flutter_fulltime_recruiter/lib/comm/widget/my_refresh_list.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:ftrecruiter/comm/utils/dark_theme_util.dart';

/// 封装下拉刷新与加载更多
class MyRefreshListView extends StatefulWidget {
  const MyRefreshListView({
    Key? key,
    required this.itemCount,
    required this.itemBuilder,
    this.onRefresh,
    this.loadMore,
    this.hasMore = false,
    this.pageSize = 10,
    this.padding,
    this.itemExtent,
  }) : super(key: key);

  final RefreshCallback? onRefresh;
  final LoadMoreCallback? loadMore;
  final int itemCount;
  final bool hasMore;
  final IndexedWidgetBuilder itemBuilder;

  /// 一页的数量，默认为10
  final int pageSize;

  /// padding属性使用时注意会破坏原有的SafeArea，需要自行计算bottom大小
  final EdgeInsetsGeometry? padding;
  final double? itemExtent;

  @override
  _MyRefreshListViewState createState() => _MyRefreshListViewState();
}

typedef RefreshCallback = Future<void> Function();
typedef LoadMoreCallback = Future<void> Function();

class _MyRefreshListViewState extends State<MyRefreshListView> {
  /// 是否正在加载数据
  bool _isLoading = false;

  @override
  Widget build(BuildContext context) {
    //刷新布局包裹-系统的刷新布局
    final Widget child = widget.onRefresh == null
        ? ListView.builder(
            itemCount: widget.loadMore == null ? widget.itemCount : widget.itemCount + 1,
            padding: widget.padding,
            itemExtent: widget.itemExtent,
            itemBuilder: (BuildContext context, int index) {
              /// 不需要加载更多则不需要添加FootView
              if (widget.loadMore == null) {
                return widget.itemBuilder(context, index);
              } else {
                return index < widget.itemCount
                    ? widget.itemBuilder(context, index)
                    : MoreWidget(widget.itemCount, widget.hasMore, widget.pageSize);
              }
            },
          )
        : RefreshIndicator(
            onRefresh: widget.onRefresh!,
            child: widget.itemCount == 0
                ? const SizedBox()
                : ListView.builder(
                    itemCount: widget.loadMore == null ? widget.itemCount : widget.itemCount + 1,
                    padding: widget.padding,
                    itemExtent: widget.itemExtent,
                    itemBuilder: (BuildContext context, int index) {
                      /// 不需要加载更多则不需要添加FootView
                      if (widget.loadMore == null) {
                        return widget.itemBuilder(context, index);
                      } else {
                        return index < widget.itemCount
                            ? widget.itemBuilder(context, index)
                            : MoreWidget(widget.itemCount, widget.hasMore, widget.pageSize);
                      }
                    },
                  ),
          );

    //返回真正的布局-监听LoadMore
    return SafeArea(
      child: NotificationListener<ScrollNotification>(
        onNotification: (ScrollNotification note) {
          /// 确保是垂直方向滚动，且滑动至底部
          if (note.metrics.pixels == note.metrics.maxScrollExtent && note.metrics.axis == Axis.vertical) {
            _loadMore();
          }
          return true;
        },
        child: child,
      ),
    );
  }

  Future<void> _loadMore() async {
    if (widget.loadMore == null) {
      return;
    }
    if (_isLoading) {
      return;
    }
    if (!widget.hasMore) {
      return;
    }
    _isLoading = true;
    await widget.loadMore?.call();
    _isLoading = false;
  }
}

//LoadMore-底部加载更多的布局
class MoreWidget extends StatelessWidget {
  const MoreWidget(this.itemCount, this.hasMore, this.pageSize, {Key? key}) : super(key: key);

  final int itemCount;
  final bool hasMore;
  final int pageSize;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 50,
      alignment:Alignment.center ,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          if (hasMore) const CupertinoActivityIndicator(),
          if (hasMore)
            const SizedBox(
              width: 5,
            ),

          // 只有一页的时候，就不显示FooterView了
          Text(hasMore ? '正在加载中...' : (itemCount < pageSize ? '' : '没有了呦~'),
              style: TextStyle(
                  fontSize: 14, color: DarkThemeUtil.multiColors(const Color(0x8A000000), darkColor: Colors.white54))),
        ],
      ),
    );
  }
}