android 列表无限滚动

实现 Android 列表无限滚动的方法如下：

1. 实现一个继承自 RecyclerView.Adapter 的适配器类，重写 getItemViewType() 方法，根据当前位置返回不同的 ViewType。
2. 在 RecyclerView 的 LayoutManager 中重写 generateDefaultLayoutParams() 方法，设置高度为 WRAP_CONTENT。
3. 在 RecyclerView 的 OnScrollListener 中监听滚动事件，当滑动到列表底部时，加载更多数据并刷新列表。

具体代码实现可以参考以下示例：

public class MyAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
    private static final int TYPE_ITEM = 0;
    private static final int TYPE_LOADING = 1;

    private List<Item> mItemList;
    private boolean mIsLoading = false;

    public MyAdapter(List<Item> itemList) {
        mItemList = itemList;
    }

    @Override
    public int getItemViewType(int position) {
        return position < mItemList.size() ? TYPE_ITEM : TYPE_LOADING;
    }

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

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof ItemViewHolder) {
            ItemViewHolder itemViewHolder = (ItemViewHolder) holder;
            Item item = mItemList.get(position);
            // 绑定数据到 ItemViewHolder
        } else {
            LoadingViewHolder loadingViewHolder = (LoadingViewHolder) holder;
            // 显示正在加载的视图
        }
    }

    @Override
    public int getItemCount() {
        return mItemList.size() + (mIsLoading ? 1 : 0);
    }

    public void setLoading(boolean isLoading) {
        mIsLoading = isLoading;
        if (isLoading) {
            notifyItemInserted(getItemCount() - 1);
        } else {
            notifyItemRemoved(getItemCount() - 1);
        }
    }

    public static class ItemViewHolder extends RecyclerView.ViewHolder {
        // ItemViewHolder 中的视图
        public ItemViewHolder(View itemView) {
            super(itemView);
            // 初始化 ItemViewHolder 中的视图
        }
    }

    public static class LoadingViewHolder extends RecyclerView.ViewHolder {
        // LoadingViewHolder 中的视图
        public LoadingViewHolder(View itemView) {
            super(itemView);
            // 初始化 LoadingViewHolder 中的视图
        }
    }
}

public class MyLayoutManager extends LinearLayoutManager {
    private static final int VISIBLE_THRESHOLD = 5;

    private boolean mIsLoading = false;
    private OnLoadMoreListener mOnLoadMoreListener;

    public MyLayoutManager(Context context) {
        super(context);
    }

    public MyLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

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

    public void setLoading(boolean isLoading) {
        mIsLoading = isLoading;
    }

    @Override
    public RecyclerView.LayoutParams generateDefaultLayoutParams() {
        return new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    }

    @Override
    public void onScrolled(int dx, int dy) {
        super.onScrolled(dx, dy);
        if (!mIsLoading && getItemCount() - getChildCount() <= findFirstVisibleItemPosition() + VISIBLE_THRESHOLD) {
            setLoading(true);
            if (mOnLoadMoreListener != null) {
                mOnLoadMoreListener.onLoadMore();
            }
        }
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }
}

public class MyActivity extends AppCompatActivity {
    private RecyclerView mRecyclerView;
    private MyAdapter mAdapter;
    private MyLayoutManager mLayoutManager;

    private List<Item> mItemList = new ArrayList<>();

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

        mRecyclerView = findViewById(R.id.recycler_view);
        mAdapter = new MyAdapter(mItemList);
        mRecyclerView.setAdapter(mAdapter);
        mLayoutManager = new MyLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        mLayoutManager.setOnLoadMoreListener(new MyLayoutManager.OnLoadMoreListener() {
            @Override
            public void onLoadMore() {
                // 加载更多数据
                mAdapter.setLoading(false);
            }
        });

        // 初始加载数据
        mAdapter.notifyDataSetChanged();
    }
}