flutter中的网络请求和下拉刷新上拉加载，toast的案例

import ‘package:flutter/cupertino.dart‘;
import ‘package:flutter/material.dart‘;
import ‘package:futuredemo/log_utils.dart‘;
import ‘package:futuredemo/toast_utils.dart‘;
import ‘./page_error.dart‘;
import ‘./page_loading.dart‘;
import ‘package:pull_to_refresh/pull_to_refresh.dart‘;
import ‘BaseNetResponseModel.dart‘;
import ‘NetDataRepository.dart‘;
import ‘databean.dart‘;

class JobPage extends StatefulWidget {
  @override
  _JobPageState createState() => _JobPageState();
}


class _JobPageState extends State<JobPage> {
  NetDataRepository _netDataRepository = NetDataRepository();
  
  Future<Map<String, dynamic>> _futureBuilderFuture;
  List<DataBean> dataList = List();

  RefreshController _refreshController =
      RefreshController(initialRefresh: false);

  void initState() {
    super.initState();

    _futureBuilderFuture = _loadData();
  }

  void _onRefresh() async {
    BaseNetResponseModel<List<DataBean>> model =
        await _netDataRepository.getUserAll("1", "10");
    dataList.clear();
    dataList.addAll(model.data);
    // 日志打印
    LogUtils.d("tag", model.code);
    _refreshController.refreshCompleted();
    _refreshController.loadComplete();
    if (mounted) setState(() {});
  }

  void _onLoading() async {
    await Future.delayed(Duration(milliseconds: 1000));
    if (dataList.length < 30) {
      dataList.add(dataList[0]);
    } else {
      _refreshController.loadNoData();
      return;
    }

    if (mounted) setState(() {});

    _refreshController.loadComplete();
  }

  Future<Map<String, dynamic>> _loadData() async {
    BaseNetResponseModel<List<DataBean>> model =
        await _netDataRepository.getUserAll("1", "10");
    dataList.clear();
    dataList.addAll(model.data);
    return {"data": 0};
  }

  _refresh() async {
    setState(() {
      _futureBuilderFuture = _loadData();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
  
      appBar: AppBar(
        elevation: 0.0,
        title: Text(‘职业‘),
        centerTitle: true,
      ),
      floatingActionButton: FloatingActionButton(
          backgroundColor: Theme.of(context).primaryColor,
          child: Icon(
            Icons.add,
            size: 28,
            color: Colors.white,
          ),
          elevation: 4,
          onPressed: () {
            //吐司提示
            ToastUtils.toastShort("点击了");
          }),
      body: FutureBuilder(
        builder: (BuildContext context,
            AsyncSnapshot<Map<String, dynamic>> snapshot) {
          Widget widget;
          switch (snapshot.connectionState) {
            case ConnectionState.none:
              widget = Container();
              break;
            case ConnectionState.active:
            case ConnectionState.waiting:
              widget = PageLoading();
              break;
            case ConnectionState.done:
              if (snapshot.hasError) {
                widget = PageError(
                  callback: _refresh,
                );
              } else if (snapshot.hasData) {
                widget = _buildBody(context);
              }
              break;
          }
          return widget;
        },
        future: _futureBuilderFuture,
      ),
    );
  }

