Android开发 封装RecyclerView实现向上拉动加载功能 UpLoadingRecyclerView

前言

　　在很早以前在本人的博客 https://www.cnblogs.com/guanxinjing/p/10299889.html  提供了用RecyclerView实现上拉加载数据的思维，但是用这个方式实现后，每一个上拉加载页面几乎都需要重写大量重复代码。所以进行了重新的封装，以方便使用并且减少重复代码量。如果刚点击这个博客建议看看之前的博客，之前的博客实现思路比较，清晰讲解部分也比较多。

封装后的RecyclerView

使用时请注意，这里以内部类的形式封装了适配器，请使用这里封装的适配器配合一起使用。

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.ColorInt;
import androidx.annotation.IntDef;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.StringRes;
import androidx.recyclerview.widget.RecyclerView;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.SOURCE;

public class UpLoadingRecyclerView extends RecyclerView {
    private boolean isScroll;
    private float downY;
    private int mHeightPixels;
    private OnUpScrollListener mOnUpScrollListener;
    private OnUpPullLoadListener mOnUpPullLoadListener;

    public UpLoadingRecyclerView(@NonNull Context context) {
        super(context);
        DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
        mHeightPixels = displayMetrics.heightPixels;
    }

    public UpLoadingRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
        mHeightPixels = displayMetrics.heightPixels;
    }

    public UpLoadingRecyclerView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
        mHeightPixels = displayMetrics.heightPixels;
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        return super.dispatchTouchEvent(ev);
    }

    /**
     * 重写拦截的目的是只拦截移动事件,不拦截其他触摸事件
     *
     * @param e
     * @return
     */
    @Override
    public boolean onInterceptTouchEvent(MotionEvent e) {
        super.onInterceptTouchEvent(e);//一定要super.onInterceptTouchEvent(e);不要让RecyclerView的其他事件分发受到影响，否则会出现不滚动的问题
        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:
                isScroll = false;//按下不拦截
                downY = e.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                if (Math.abs(downY - e.getY()) >= ViewConfiguration.get(
                        getContext()).getScaledTouchSlop()) {//判断是否产生了最小滑动
                    isScroll = true;//移动了拦截触摸事件
                } else {
                    isScroll = false;
                }
                break;
            case MotionEvent.ACTION_UP:
                isScroll = false;//松开不拦截
                break;
        }

        return isScroll;
    }


    @Override
    public boolean onFilterTouchEventForSecurity(MotionEvent event) {
        return super.onFilterTouchEventForSecurity(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent e) {
        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN:
                break;
            case MotionEvent.ACTION_MOVE:
                break;
            case MotionEvent.ACTION_UP:
                if (downY - e.getY() > mHeightPixels / 5) {//判断是不是从下往上滑动了屏幕的5分之一
                    if (mOnUpScrollListener != null) {
                        mOnUpScrollListener.onScroll();
                    }
                    if (getAdapter() != null && mOnUpPullLoadListener != null && getAdapter() instanceof Adapter) {
                        Adapter adapter = (Adapter) getAdapter();
                        if (adapter.isFooterPullUpLoading() && adapter.isFooterItemPosition()) {
                            mOnUpPullLoadListener.OnUpPullLoad();
                        }
                    }

                }
                break;

        }
        return super.onTouchEvent(e);
    }

    public void setOnUpScrollListener(OnUpScrollListener listener) {
        this.mOnUpScrollListener = listener;

    }

    public void setOnUpPullLoadListener(OnUpPullLoadListener onUpPullLoadListener) {
        this.mOnUpPullLoadListener = onUpPullLoadListener;
    }

    public interface OnUpScrollListener {
        void onScroll();

    }

    public interface OnUpPullLoadListener {
        void OnUpPullLoad();
    }

    public static abstract class Adapter<VH extends ViewHolder> extends RecyclerView.Adapter {
        private static final int FOOTER_VIEW = -101;
        private int currentFooterStatus = FooterStatus.FOOTER_NO_MORE_DATA;  //当前页角item状态
        private int scrollPosition;                                          //滚动位置


        public abstract ViewHolder onCreateItemViewHolder(@NonNull ViewGroup parent, int viewType);

        public abstract ViewHolder onCreateFooterViewHolder(@NonNull ViewGroup parent, int viewType);

        public abstract void onBindItemViewHolder(@NonNull ViewHolder holder, int position);

        public abstract void onBindFooterViewHolder(@NonNull ViewHolder holder, @FooterStatus int currentFooterStatus);

        public abstract int getItemViewCount();

