class CartInfoModel {

  String goodsId;

  String goodsName;

  int count;

  double price;

  String images;

  bool isCheck;

  CartInfoModel(

      {this.goodsId, this.goodsName, this.count, this.price, this.images, this.isCheck});

  CartInfoModel.fromJson(Map<String, dynamic> json) {

    goodsId = json['goodsId'];

    goodsName = json['goodsName'];

    count = json['count'];

    price = json['price'];

    images = json['images'];

    isCheck = json['isCheck'];

  }

  Map<String, dynamic> toJson() {

    final Map<String, dynamic> data = new Map<String, dynamic>();

    data['goodsId'] = this.goodsId;

    data['goodsName'] = this.goodsName;

    data['count'] = this.count;

    data['price'] = this.price;

    data['images'] = this.images;

    data['isCheck'] = this.isCheck;

    return data;

  }

}

import 'package:flutter/material.dart';

import 'package:shared_preferences/shared_preferences.dart';

import 'dart:convert';

import '../model/cartInfo.dart';

class CartProvide with ChangeNotifier{

  String cartString="[]";//声明一个变量 做持久化的存储

  List<CartInfoModel> cartList=[];

  //声明一个异步的方法,购物车操作放在前台不在请求后台的数据

  save(goodsId,goodsName,count,price,images) async {

    SharedPreferences prefs = await SharedPreferences.getInstance();

    cartString= prefs.getString('cartInfo');//先从持久化中获取

    var temp = cartString==null?[]:json.decode(cartString.toString());

    //声明list 强制类型是Map

    List<Map> tempList=(temp as List).cast();//把temp转成list

    bool isHave=false;//是否已经存在了这条记录

    int ival=;//foreach循环的索引

    //循环判断列表是否存在该goodsId的商品，如果有就数量+1

    tempList.forEach((item){

      if(item['goodsId']==goodsId){

        tempList[ival]['count']=item['count']+;

        cartList[ival].count++;

        isHave=true;

      }

      ival++;

    });

    //没有不存在这个商品，就把商品的json数据加入的tempList中

    if(!isHave){

      Map<String,dynamic> newGoods={

        'goodsId':goodsId,//传入进来的值

        'goodsName':goodsName,

        'count':count,

        'price':price,

        'images':images,

        'isCheck':true

      };

      tempList.add(newGoods);

      cartList.add(CartInfoModel.fromJson(newGoods));

    }

    cartString=json.encode(tempList).toString();//json数据转字符串

    // print('字符串》》》》》》》》》》》${cartString}');

    // print('字符串》》》》》》》》》》》${cartList}');

    prefs.setString('cartInfo', cartString);

    notifyListeners();

  }

  remove() async{

    SharedPreferences prefs=await SharedPreferences.getInstance();

    prefs.remove('cartInfo');

    cartList=[];

    print('清空完成----------------------');

    notifyListeners();

  }

  getCartInfo() async{

    SharedPreferences prefs=await SharedPreferences.getInstance();

    cartString=prefs.getString('cartInfo');//持久化中获得字符串

    print('购物车持久化的数据================>'+cartString);

    cartList=[];//把最终的结果先设置为空list

    if(cartString==null){

      cartList=[];//如果持久化内没有数据 那么就还是空的list

    }else{

      //声明临时的变量

      List<Map> tempList=(json.decode(cartString.toString()) as List).cast();

      tempList.forEach((item){

        cartList.add(CartInfoModel.fromJson(item));//json转成对象，加入到cartList中

      });

    }

    notifyListeners();//通知

  }

}

import 'package:flutter/material.dart';

import 'package:flutter_screenutil/flutter_screenutil.dart';

import '../../model/cartInfo.dart';

import './cart_count.dart';

class CartItem extends StatelessWidget {

  final CartInfoModel item;

  CartItem(this.item);

  @override

  Widget build(BuildContext context) {

   //print(item);

    return Container(

      margin: EdgeInsets.fromLTRB(5.0, 2.0, 5.0, 2.0),

      padding: EdgeInsets.fromLTRB(5.0, 10.0, 5.0, 10.0),

      decoration: BoxDecoration(

        color: Colors.white,

        border: Border(

          bottom: BorderSide(width: ,color: Colors.black12)

        )

      ),

      child: Row(

        children: <Widget>[

          _cartCheckBt(context,item),

          _cartImage(),

          _cartGoodsName(),

          _cartPrice()

        ],

      ),

    );

  }

  //复选框

  Widget _cartCheckBt(context,item){

    return Container(

      child: Checkbox(

        value: item.isCheck,//这里的值变成动态的

        activeColor: Colors.pink,//激活颜色设置为粉色

        onChanged:(bool val){

        }

      ),

    );

  }

  //商品图片

  Widget _cartImage(){

    return Container(

      width: ScreenUtil().setWidth(),

      padding: EdgeInsets.all(3.0),//内边距

      decoration: BoxDecoration(

        border: Border.all(width:1.0,color: Colors.black12)

      ),

      child: Image.network(item.images),//item声明好了 所以不用传递

    );

  }

  //商品名称

  Widget _cartGoodsName() {

    return Container(

      width: ScreenUtil().setWidth(),

      padding: EdgeInsets.all(),

      alignment: Alignment.topLeft,//顶端左对齐

      child: Column(

        children: <Widget>[

          Text(item.goodsName),

          CartCount()

        ],

      ),

    );

  }

  //商品价格

  Widget _cartPrice() {

    return Container(

      width: ScreenUtil().setWidth(),//只要合起来不超过750 就不会溢出

      alignment: Alignment.centerRight,//居中靠右

      child: Column(

        children: <Widget>[

          Text('￥${item.price}'),

          Container(//用来放icon删除按钮

            child: InkWell(

              onTap: (){},

              child: Icon(

                Icons.delete_forever,

                color: Colors.black26,//浅灰色

                size: ,

              ),

            ),

          )

        ],

      ),

    );

  }

}