recyclerview分页加载显示

RecyclerView 分页加载显示可以通过以下步骤实现：

1. 在 RecyclerView 中设置一个滚动监听（OnScrollListener），以便在滚动过程中检测是否需要加载更多数据。

2. 定义一个接口（OnLoadMoreListener），当 RecyclerView 滚动到底部时会调用这个接口的方法，以便在这个方法中加载更多数据。

3. 在 RecyclerView 的适配器中添加一个 Loading View，用于显示正在加载的状态。

4. 当需要加载更多数据时，显示 Loading View，并调用 OnLoadMoreListener 接口的方法来加载更多数据。

5. 加载完成后，隐藏 Loading View，并更新 RecyclerView 的数据集。

以下是一个简单的示例代码：

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private final int VIEW_TYPE_ITEM = 0;
    private final int VIEW_TYPE_LOADING = 1;

    private List<MyData> mDataList;
    private OnLoadMoreListener mOnLoadMoreListener;
    private boolean mIsLoading = false;

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
        mOnLoadMoreListener = onLoadMoreListener;
    }

    @Override
    public int getItemViewType(int position) {
        return mDataList.get(position) == null ? VIEW_TYPE_LOADING : VIEW_TYPE_ITEM;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == VIEW_TYPE_LOADING) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_loading, parent, false);
            return new LoadingViewHolder(view);
        } else {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_data, parent, false);
            return new DataViewHolder(view);
        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof DataViewHolder) {
            MyData data = mDataList.get(position);
            ((DataViewHolder) holder).bindData(data);
        } else if (holder instanceof LoadingViewHolder) {
            ((LoadingViewHolder) holder).showLoading();
            if (!mIsLoading && mOnLoadMoreListener != null) {
                mIsLoading = true;
                mOnLoadMoreListener.onLoadMore();
            }
        }
    }

    @Override
    public int getItemCount() {
        return mDataList.size();
    }

    public void setData(List<MyData> dataList) {
        mDataList = dataList;
        notifyDataSetChanged();
    }

    public void addData(List<MyData> dataList) {
        mDataList.addAll(dataList);
        notifyDataSetChanged();
        mIsLoading = false;
    }

    public static class DataViewHolder extends RecyclerView.ViewHolder {

        private TextView mTextView;

        public DataViewHolder(View itemView) {
            super(itemView);
            mTextView = itemView.findViewById(R.id.text_view);
        }

        public void bindData(MyData data) {
            mTextView.setText(data.getText());
        }
    }

    public static class LoadingViewHolder extends RecyclerView.ViewHolder {

        private ProgressBar mProgressBar;

        public LoadingViewHolder(View itemView) {
            super(itemView);
            mProgressBar = itemView.findViewById(R.id.progress_bar);
        }

        public void showLoading() {
            mProgressBar.setVisibility(View.VISIBLE);
        }
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }
}

在 Activity 或 Fragment 中，你需要设置 RecyclerView 的 LayoutManager 和 Adapter，并在 Adapter 中设置 OnLoadMoreListener 接口。

public class MyFragment extends Fragment implements MyAdapter.OnLoadMoreListener {

    private RecyclerView mRecyclerView;
    private MyAdapter mAdapter;
    private LinearLayoutManager mLayoutManager;
    private List<MyData> mDataList = new ArrayList<>();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_my, container, false);
        mRecyclerView = view.findViewById(R.id.recycler_view);
        mAdapter = new MyAdapter();
        mAdapter.setOnLoadMoreListener(this);
        mLayoutManager = new LinearLayoutManager(getActivity());
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);
        loadData();
        return view;
    }

    private void loadData() {
        // load data from server or database
        // add the loaded data to mDataList
        mAdapter.setData(mDataList);
    }

    @Override
    public void onLoadMore() {
        // load more data from server or database
        // add the loaded data to mDataList
        mAdapter.addData(mDataList);
    }
}

这样，当用户滑动到 RecyclerView 的底部时，就会触发 onLoadMore() 方法来加载更多数据。同时，RecyclerView 会自动显示 Loading View 来提示用户正在加载数据。