        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            if (viewType != FOOTER_VIEW) {
                return onCreateItemViewHolder(parent, viewType);
            }
            return onCreateFooterViewHolder(parent, viewType);
        }


        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            scrollPosition = position;
            if (getItemViewType(position) != FOOTER_VIEW) {
                onBindItemViewHolder(holder, position);
                return;
            }
            onBindFooterViewHolder(holder, currentFooterStatus);
        }
        
        /**
         * 判断是否到了页尾的位置上
         *
         * @return
         */
        public boolean isFooterItemPosition() {
            return scrollPosition >= getItemCount() - 5;
        }

        @Override
        public int getItemViewType(int position) {
            if (getItemCount() != 0 && position == getItemCount() - 1) {
                return FOOTER_VIEW;
            }
            return super.getItemViewType(position);
        }

        @Override
        public int getItemCount() {
            return getItemViewCount() == 0 ? 0 : getItemViewCount() + 1;
        }

        /**
         * 修改页脚状态为加载中
         */
        public void setFooterLoading() {
            currentFooterStatus = FooterStatus.FOOTER_LOADING;
            notifyDataSetChanged();
        }

        /**
         * 修改页脚状态为网络异常
         */
        public void setFooterNetWorkError() {
            currentFooterStatus = FooterStatus.FOOTER_ERROR;
            notifyDataSetChanged();
        }

        /**
         * 修改页脚状态为没有更多数据
         */
        public void setFooterNoMoreData() {
            currentFooterStatus = FooterStatus.FOOTER_NO_MORE_DATA;
            notifyDataSetChanged();
        }

        /**
         * 修改页脚状态为上拉加载数据
         */
        public void setFooterPullUpLoading() {
            currentFooterStatus = FooterStatus.FOOTER_PULL_UP_LOADING;
            notifyDataSetChanged();
        }

        public boolean isFooterLoading() {
            return currentFooterStatus == FooterStatus.FOOTER_LOADING;
        }

        public boolean isFooterNetWorkError() {
            return currentFooterStatus == FooterStatus.FOOTER_ERROR;
        }

        public boolean isFooterNoMoreData() {
            return currentFooterStatus == FooterStatus.FOOTER_NO_MORE_DATA;
        }

        public boolean isFooterPullUpLoading() {
            return currentFooterStatus == FooterStatus.FOOTER_PULL_UP_LOADING;
        }

        /**
         * 创建使用简单页尾
         *
         * @param parent
         * @param viewType
         * @param textSize
         * @param textColor
         * @return
         */
        public SimpleFooterViewHolder createSimpleFooterView(@NonNull ViewGroup parent, int viewType, float textSize, @ColorInt int textColor) {
            if (viewType == Adapter.FOOTER_VIEW) {
                TextView textView = new TextView(parent.getContext());
                if(textSize != 0){
                    textView.setTextSize(textSize);
                }
                if (textColor != 0){
                    textView.setTextColor(textColor);
                }
                textView.setGravity(Gravity.CENTER);
                textView.post(new Runnable() {
                    @Override
                    public void run() {
                        ViewGroup.LayoutParams layoutParams = textView.getLayoutParams();
                        layoutParams.width = ViewGroup.LayoutParams.MATCH_PARENT;
                        textView.setLayoutParams(layoutParams);

                    }
                });
                return new SimpleFooterViewHolder(textView);

            }
            return null;
        }

        /**
         * 绑定简单页尾的ViewHolder
         *
         * @param holder
         * @param pullUpLoadingText  提示 上拉加载数据
         * @param loadingText        提示 数据加载中
         * @param errorText          提示 网络异常
         * @param notMoreDataText    提示 没有更多数据了
         */
        public void bindSimpleFooterViewHolder(@NonNull ViewHolder holder, @StringRes int pullUpLoadingText, @StringRes int loadingText, @StringRes int errorText, @StringRes int notMoreDataText) {
            if (holder instanceof SimpleFooterViewHolder) {
                switch (currentFooterStatus) {
                    case FooterStatus.FOOTER_PULL_UP_LOADING:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(pullUpLoadingText);
                        break;
                    case FooterStatus.FOOTER_LOADING:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(loadingText);
                        break;
                    case FooterStatus.FOOTER_ERROR:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(errorText);
                        break;
                    case FooterStatus.FOOTER_NO_MORE_DATA:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(notMoreDataText);
                        break;
                    default:
                        break;
                }
            }
        }

