler_view);
            LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(this);
            mLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            mRecyclerView.setLayoutManager(mLinearLayoutManager);
    
            mAdapter = new RecyclerViewAdapter();
            mRecyclerView.setAdapter(mAdapter);
    
            mRecyclerViewUtil = new RecyclerViewUtil(mRecyclerView);
            mRecyclerViewUtil.setRecyclerViewLoadMoreListener(new RecyclerViewUtil.RecyclerViewLoadMoreListener() {
                @Override
                public void onLoadMore() {
                    Toast.makeText(getApplicationContext(), "已经到底，加载更多...", Toast.LENGTH_SHORT).show();
                    mRecyclerViewUtil.setLoadMoreEnable(false);
    
                    load(START_POS, random.nextInt(MAX_COUNT));
                }
            });
        }
    
        private void load(int startPos, int count) {
            for (int i = 0; i < count; i++) {
                data.add(startPos + i + "");
            }
    
            mAdapter.notifyDataSetChanged();
            Toast.makeText(getApplicationContext(), "加载了" + count + " 条数据", Toast.LENGTH_SHORT).show();
    
            START_POS = startPos + count;
            mRecyclerViewUtil.setLoadMoreEnable(true);
        }
    
        public class RecyclerViewAdapter extends RecyclerView.Adapter<MyViewHolder> {
    
            @Override
            public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
                View view = LayoutInflater.from(getApplicationContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
                MyViewHolder holder = new MyViewHolder(view);
                return holder;
            }
    
            @Override
            public void onBindViewHolder(MyViewHolder holder, int position) {
                holder.text.setText(data.get(position));
            }
    
            @Override
            public int getItemCount() {
                return data.size();
            }
        }
    
        private class MyViewHolder extends RecyclerView.ViewHolder {
            public TextView text;
    
            public MyViewHolder(View itemView) {
                super(itemView);
                text = itemView.findViewById(android.R.id.text1);
            }
        }
    }

另外，Android RecyclerView也没有实现item点击或长按事件的触发，以前我写过一篇文章，实现了该功能，《Android RecyclerView单击、长按事件:基于OnItemTouchListener +GestureDetector标准实现（二），封装抽取成通用工具类》链接：https://blog.csdn.net/zhangphil/article/details/53231344

可以把这两套方案整合在一起，实现一个完整的Android RecyclerView工具包类。整合在一起的新RecyclerViewUtil：

import android.content.Context;
    import android.support.v7.widget.RecyclerView;
    import android.view.GestureDetector;
    import android.view.MotionEvent;
    import android.view.View;
    
    /**
     * Created by fly on 2018/3/22.
     */
    
    public class RecyclerViewUtil {
        private boolean enable = true;
        private RecyclerView mRecyclerView;
        private OnLoadMoreListener mOnLoadMoreListener;
    
        private GestureDetector mGestureDetector = null;
        private RecyclerView.SimpleOnItemTouchListener mSimpleOnItemTouchListener;
        private OnItemClickListener mOnItemClickListener = null;
        private OnItemLongClickListener mOnItemLongClickListener = null;
    
        public RecyclerViewUtil(Context mContext, RecyclerView recyclerView) {
            this.mRecyclerView = recyclerView;
    
            mGestureDetector = new GestureDetector(mContext, new GestureDetector.SimpleOnGestureListener() {
                //长按事件
                @Override
                public void onLongPress(MotionEvent e) {
                    super.onLongPress(e);
                    if (mOnItemLongClickListener != null) {
                        View childView = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
                        if (childView != null) {
                            int position = mRecyclerView.getChildLayoutPosition(childView);
                            mOnItemLongClickListener.onItemLongClick(position, childView);
                        }
                    }
                }
    
                //单击事件
                @Override
                public boolean onSingleTapUp(MotionEvent e) {
                    if (mOnItemClickListener != null) {
                        View childView = mRecyclerView.findChildViewUnder(e.getX(), e.getY());
                        if (childView != null) {
                            int position = mRecyclerView.getChildLayoutPosition(childView);
                            mOnItemClickListener.onItemClick(position, childView);
                            return true;
                        }
                    }
    
                    return super.onSingleTapUp(e);
                }
            });
    
            mSimpleOnItemTouchListener = new RecyclerView.SimpleOnItemTouchListener() {
                @Override
                public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
                    if (mGestureDetector.onTouchEvent(e)) {
                        return true;
                    }
                    return false;
                }
            };
    
            mRecyclerView.addOnItemTouchListener(mSimpleOnItemTouchListener);
        }
    
        public void setOnLoadMoreListener(OnLoadMoreListener listener) {
            this.mOnLoadMoreListener = listener;
            mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                @Override
                public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                    super.onScrollStateChanged(recyclerView, newState);
    
                    if (newState == RecyclerView.SCROLL_STATE_IDLE && isBottom(mRecyclerView)) {
                        if (enable && mOnLoadMoreListener != null) {
                            mOnLoadMoreListener.onLoadMore();
                        }
                    }
                }
            });
        }
    
