Android购物车项目快速开发

购物车项目，业务需要实现了一个购物车的项目，简单的了解下实现逻辑：数据计算等是在Adapter中计算出来的，通过在Adapter中计算出来的数据就可以回调到Activity中进行订单操作等功能业务逻辑，每一个店铺产生的数据是走一条流程的，（业务需求：不是作为一个类似淘宝，京东的平台数据又由平台分发，所以我们实现的是一对一的客户交易的交易流程)接着往下看：

1.界面使用到的控件

goodsAdapter = new GoodsCarAdapter(ShopCarAvtivity.this, result);
lv_refresh.setAdapter(goodsAdapter);
goodsAdapter.setCheckInterface(ShopCarAvtivity.this);// 关键步骤1,设置复选框接口
goodsAdapter.setModifyCountInterface(ShopCarAvtivity.this);// 关键步骤2,设置数量增减接口
for (int i = 0; i < goodsAdapter.getGroupCount(); i++) {
 lv_refresh.expandGroup(i);// 关键步骤3,初始化时，将ExpandableListView以展开的方式呈现
}

2.项目中使用到的数据接口

界面当中的复选框的接口回调

public interface CheckGoodsListener {
/**
 * 组选框状态改变触发的事件
 *
 * @param groupPosition 组元素位置
 * @param isChecked  组元素选中与否
 */
void checkGroup(int groupPosition, boolean isChecked);

/**
 * 子选框状态改变时触发的事件
 *
 * @param groupPosition 组元素位置
 * @param childPosition 子元素位置
 * @param isChecked  子元素选中与否
 */
void checkChild(int groupPosition, int childPosition, boolean isChecked);


/**
 * 购买
 * @param groupPosition
 * @param childPosition
 * @param isChecked
 */
void checkGoodsBuy(ShopCarModel shopCarModel, double totalMonery, int totalCount);

} 

商品增加和修改的接口

/**
 * 改变数量的接口
 * Created by zhuangAH on 2016-11-7.
 */

public interface ModifyCountListener {

 /**
  * 增加操作
  *
  * @param groupPosition 组元素位置
  * @param childPosition 子元素位置
  * @param showCountView 用于展示变化后数量的View
  * @param isChecked  子元素选中与否
  */
 void doIncrease(int groupPosition, int childPosition, View showCountView, boolean isChecked);

 /**
  * 删减操作
  *
  * @param groupPosition 组元素位置
  * @param childPosition 子元素位置
  * @param showCountView 用于展示变化后数量的View
  * @param isChecked  子元素选中与否
  */
 void doDecrease(int groupPosition, int childPosition, View showCountView, boolean isChecked);

 /**
  * 删除子item
  *
  * @param groupPosition
  * @param childPosition
  */
 void childDelete(int groupPosition, int childPosition);

}

3.在Adapter中计算商品的金额数量

单个店铺中有多个商品，所以这个店铺的布局，包含选择全组的按钮，使用了接口的回调 checkInterface.checkGroup(groupPosition, ((CheckBox) v).isChecked());来判断是否选中全组，在Activity中进行数据的便利是否选中商品之后再刷新数据。

 @Override
 public View getGroupView(final int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

  GroupViewHolder gholder = null;
  if (convertView != null && !(convertView.getTag() instanceof GroupViewHolder)) {
   convertView = null;
  }
  if (convertView == null) {
   gholder = new GroupViewHolder();
   convertView = View.inflate(context, R.layout.item_shopcart_group, null);
   gholder.determineChekbox = (CheckBox) convertView.findViewById(R.id.determine_chekbox);
   gholder.tvSourceName = (TextView) convertView.findViewById(R.id.tv_source_name);
   convertView.setTag(gholder);
  } else {
   gholder = (GroupViewHolder) convertView.getTag();
  }

  final ShopCarModel group = (ShopCarModel) getGroup(groupPosition);
  gholder.tvSourceName.setText(group.getFactoryName());
  gholder.determineChekbox.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    group.setChoosed(((CheckBox) v).isChecked());
    checkInterface.checkGroup(groupPosition, ((CheckBox) v).isChecked());
   }
  });
  gholder.determineChekbox.setChecked(group.isChoosed());
  return convertView;
 }