        /**
         * 绑定简单页尾的ViewHolder
         *
         * @param holder
         * @param pullUpLoadingText 提示 上拉加载数据
         * @param loadingText       提示 数据加载中
         * @param errorText         提示 网络异常
         * @param notMoreDataText   提示 没有更多数据了
         */
        public void bindSimpleFooterViewHolder(@NonNull ViewHolder holder, String pullUpLoadingText, String loadingText, String errorText, String notMoreDataText) {
            if (holder instanceof SimpleFooterViewHolder) {
                switch (currentFooterStatus) {
                    case FooterStatus.FOOTER_PULL_UP_LOADING:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(pullUpLoadingText);
                        break;
                    case FooterStatus.FOOTER_LOADING:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(loadingText);
                        break;
                    case FooterStatus.FOOTER_ERROR:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(errorText);
                        break;
                    case FooterStatus.FOOTER_NO_MORE_DATA:
                        ((SimpleFooterViewHolder) holder).footerTextView.setText(notMoreDataText);
                        break;
                    default:
                        break;
                }
            }
        }

        public static class SimpleFooterViewHolder extends ViewHolder {
            TextView footerTextView;

            public SimpleFooterViewHolder(@NonNull View itemView) {
                super(itemView);
                footerTextView = (TextView) itemView;
            }
        }

    }

    @Retention(SOURCE)
    @Target({PARAMETER})
    @IntDef(value = {FooterStatus.FOOTER_PULL_UP_LOADING, FooterStatus.FOOTER_LOADING, FooterStatus.FOOTER_ERROR, FooterStatus.FOOTER_NO_MORE_DATA})
    public @interface FooterStatus {
        int FOOTER_PULL_UP_LOADING = 0;             //提示上拉加载更多
        int FOOTER_LOADING = 1;                     //加载中
        int FOOTER_ERROR = 2;                       //网络异常
        int FOOTER_NO_MORE_DATA = 3;                //没有更多内容
    }
}

使用例子

Adpater

class HomeVideoAdapter extends UpLoadingRecyclerView.Adapter<RecyclerView.ViewHolder> {
    private List<HomeVideoBean> mList = new ArrayList<>();
    private int mSelected = 0;
    private SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss", Locale.getDefault());
    private SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault());
    private OnClickListener mListener;

    public void refreshData(List<HomeVideoBean> list) {
        mList.clear();
        if (list != null) {
            mList.addAll(list);
        }
        notifyDataSetChanged();
    }

    public void addData(List<HomeVideoBean> list) {
        if (list != null) {
            mList.addAll(list);
        }
        notifyDataSetChanged();
    }


    @Override
    public RecyclerView.ViewHolder onCreateItemViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.ad_item_home_video, parent, false);
        HomeVideoViewHolder viewHolder = new HomeVideoViewHolder(view);
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = viewHolder.getAdapterPosition();
                if (position == RecyclerView.NO_POSITION) {
                    return;
                }
                mSelected = position;
                notifyDataSetChanged();
                if (mListener != null) {
                    mListener.onClickItem(mList.get(position));
                }
            }
        });
        return viewHolder;
    }

    @Override
    public RecyclerView.ViewHolder onCreateFooterViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.ad_ad_layout_pull_up_refresh, parent, false);
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mListener != null) {
                    mListener.onClickFooter();
                }
            }
        });
        return new FooterViewHolder(view);
    }

    @Override
    public void onBindItemViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        HomeVideoViewHolder viewHolder = (HomeVideoViewHolder) holder;
        HomeVideoBean bean = mList.get(position);
        if (mSelected == position) {
            viewHolder.icon.setImageResource(R.drawable.ad_ic_video_selected);
        } else {
            viewHolder.icon.setImageResource(R.drawable.ad_ic_video_no_selected);
        }
        viewHolder.content.setText(bean.getContent());
        long ts = 0;
        try {
            ts = dateFormat.parse(bean.getCreateTime()).getTime();
        } catch (ParseException e) {
            e.printStackTrace();
        }
        viewHolder.time.setText(timeFormat.format(ts));
        viewHolder.videoImage.setImageURI(bean.getFileUrl() + "?vframe/jpg/offset/1");