        /**
         * true 打开上拉加载 false，关闭上拉加载
         * @param enable
         */
        public void setLoadMoreEnable(boolean enable) {
            this.enable = enable;
        }
    
        private boolean isBottom(RecyclerView recyclerView) {
            if (recyclerView == null)
                return false;
    
            if (recyclerView.computeVerticalScrollExtent() + recyclerView.computeVerticalScrollOffset() >= recyclerView.computeVerticalScrollRange())
                return true;
    
            return false;
        }
    
        public interface OnLoadMoreListener {
            public void onLoadMore();
        }
    
        public void setOnItemClickListener(OnItemClickListener listener) {
            mOnItemClickListener = listener;
        }
    
        public void setOnItemLongClickListener(OnItemLongClickListener listener) {
            mOnItemLongClickListener = listener;
        }
    
        //长按事件接口
        public interface OnItemLongClickListener {
            public void onItemLongClick(int position, View view);
        }
    
        //单击事件接口
        public interface OnItemClickListener {
            public void onItemClick(int position, View view);
        }
    }

新的RecyclerViewUtil实现了上拉加载更多，单击，长按事件的处理。

使用方式和上一个例子类似：

import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import java.util.ArrayList;
    import java.util.Random;
    
    public class MainActivity extends AppCompatActivity {
    
        private RecyclerViewAdapter mAdapter;
        private ArrayList<String> data;
    
        private int START_POS = 0;
        private RecyclerViewUtil mRecyclerViewUtil;
    
        private Random random = new Random();
    
        private int MAX_COUNT = 20;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            data = new ArrayList<>();
            int count = random.nextInt(MAX_COUNT);
            for (int i = 0; i < count; i++) {
                data.add(String.valueOf(i));
            }
    
            START_POS = START_POS + count;
    
            setContentView(R.layout.activity_main);
    
            RecyclerView mRecyclerView = findViewById(R.id.recycler_view);
            LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(this);
            mLinearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            mRecyclerView.setLayoutManager(mLinearLayoutManager);
    
            mAdapter = new RecyclerViewAdapter();
            mRecyclerView.setAdapter(mAdapter);
    
            mRecyclerViewUtil = new RecyclerViewUtil(this, mRecyclerView);
            mRecyclerViewUtil.setOnLoadMoreListener(new RecyclerViewUtil.OnLoadMoreListener() {
                @Override
                public void onLoadMore() {
                    Toast.makeText(getApplicationContext(), "已经到底，加载更多...", Toast.LENGTH_SHORT).show();
                    mRecyclerViewUtil.setLoadMoreEnable(false);
                    load(START_POS, random.nextInt(MAX_COUNT));
                }
            });
    
            mRecyclerViewUtil.setOnItemClickListener(new RecyclerViewUtil.OnItemClickListener() {
                @Override
                public void onItemClick(int position, View view) {
                    Toast.makeText(getApplicationContext(), "单击" + position, Toast.LENGTH_SHORT).show();
                }
            });
    
            mRecyclerViewUtil.setOnItemLongClickListener(new RecyclerViewUtil.OnItemLongClickListener() {
                @Override
                public void onItemLongClick(int position, View view) {
                    Toast.makeText(getApplicationContext(), "长按" + position, Toast.LENGTH_SHORT).show();
                }
            });
        }
    
        private void load(int startPos, int count) {
            for (int i = 0; i < count; i++) {
                data.add(startPos + i + "");
            }
    
            mAdapter.notifyDataSetChanged();
            Toast.makeText(getApplicationContext(), "加载了" + count + " 条数据", Toast.LENGTH_SHORT).show();
    
            START_POS = startPos + count;
            mRecyclerViewUtil.setLoadMoreEnable(true);
        }
    
        public class RecyclerViewAdapter extends RecyclerView.Adapter<MyViewHolder> {
    
            @Override
            public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
                View view = LayoutInflater.from(getApplicationContext()).inflate(android.R.layout.simple_list_item_1, parent, false);
                MyViewHolder holder = new MyViewHolder(view);
                return holder;
            }
    
            @Override
            public void onBindViewHolder(MyViewHolder holder, int position) {
                holder.text.setText(data.get(position));
            }
    
            @Override
            public int getItemCount() {
                return data.size();
            }
        }
    
        private class MyViewHolder extends RecyclerView.ViewHolder {
            public TextView text;
    
            public MyViewHolder(View itemView) {
                super(itemView);
                text = itemView.findViewById(android.R.id.text1);
            }
        }
    }