项目需求讨论 - RecycleView 分页加载实现分析

public class BaseLoadAdapter<T> extends RecyclerView.Adapter {

    public List<T> list;
    public static final int TYPE_OTHER = 1;
    public static final int TYPE_BOTTOM = 2;

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        if (TYPE_BOTTOM == viewType) {
            //返回我们的那个加载中的布局Viewholder
            return new NewBottomViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_footer_new, parent, false));
        } else {
            //返回我们的交易记录的布局Viewholder
            return new MyViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.item_transferexam_info, parent, false));
        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (getItemViewType(position) == TYPE_BOTTOM) {
            //对相应的onBindViewHolder进行处理
            LinearLayout container = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).container;
            final ProgressBar pb = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).pb;
            final TextView content = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).content;

            .................
            .................
            .................
        } else {
            //对具体的交易记录的itemView进行相应的控件进行处理。
            TransferExamItemBean bean = ((TransferExamItemBean) list.get(position));
            holder.itemView.setTag(bean);
            ((ExamRefreshAdapter.MyViewHolder) holder).name.setText(bean.getToCompanyName());
            ((ExamRefreshAdapter.MyViewHolder) holder).date.setText(bean.getCreateDate());
            ((ExamRefreshAdapter.MyViewHolder) holder).money.setText(bean.getAmount()+"");
        }
    }

    @Override
    public int getItemCount() {
        return list.size() < 4 ? list.size() : list.size() + 1;
    }

    @Override
    public int getItemViewType(int position) {
        if (!list.isEmpty() && list.size() < position ) {
            return TYPE_OTHER;
        } else {
            return TYPE_BOTTOM;
        }
    }
}

public class LoadMoreScrollListener etends RecyclerView.OnScrollListener {

    private RecyclerView mRecyclerView;

    public LoadMoreScrollListener(RecyclerView recyclerView) {
        this.mRecyclerView = recyclerView;
    }

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

        RecyclerView.LayoutManager manager = mRecyclerView.getLayoutManager();
        BaseLoadMoreAdapter adapter = (BaseLoadMoreAdapter) mRecyclerView.getAdapter();

        if (null == manager) {
            throw new RuntimeException("you should call setLayoutManager() first!!");
        }
        if (manager instanceof LinearLayoutManager) {
            int lastCompletelyVisibleItemPosition = ((LinearLayoutManager) manager).findLastCompletelyVisibleItemPosition();

            if (adapter.getItemCount() > 4 &&
                    lastCompletelyVisibleItemPosition == adapter.getItemCount() - 1 &&
                    adapter.isHasMore()) {

                adapter.isLoadingMore();

            }
        }
    }
}

public int loadState;
int STATE_LOADING = 1;
int STATE_LASTED = 2;
int STATE_ERROR = 3;

public final void isLoadingMore() {
        if (loadState == STATE_LOADING) {
            return;
        }
        loadState = STATE_LOADING;
        notifyItemRangeChanged(getItemRealCount(), 1);
}

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (getItemViewType(position) == TYPE_BOTTOM) {
            //对相应的onBindViewHolder进行处理
            LinearLayout container = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).container;
            final ProgressBar pb = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).pb;
            final TextView content = ((BaseLoadMoreAdapter.NewBottomViewHolder) holder).content;


           //根据不同state来进行相应处理
            switch (loadState) {
                //1.当state是STATE_LOADING，
                //那我们就知道要把最后一项的字变为“加载中”
                //并且要让我写在布局中的滚动条进行显示(一般在加载中才会有滚动条的显示)
                //这时候调用我们的自定义方法loadMoreListener.onLoadMore();方法，这个方法是用来访问后台接口，然后去获取数据的。
                case AdapterLoader.STATE_LOADING:
                    content.setText("加载中");
                    container.setOnClickListener(null);
                    pb.setVisibility(View.VISIBLE);
                    if (loadMoreListener != null) {
                        loadMoreListener.onLoadMore();
                    }

                    break;

                //2.当state是STATE_LASTED的时候
                //最后一项的字变为“没有更多了”
                //我们的加载进度条也可以隐藏了
                case AdapterLoader.STATE_LASTED:
                    pb.setVisibility(View.GONE);       
                    container.setOnClickListener(null);
                    content.setText("---  没有更多了  ---");

                    //大家还记不记得我们在监听滑动的时候，我们有个adapter.isHasMore()变量作为控制，
                    //当我们的状态已经变为了STATE_LASTED了。那我们也不需要再监听是否滑到了最底部了。因为已经加载全部了。
                    adapter.setHasMore(false);

                    break;


                //3.当state是STATE_ERROR的时候
                //最后一项的字变为“加载更多失败点击重试”
                //我们的加载进度条也可以隐藏了
                //这里会跟其他二个状态不同的地方，那就是当加载失败的时候，我们可以通过点击这项，再去重新加载。
                //所以就要在最后一项中添加一个点击事件。所以在其他二个状态下，要重新设置setOnClickListener(null),来取消这个重新加载的点击事件。
                case AdapterLoader.STATE_ERROR:
                    pb.setVisibility(View.GONE);
                    content.setText("--- 加载更多失败点击重试 ---");
                    container.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            if (loadMoreListener != null) {
                                loadMoreListener.onLoadMore();
                            }
                            content.setText("加载中");
                            pb.setVisibility(View.VISIBLE);
                        }
                    });

                    break;
                default:
                    break;
            }

        } else {
            //对具体的交易记录的itemView进行相应的控件进行处理。
            TransferExamItemBean bean = ((TransferExamItemBean) list.get(position));
            holder.itemView.setTag(bean);
            ((ExamRefreshAdapter.MyViewHolder) holder).name.setText(bean.getToCompanyName());
            ((ExamRefreshAdapter.MyViewHolder) holder).date.setText(bean.getCreateDate());
            ((ExamRefreshAdapter.MyViewHolder) holder).money.setText(bean.getAmount()+"");
        }
    }

public final void appendList(List<T> data) {
        int positionStart = list.size();
        list.addAll(data);
        int itemCount = list.size() - positionStart;

        if (positionStart == 0) {
            notifyDataSetChanged();
        } else {
            notifyItemRangeInserted(positionStart + 1, itemCount);
        }
    }

public void onLoadMore() {
        if (isRun) {
            return;
        }
        isRun = true;
        presenter.getTransferExamList("zjzt", lastOrderID);
    }