    }

    @Override
    public void onBindFooterViewHolder(@NonNull RecyclerView.ViewHolder holder, int currentFooterStatus) {
        FooterViewHolder footViewHolder = (FooterViewHolder) holder;
        switch (currentFooterStatus) {
            case UpLoadingRecyclerView.FooterStatus.FOOTER_PULL_UP_LOADING:
                footViewHolder.footerText.setText(R.string.ad_pull_up_load_more);
                footViewHolder.footerProgress.setVisibility(View.GONE);
                break;
            case UpLoadingRecyclerView.FooterStatus.FOOTER_LOADING:
                footViewHolder.footerText.setText(R.string.ad_loading_more_for_you);
                footViewHolder.footerProgress.setVisibility(View.VISIBLE);
                break;
            case UpLoadingRecyclerView.FooterStatus.FOOTER_ERROR:
                footViewHolder.footerText.setText(R.string.ad_network_anomaly_click_reload);
                footViewHolder.footerProgress.setVisibility(View.GONE);
                break;
            case UpLoadingRecyclerView.FooterStatus.FOOTER_NO_MORE_DATA:
                footViewHolder.footerText.setText(R.string.ad_Theres_nothing_more);
                footViewHolder.footerProgress.setVisibility(View.GONE);
                break;
        }

    }

    @Override
    public int getItemViewCount() {
        return mList.size();
    }

    public void setListener(OnClickListener listener) {
        this.mListener = listener;
    }

    public interface OnClickListener {
        void onClickItem(HomeVideoBean bean);

        void onClickFooter();

    }

    public static class HomeVideoViewHolder extends RecyclerView.ViewHolder {
        ImageView icon;
        TextView time;
        TextView content;
        SimpleDraweeView videoImage;

        public HomeVideoViewHolder(@NonNull View itemView) {
            super(itemView);
            icon = itemView.findViewById(R.id.icon);
            time = itemView.findViewById(R.id.time);
            content = itemView.findViewById(R.id.content);
            videoImage = itemView.findViewById(R.id.videoImage);
        }
    }

    public static class FooterViewHolder extends RecyclerView.ViewHolder {
        ProgressBar footerProgress;
        TextView footerText;

        public FooterViewHolder(@NonNull View itemView) {
            super(itemView);
            footerProgress = itemView.findViewById(R.id.footer_progress);
            footerText = itemView.findViewById(R.id.footer_text);
        }
    }
}

activity的关键部分

//数据来源
    mHomeVideoViewModel.getHomeVideoList().observe(this,new Observer<Result<List<HomeVideoBean>>>() {
        @Override
        public void onChanged (Result < List < HomeVideoBean >> result) {
            if (result.getCode() != 200 && result.getCode() != 0) { //服务器加载数据异常
                Toast.makeText(HomeVideoActivity.this, "" + result.getMsg(), Toast.LENGTH_SHORT).show();
                if (mCurrentPage == 1) { //如果是第一页数据就直接隐藏整个列表
                    mRecyclerMessageVideo.setVisibility(View.GONE);
                } else { //如果是其他页数据,就在页尾显示网络异常
                    mAdapter.setFooterNetWorkError();
                }
                return;
            }
            if (mCurrentPage == 1) { //如果页数等于1,那就是首次数据
                if (result.getData() != null && !result.getData().isEmpty()) {
                    mAdapter.refreshData(result.getData()); //刷新数据
                } else {
                    mRecyclerMessageVideo.setVisibility(View.GONE);
                }

            } else {
                mAdapter.addData(result.getData()); //添加数据
            }
            if (result.getData().size() < 10) { //判断获取的数据熟练是否满足10个达到一页内容
                mAdapter.setFooterNoMoreData(); //如果不满足,就显示没有更多数据了
            } else {
                mAdapter.setFooterPullUpLoading(); //如果满足,就显示上拉加载更多数据
            }
        }
    });
    mRecyclerMessageVideo.setOnUpPullLoadListener(new UpLoadingRecyclerView.OnUpPullLoadListener(){
      @Override
      public void OnUpPullLoad () { //上拉加载数据
        mAdapter.setFooterLoading(); //将尾页显示为加载中
        mCurrentPage++;
        mHomeVideoViewModel.postHomeVideoList(mRequestTime, mDeviceSn, mCurrentPage, 10); //请求数据

    }
    });
    mAdapter.setListener(new HomeVideoAdapter.OnClickListener(){
        @Override
        public void onClickItem (HomeVideoBean bean){
        　　//item点击

    }

        @Override
        public void onClickFooter () {
        　　if (mAdapter.isFooterNetWorkError()) { //如果尾页显示网络异常就允许点击,重新加载数据
            　　mHomeVideoViewModel.postHomeVideoList(mRequestTime, mDeviceSn, mCurrentPage, 10);
        　　}

    } });

End