13 Flutter仿京东商城项目 商品列表筛选以及上拉分页加载更多

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;
  // 一级导航数据
  /*
  价格升序：sort=price_1
  价格降序：sort=price_-1
  销量升序：sort=salecount_1
  销量降序：sort=salecount_-1
   */
  List _subHeaderList = [
    {"id": 1, "title": "综合", "fileds": 'all', "sort": -1},
    {"id": 2, "title": "销量", "fileds": 'salecount', "sort": -1},
    {"id": 3, "title": "价格", "fileds": 'price', "sort": -1},
    {"id": 4, "title": "筛选"},
  ];
  int _selectHeaderId = 1;

  //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(
                      width: 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();
    }
  }

  //导航改变的时候触发：
  _subHeaderChange(id) {
    if (id == 4) {
      _scaffoldKey.currentState.openEndDrawer();
    }
    setState(() {
      this._selectHeaderId = id;
      this._sort =
          "${this._subHeaderList[id - 1]['fileds']}_${this._subHeaderList[id - 1]['sort']}";

      //重置分页：
      this._page = 1;
      //重置数据：
      this._productList = [];

      this._subHeaderList[id - 1]['sort'] =
          this._subHeaderList[id - 1]['sort'] * -1;

      //回到顶部：
      _scrollController.jumpTo(0);

      //重置_hasMore
      this._hasMore = true;

      //重新请求数据：
      this._getProductListData();
    });
  }

  //显示Header icon
  Widget _showIcon(id) {
    if (id == 2 || id == 3) {
      if (this._subHeaderList[id - 1]['sort'] ==1) {
        return Icon(Icons.arrow_drop_down);
      }
      return Icon(Icons.arrow_drop_up);
    }
    return Text('');
  }

  //筛选导航：
  Widget _subHeaderWidget() {
    return Positioned(
      top: 0,
      height: ScreenAdaper.height(80),
      width: ScreenAdaper.width(750),
      child: Container(
        height: ScreenAdaper.height(80),
        width: ScreenAdaper.width(750),
        // color: Colors.red,
        decoration: BoxDecoration(
            border: Border(
                bottom: BorderSide(
                    width: 1, color: Color.fromRGBO(233, 233, 233, 0.9)))),
        child: Row(
            children: this._subHeaderList.map((value) {
          return Expanded(
            flex: 1,
            child: InkWell(
              child: Padding(
                padding: EdgeInsets.fromLTRB(
                    0, ScreenAdaper.height(20), 0, ScreenAdaper.height(20)),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    Text(
                      "${value['title']}",
                      textAlign: TextAlign.center,
                      style: TextStyle(
                          color: (this._selectHeaderId == value["id"])
                              ? Colors.red
                              : Colors.black),
                    ),
                    _showIcon(value['id'])
                  ],
                ),
              ),
              onTap: () {
                _subHeaderChange(value["id"]);
              },
            ),
          );
        }).toList()),
      ),
    );
  }

  @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()],
      ),
    );
  }
}