12 Flutter仿京东商城项目 商品列表页面请求数据、封装Loading Widget、上拉分页加载更多

ProductList.dart

import 'package:flutter/material.dart';
import '../services/ScreenAdaper.dart';
import '../config/Config.dart';
import 'package:dio/dio.dart';
import '../model/ProductModel.dart';
import '../widget/LoadingWidget.dart';

class ProductListPage extends StatefulWidget {
  Map arguments;
  ProductListPage({Key key, this.arguments}) : super(key: key);

  _ProductListPageState createState() => _ProductListPageState();
}

class _ProductListPageState extends State<ProductListPage> {
  //通过事件打开侧边栏，需要全局声明一下：
  final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
  //配置下拉加载更多：
  ScrollController _scrollController = ScrollController();
  //分页：
  int _page = 1;
  //每一页有多少条数据：
  int _pageSize = 10;
  //分页：
  List _productList = [];
  //排序：
  String _sort = "";
  //解决重复请求的问题：
  bool flag = true;

  //是否有数据：
  bool _hasMore = true;

  //初始化的时候获取的生命周期函数：
  @override
  void initState() {
    super.initState();
    _getProductListData();
    //监听滚动条滚动事件：
    _scrollController.addListener(() {
      // _scrollController.position.pixels //获取滚动条滚动高度
      // _scrollController.position.maxScrollExtent //获取页面滚动高度：
      if (_scrollController.position.pixels >
          _scrollController.position.maxScrollExtent - 20) {
        if (this.flag&&this._hasMore) {
          _getProductListData();
        }
      }
    });
  }

  //获取商品列表的数据：
  _getProductListData() async {
    setState(() {
      this.flag = false;
    });
    var api =
        '${Config.domain}api/plist?cid=${widget.arguments["cid"]}&page=${_page}&sort=${this._sort}&pageSize=${_pageSize}';
    var result = await Dio().get(api);
    var productList = ProductModel.fromJson(result.data);
    print(productList.result);

    if (productList.result.length < this._pageSize) {
      setState(() {
        this._productList.addAll(productList.result);
        this._hasMore = false;
        this.flag = true;
        // this._productList = productList.result;
      });
    } else {
      setState(() {
        this._productList.addAll(productList.result);
        this._page++;
        this.flag = true;
        // this._productList = productList.result;
      });
    }
  }
  //显示加载中的圈圈：
  Widget _showMore(index){
    if(this._hasMore){
      return (index == this._productList.length - 1)? LoadingWidget() : Text('');
    }else{
      return (index == this._productList.length - 1)? Text("---暂无其他数据了--") : Text('');
    }
  }

  //商品列表：
  Widget _productListWidget() {
    if (this._productList.length > 0) {
      return Container(
        padding: EdgeInsets.all(10),
        margin: EdgeInsets.only(top: ScreenAdaper.height(80)),
        child: ListView.builder(
          controller: _scrollController,
          itemBuilder: (context, index) {
            //处理图片：
            String pic = this._productList[index].pic;
            pic = Config.domain + pic.replaceAll('\', '/');
            //获得每一个元素：
            return Column(
              children: <Widget>[
                Row(
                  children: <Widget>[
                    Container(
                       ScreenAdaper.width(180),
                      height: ScreenAdaper.height(180),
                      child: Image.network("${pic}", fit: BoxFit.cover),
                    ),
                    Expanded(
                      flex: 1,
                      child: Container(
                        height: ScreenAdaper.height(180),
                        margin: EdgeInsets.only(left: 10),
                        // color: Colors.red,
                        child: Column(
                          mainAxisAlignment: MainAxisAlignment.spaceBetween,
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: <Widget>[
                            Text(
                              "${this._productList[index].title}",
                              maxLines: 2,
                              overflow: TextOverflow.ellipsis,
                            ),
                            Row(
                              children: <Widget>[
                                Container(
                                  height: ScreenAdaper.height(36),
                                  margin: EdgeInsets.only(right: 10),
                                  padding: EdgeInsets.fromLTRB(10, 0, 10, 0),
                                  //注意：如果Container里面加上decoration属性，这个时候color属性必须放到BoxDecoration
                                  decoration: BoxDecoration(
                                    borderRadius: BorderRadius.circular(10),
                                    // color:Color.fromRGBO(230, 230, 230, 0.9)
                                  ),
                                  child: Text('4G'),
                                ),
                                Container(
                                  height: ScreenAdaper.height(36),
                                  margin: EdgeInsets.only(right: 10),
                                  padding: EdgeInsets.fromLTRB(10, 0, 10, 0),
                                  //注意：如果Container里面加上decoration属性，这个时候color属性必须放到BoxDecoration
                                  decoration: BoxDecoration(
                                    borderRadius: BorderRadius.circular(10),
                                    // color:Color.fromRGBO(230, 230, 230, 0.3)
                                  ),
                                  child: Text('16G'),
                                )
                              ],
                            ),
                            Text("￥ ${this._productList[index].price}",
                                style:
                                    TextStyle(color: Colors.red, fontSize: 16))
                          ],
                        ),
                      ),
                    )
                  ],
                ),
                Divider(
                  height: 20,
                ),
                this._showMore(index)
              ],
            );
          },
          itemCount: this._productList.length,
        ),
      );
    } else {
      return LoadingWidget();
    }
  }

