在Android低版本中实现RecyclerView的分页加载 请写出代码

好的，以下是一个简单的实现RecyclerView分页加载的示例代码：

1. 在布局文件中添加RecyclerView控件和一个加载更多的进度条：

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:scrollbars="vertical"
    />

<ProgressBar
    android:id="@+id/progressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:visibility="gone"
    />

2. 创建一个RecyclerView的adapter，并在其中添加一个回调接口来通知主线程加载更多数据：

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

    private List<String> mData;
    private OnLoadMoreListener mOnLoadMoreListener;

    public MyAdapter(List<String> data) {
        mData = data;
    }

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

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // create a new view
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_layout, parent, false);
        // set the view's size, margins, paddings and layout parameters
        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        // bind data to the view
        ((ViewHolder) holder).mTextView.setText(mData.get(position));
        // check if we need to load more data
        if (position == getItemCount() - 1) {
            if (mOnLoadMoreListener != null) {
                mOnLoadMoreListener.onLoadMore();
            }
        }
    }

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

    public static class ViewHolder extends RecyclerView.ViewHolder {
        public TextView mTextView;

        public ViewHolder(View v) {
            super(v);
            mTextView = (TextView) v.findViewById(R.id.textView);
        }
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }
}

3. 在主Activity中，设置RecyclerView的adapter和LayoutManager，并在adapter中添加一个回调接口来加载更多数据：

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private ProgressBar mProgressBar;
    private MyAdapter mAdapter;
    private LinearLayoutManager mLayoutManager;
    private boolean mIsLoading = false;
    private int mTotalItemCount, mVisibleItemCount, mFirstVisibleItem, mVisibleThreshold = 5;

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

        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);
        mProgressBar = (ProgressBar) findViewById(R.id.progressBar);

        List<String> data = new ArrayList<>();
        for (int i = 0; i < 50; i++) {
            data.add("Item " + i);
        }

        mAdapter = new MyAdapter(data);
        mAdapter.setOnLoadMoreListener(new MyAdapter.OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                if (!mIsLoading) {
                    mIsLoading = true;
                    mProgressBar.setVisibility(View.VISIBLE);
                    // load more data here
                    new Handler().postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            for (int i = 0; i < 50; i++) {
                                mAdapter.mData.add("Item " + (mAdapter.getItemCount() + i));
                            }
                            mAdapter.notifyDataSetChanged();
                            mIsLoading = false;
                            mProgressBar.setVisibility(View.GONE);
                        }
                    }, 2000);
                }
            }
        });

        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mRecyclerView.setAdapter(mAdapter);

        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                mVisibleItemCount = mLayoutManager.getChildCount();
                mTotalItemCount = mLayoutManager.getItemCount();
                mFirstVisibleItem = mLayoutManager.findFirstVisibleItemPosition();

                if (!mIsLoading && mTotalItemCount <= (mFirstVisibleItem + mVisibleItemCount + mVisibleThreshold)) {
                    // load more data here
                    mAdapter.onLoadMore();
                    mIsLoading = true;
                }
            }
        });
    }
}

以上就是一个简单的RecyclerView分页加载的实现代码。注意：此示例仅供参考，具体实现可能需要根据实际情况进行调整和优化。