ListView加载更多的最简单实现方式

た入场券 2022-07-17 02:16 158阅读 0赞

public class RefreshListView extends ListView implements AbsListView.OnScrollListener {
        public RefreshListView(Context context) {
            this(context,null);
        }
        public RefreshListView(Context context, AttributeSet attrs) {
            super(context, attrs);
            this.setOnScrollListener(this);
            TextView textView = new TextView(context);
            textView.setGravity(Gravity.CENTER);
            textView.setHeight(DensityUtils.dp2px(context,50));
            textView.setText("加载更多中...");
            this.addFooterView(textView);
        }
        
        @Override
        protected void onScrollChanged(int l, int t, int oldl, int oldt) {
            super.onScrollChanged(l, t, oldl, oldt);
        }
        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
        }
    
        RefreshingCallback loadMore;
        boolean isLoadingMore = false;
        public void  setLoadMore(RefreshingCallback loadMore){
            this.loadMore = loadMore;
        }
    
        public void notifyLoadMoreFinished(){
            isLoadingMore = false;
        }
    
    
        public void onScroll(AbsListView view, int firstVisibleItem,
                             int visibleItemCount, int totalItemCount) {
           // LogUtil.v("=onScroll======visibleItemCount:"+visibleItemCount+" firstVisibleItem:"+firstVisibleItem+" totalItemCount:"+totalItemCount);
            if(firstVisibleItem+visibleItemCount==totalItemCount&&!isLoadingMore&&firstVisibleItem!=0){
                if(loadMore!=null) {
                            isLoadingMore = true;
                            loadMore.startLoadMore();
                }
            }
        }
    
        public interface RefreshingCallback{
            void startLoadMore();
        }
    }

需要注意的是：因为List加了个footer所以此处最后一个条目会返回null

@Override
    public Object getItem(int position) {
        if(list.size()>position){
            return list.get(position);
        }
       return null; //Bug
    }这里面还有一点需要自己注意：就是当没有网络的时候，此处会一直处于：  isLoadingMore = true; 状态。除非再次初始化。 建议：可以在网络请求失败后做通知ListView还原的处理  isLoadingMore = false;