  //筛选导航：
  Widget _subHeaderWidget() {
    return Positioned(
      top: 0,
      height: ScreenAdaper.height(80),
       ScreenAdaper.width(750),
      child: Container(
        height: ScreenAdaper.height(80),
         ScreenAdaper.width(750),
        // color: Colors.red,
        decoration: BoxDecoration(
            border: Border(
                bottom: BorderSide(
                     1, color: Color.fromRGBO(233, 233, 233, 0.9)))),
        child: Row(
          children: <Widget>[
            Expanded(
              flex: 1,
              child: InkWell(
                child: Padding(
                  padding: EdgeInsets.fromLTRB(
                      0, ScreenAdaper.height(20), 0, ScreenAdaper.height(20)),
                  child: Text(
                    '综合',
                    textAlign: TextAlign.center,
                    style: TextStyle(color: Colors.red),
                  ),
                ),
                onTap: () {},
              ),
            ),
            Expanded(
              flex: 1,
              child: InkWell(
                child: Padding(
                  padding: EdgeInsets.fromLTRB(
                      0, ScreenAdaper.height(20), 0, ScreenAdaper.height(20)),
                  child: Text('销量', textAlign: TextAlign.center),
                ),
                onTap: () {},
              ),
            ),
            Expanded(
              flex: 1,
              child: InkWell(
                child: Padding(
                  padding: EdgeInsets.fromLTRB(
                      0, ScreenAdaper.height(20), 0, ScreenAdaper.height(20)),
                  child: Text('价格', textAlign: TextAlign.center),
                ),
                onTap: () {},
              ),
            ),
            Expanded(
              flex: 1,
              child: InkWell(
                child: Padding(
                  padding: EdgeInsets.fromLTRB(
                      0, ScreenAdaper.height(20), 0, ScreenAdaper.height(20)),
                  child: Text('筛选', textAlign: TextAlign.center),
                ),
                onTap: () {
                  _scaffoldKey.currentState.openEndDrawer();
                },
              ),
            )
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    ScreenAdaper.init(context);
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: Text('商品列表'),
        actions: <Widget>[Text('')],
      ),
      endDrawer: Drawer(
        child: Container(
          child: Text('实现筛选功能'),
        ),
      ),
      // body: Text("${widget.arguments}"),
      body: Stack(
        children: <Widget>[_productListWidget(), _subHeaderWidget()],
      ),
    );
  }
}

Category.dart

import 'package:flutter/material.dart';
import '../../services/ScreenAdaper.dart';
import '../../config/Config.dart';
import 'package:dio/dio.dart';
import '../../model/CateModel.dart';

class CategoryPage extends StatefulWidget {
  CategoryPage({Key key}) : super(key: key);

  _CategoryPageState createState() => _CategoryPageState();
}

class _CategoryPageState extends State<CategoryPage>
    with AutomaticKeepAliveClientMixin {
  int _selectIndex = 0;
  List _leftCateList = [];
  List _rightCateList = [];
  @override
  // TODO: implement wantKeepAlive
  bool get wantKeepAlive => true;
  @override
  void initState() {
    super.initState();
    _getLeftCateData();
  }

