day 24

购物车的实现

首先是在商品详情页点击加入购物车后，把该物品的数据存贮到一个集合中。

这里需要设计一个类实现数据的添加，删除和修改。

定义物品数据类

package Home.Data;

import java.io.Serializable;

public class Wares implements Serializable {


    private Long id;
    private String name;
    private String imgUrl;
    private String description;
    private int price;


    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getImgUrl() {
        return imgUrl;
    }

    public void setImgUrl(String imgUrl) {
        this.imgUrl = imgUrl;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }
}

定义购物车数据类继承物品数据 添加数量属性

package Home.Data;

import java.io.Serializable;


public class ShoppingCart extends Wares implements Serializable {


    private int count;
    private boolean isChecked=true;



    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public boolean isChecked() {
        return isChecked;
    }

    public void setIsChecked(boolean isChecked) {
        this.isChecked = isChecked;
    }





}

定义数据存储类包含一些添加删除的方法

package Home.utils;

import android.content.Context;
import android.util.SparseArray;

import com.google.gson.reflect.TypeToken;

import java.util.ArrayList;
import java.util.List;

import Home.Data.ShoppingCart;



public class CartProvider {



    public static final String CART_JSON="cart_json";

    private SparseArray<ShoppingCart> datas =null;


    private  Context mContext;


    public CartProvider(Context context){

        mContext = context;
       datas = new SparseArray<>(200);
        listToSparse();

    }



    public void put(ShoppingCart cart){



            ShoppingCart temp = datas.get(cart.getId().intValue());

            if (temp != null) {
                temp.setCount(temp.getCount() + 1);
            } else {
                temp = cart;
                temp.setCount(1);
            }

            datas.put(cart.getId().intValue(), temp);


        commit();

    }

    public void update(ShoppingCart cart){

        datas.put(cart.getId().intValue(),cart);
        commit();
    }

    public void delete(ShoppingCart cart){
        datas.delete(cart.getId().intValue());
        commit();
    }

    public List<ShoppingCart> getAll(){

        return  getDataFromLocal();
    }


    public void commit(){


        List<ShoppingCart> carts = sparseToList();

        PreferencesUtils.putString(mContext,CART_JSON,JSONUtil.toJSON(carts));

    }


    private List<ShoppingCart> sparseToList(){


        int size = datas.size();

        List<ShoppingCart> list = new ArrayList<>(size);
        for (int i=0;i<size;i++){

            list.add(datas.valueAt(i));
        }
        return list;

    }



    private void listToSparse(){

        List<ShoppingCart> carts =  getDataFromLocal();

        if(carts!=null && carts.size()>0){

            for (ShoppingCart cart:
                    carts) {

                datas.put(cart.getId().intValue(),cart);
            }
        }

    }



    public  List<ShoppingCart> getDataFromLocal(){

        String json = PreferencesUtils.getString(mContext,CART_JSON);
        List<ShoppingCart> carts =null;
        if(json !=null ){

            carts = JSONUtil.fromJson(json,new TypeToken<List<ShoppingCart>>(){}.getType());

        }

        return  carts;

    }



}