加载更多流程实现

mRecyclerView滑动到底部的监听

      mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                if (mCurrentState == ACTION_IDLE && isLoadMoreEnabled && checkIfLoadMore()) {
                    mCurrentState = ACTION_LOAD_MORE_REFRESH;
                    mSwipeRefreshLayout.setEnabled(false);
                    listener.onRefresh(ACTION_LOAD_MORE_REFRESH);
                }
            }
        });

checkIfLoadMore()

重点看一下checkIfLoadMore()这个方法，这个方法用来判断界面上最后一个位置和itemcount的比较，因为RecyclerView的LayoutManager有三种，这个如果用If else来进行判断，过于冗余，我们这个采用策略模式来进行编写。

public interface ILayoutManager {

    int findLastVisiblePosition();

    RecyclerView.LayoutManager getLayoutManager();
}


public class MyLinearLayoutManager extends LinearLayoutManager implements ILayoutManager {
    public MyLinearLayoutManager(Context context) {
        super(context);
    }

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

    public MyLinearLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }


    @Override
    public RecyclerView.LayoutManager getLayoutManager() {
        return this;
    }

    @Override
    public int findLastVisiblePosition() {
        return findLastVisibleItemPosition();
    }

}


 private boolean checkIfLoadMore() {

        int lastVisibleItemPosition = mLayoutManager.findLastVisiblePosition();
        int totalCount = mLayoutManager.getLayoutManager().getItemCount();
        return totalCount - lastVisibleItemPosition < 5;
    }

加载完成后

因为我们刷新和加载调用同一个接口，传递不同的参数，所以在操作完成后，我们需要进行判断，是哪种操作完成了
    public void onRefreshCompleted() {
        switch (mCurrentState) {
            case ACTION_PULL_TO_REFRESH:
                mSwipeRefreshLayout.setRefreshing(false);

                break;
            case ACTION_LOAD_MORE_REFRESH:
                if (isPullToRefreshEnabled) {
                    mSwipeRefreshLayout.setEnabled(true);
                }

                break;
            default:
                break;
        }
        mCurrentState = ACTION_IDLE;
    }