  //左侧数据：
  _getLeftCateData() async {
    var api = '${Config.domain}api/pcate';
    var result = await Dio().get(api);
    var leftCateList = CateModel.fromJson(result.data);
    setState(() {
      this._leftCateList = leftCateList.result;
    });
    _getRightCateData(leftCateList.result[0].sId);
  }

  //右侧数据：
  _getRightCateData(pid) async {
    var api = '${Config.domain}api/pcate?pid=${pid}';
    var result = await Dio().get(api);
    var rightCateList = CateModel.fromJson(result.data);
    print(6666);
    setState(() {
      this._rightCateList = rightCateList.result;
    });
  }

  //左侧组件
  Widget _leftCateWidget(leftWidth) {
    if (this._leftCateList.length > 0) {
      return Container(
         leftWidth,
        height: double.infinity,
        // color: Colors.red,
        child: ListView.builder(
          itemCount: this._leftCateList.length,
          itemBuilder: (context, index) {
            return Column(
              children: <Widget>[
                InkWell(
                  onTap: () {
                    setState(() {
                      // setState(() {
                      _selectIndex = index;
                      this._getRightCateData(this._leftCateList[index].sId);
                    });
                    print(_selectIndex);
                  },
                  child: Container(
                     double.infinity,
                    height: ScreenAdaper.height(56),
                    padding: EdgeInsets.only(top: ScreenAdaper.height(24)),
                    child: Text("${this._leftCateList[index].title}",
                        textAlign: TextAlign.center),
                    color: _selectIndex == index
                        ? Color.fromRGBO(240, 246, 246, 0.9)
                        : Colors.white,
                  ),
                ),
                Divider(height: 1),
              ],
            );
          },
        ),
      );
    } else {
      return Container(
         leftWidth,
        height: double.infinity,
      );
    }
  }

  //右侧组件：
  Widget _rightCateWidget(rightItemWidth, rightItemHeigth) {
    if (this._rightCateList.length > 0) {
      return Expanded(
        flex: 1,
        child: Container(
          padding: EdgeInsets.all(10),
          height: double.infinity,
          color: Color.fromRGBO(240, 246, 246, 0.9),
          // color: Colors.blue,
          child: GridView.builder(
            gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: 3,
                childAspectRatio: rightItemWidth / rightItemHeigth,
                crossAxisSpacing: 10,
                mainAxisSpacing: 10),
            itemCount: this._rightCateList.length,
            itemBuilder: (context, index) {
              //处理图片：
              String pic = this._rightCateList[index].pic;
              pic = Config.domain + pic.replaceAll('\', '/');
              return InkWell(
                  child: Container(
                    // padding: EdgeInsets.all(ScreenAdaper.width(20)),
                    child: Column(
                      children: <Widget>[
                        AspectRatio(
                          aspectRatio: 1 / 1,
                          child: Image.network("${pic}", fit: BoxFit.cover),
                        ),
                        Container(
                          height: ScreenAdaper.height(32),
                          child: Text("${this._rightCateList[index].title}"),
                        )
                      ],
                    ),
                  ),
                  onTap: (){
                    Navigator.pushNamed(context,'/productList',arguments: {
                      "cid":this._rightCateList[index].sId
                    });
                  },

              );
            },
          ),
        ),
      );
    } else {
      return Expanded(
          flex: 1,
          child: Container(
            padding: EdgeInsets.all(10),
            height: double.infinity,
            color: Color.fromRGBO(240, 246, 246, 0.9),
            child: Text('加载中...'),
          ));
    }
  }

  Widget build(BuildContext context) {
    ScreenAdaper.init(context);

    //计算右侧GridView宽高比：
    var leftWidth = ScreenAdaper.getScreenWidth() / 4;
    //右侧宽高=总宽度-左侧宽度-Gridview外层元素左右的Padding值-GridView中间的间距
    var rightItemWidth =
        (ScreenAdaper.getScreenWidth() - leftWidth - 20 - 20) / 3;
    rightItemWidth = ScreenAdaper.width(rightItemWidth);
    var rightItemHeigth = rightItemWidth + ScreenAdaper.height(32);

    return Row(
      children: <Widget>[
        _leftCateWidget(leftWidth),
        _rightCateWidget(rightItemWidth, rightItemHeigth)
      ],
    );
  }
}