  Column _buildBody(BuildContext context) {
    return Column(
      children: <Widget>[
        Expanded(
          child: SmartRefresher(
            enablePullDown: true,
            enablePullUp: true,
            header: WaterDropMaterialHeader(
                // backgroundColor:Color(OxFF00),
                ),
            footer: CustomFooter(
              builder: (BuildContext context, LoadStatus mode) {
                Widget body;
                if (mode == LoadStatus.idle) {
                  body = Row(children: <Widget>[
                    Expanded(
                      flex: 3,
                      child: Divider(
                        indent: 40,
                        height: 1,
                      ),
                    ),
                    Expanded(
                      flex: 2,
                      child: Container(
                        height: 40.0,
                        child: Center(
                            child: Text("上拉加载更多",
                                style: TextStyle(
                                    color: Colors.grey, fontSize: 13))),
                      ),
                    ),
                    Expanded(
                      flex: 3,
                      child: Divider(
                        height: 1,
                        endIndent: 40,
                      ),
                    )
                  ]);
                } else if (mode == LoadStatus.loading) {
                  body = CupertinoActivityIndicator();
                } else if (mode == LoadStatus.failed) {
                  body = Text("加载失败！",
                      style: TextStyle(color: Colors.grey, fontSize: 13));
                } else {
                  body = Row(children: <Widget>[
                    Expanded(
                      flex: 3,
                      child: Divider(
                        indent: 40,
                        height: 1,
                      ),
                    ),
                    Expanded(
                      flex: 2,
                      child: Container(
                        height: 40.0,
                        child: Center(
                            child: Text("已经到底啦",
                                style: TextStyle(
                                    color: Colors.grey, fontSize: 13))),
                      ),
                    ),
                    Expanded(
                      flex: 3,
                      child: Divider(
                        height: 1,
                        endIndent: 40,
                      ),
                    )
                  ]);
                }
                return Container(
                  height: 50.0,
                  child: Center(child: body),
                );
              },
            ),
            controller: _refreshController,
            onRefresh: _onRefresh,
            onLoading: _onLoading,
            child: GridView.builder(
                padding: EdgeInsets.all(10.0),
                shrinkWrap: true,
                itemCount: dataList.length,
                gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                    crossAxisCount: 2,
                    //纵轴间距
                    mainAxisSpacing: 10.0,
                    //横轴间距
                    crossAxisSpacing: 10.0,
                    //子组件宽高长度比例
                    childAspectRatio: 1.5),
                itemBuilder: (context, index) {
                  // Map<String, dynamic> entry = dataList[index];
                  return UserItemWidget(
                    title: ‘${dataList[index].job}‘,
                    onTap: () {},
                  );
                }),
          ),
        ),
      ],
    );
  }
}

class UserItemWidget extends StatefulWidget {
  String title = "";

  int type = 1;
  VoidCallback onTap;

  UserItemWidget({
    Key key,
    this.title,
    this.onTap,
  }) : super(key: key);

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

class _UserItemWidgetState extends State<UserItemWidget> {
  VoidCallback _onTap;

  @override
  void initState() {
    super.initState();
    _onTap = widget.onTap;
  }

  @override
  Widget build(BuildContext context) {
    return InkWell(
      onTap: _onTap,
      child: Stack(
        children: <Widget>[
          Container(
            padding: EdgeInsets.all(8),
            decoration: new BoxDecoration(
              color: Colors.white,
              border: new Border.all(width: 1.0, color: Colors.grey[300]),
              borderRadius: new BorderRadius.all(new Radius.circular(2)),
            ),
            child: Column(
              mainAxisSize: MainAxisSize.max,
              children: <Widget>[
                Container(
                  margin: EdgeInsets.only(top: 15, bottom: 10, left: 10),
                  alignment: Alignment.centerLeft,
                  child: Text(widget.title == "" ? "未知" : widget.title,
                      style: TextStyle(fontSize: 18)),
                ),
              ],
            ),
          ),
          Positioned(
              top: 0,
              right: 0,
              child: Container(
                color: getTypeColor(widget.type),
                padding: EdgeInsets.all(5),
                child: Center(
                  child: Text(getTypeText(widget.type),
                      style: TextStyle(
                        color: Colors.white,
                        fontSize: 13.0,
                      )),
                ),
              ))
        ],
      ),
    );
  }

  String getTypeText(int type) {
    switch (type) {
      case 1:
        return "黄金职业";
      case 2:
        return "夕阳职业";
      case 3:
        return "朝阳职业";
    }
  }

  Color getTypeColor(int type) {
    switch (type) {
      case 1:
        return Color(0xFFFF00FF);
      case 2:
        return Color(0xFFC6C6C6);
      case 3:
        return Color(0xFF7FC3FD);
    }
  }
}