在Activity中计算便利数据

 /***
  * 校对组元素
  *
  * @param groupPosition 组元素位置
  * @param isChecked  组元素选中与否
  */
 @Override
 public void checkGroup(int groupPosition, boolean isChecked) {

  List<GoodsModel> goodsModelList = shopCarModelList.get(groupPosition).getGoodsModel();
  for (int i = 0; i < goodsModelList.size(); i++) {
   goodsModelList.get(i).setChoosed(isChecked);
  }
  goodsAdapter.notifyDataSetChanged();
 }

在商品中计算数据结果：

@Override
public View getChildView(final int groupPosition, final int childPosition, final boolean isLastChild, View convertView, final ViewGroup parent) {
 GoodsViewHolder goodsViewHolder = null;
 int totalCount = 0;
 double totalPrice = 0.00;

 if (convertView != null && !(convertView.getTag() instanceof GoodsViewHolder)) {
  convertView = null;
 }
 if (convertView == null) {
  goodsViewHolder = new GoodsViewHolder();
  convertView = View.inflate(context, R.layout.item_shopcart_product, null);
  goodsViewHolder.checkBox = (CheckBox) convertView.findViewById(R.id.check_box);
  goodsViewHolder.ivAdapterListPic = (ImageView) convertView.findViewById(R.id.iv_adapter_list_pic);
  goodsViewHolder.tvIntro = (TextView) convertView.findViewById(R.id.tv_intro);
  goodsViewHolder.tvPrice = (TextView) convertView.findViewById(R.id.tv_price);
  goodsViewHolder.tvBuyNum = (TextView) convertView.findViewById(R.id.tv_buy_num);
  goodsViewHolder.rlNoEdtor = (RelativeLayout) convertView.findViewById(R.id.rl_no_edtor);
  goodsViewHolder.tvReduce = (TextView) convertView.findViewById(R.id.tv_reduce);
  goodsViewHolder.tvNum = (TextView) convertView.findViewById(R.id.tv_num);
  goodsViewHolder.tvAdd = (TextView) convertView.findViewById(R.id.tv_add);
  goodsViewHolder.llChangeNum = (LinearLayout) convertView.findViewById(R.id.ll_change_num);
  goodsViewHolder.layout_item_foot = (LinearLayout) convertView.findViewById(R.id.layout_item_foot);
  goodsViewHolder.tv_goods_number = (TextView) convertView.findViewById(R.id.tv_goods_number);
  goodsViewHolder.tv_goods_menoy = (TextView) convertView.findViewById(R.id.tv_goods_menoy);
  goodsViewHolder.tv_buys = (TextView) convertView.findViewById(R.id.tv_buys);
  goodsViewHolder.laytou_car = (LinearLayout) convertView.findViewById(R.id.laytou_car);
  convertView.setTag(goodsViewHolder);
 } else {
  goodsViewHolder = (GoodsViewHolder) convertView.getTag();
 }
 //进行数据操作
 final GoodsModel goodsInfo = (GoodsModel) getChild(groupPosition, childPosition);
 if (goodsInfo != null) {
  //数量初始化为0,金额初始化为0
  goodsViewHolder.tv_goods_number.setText(TypeUtils.toString(0));
  goodsViewHolder.tv_goods_menoy.setText("￥ " + NumberUtils.formatMoneyScale(0.00));

  List<GoodsModel> goodsModel = CarUtrils.getGoodsList(goodShop, groupPosition);
  //判断是否最后一个
  if ((goodsModel.size() - 1) == childPosition) {
   goodsViewHolder.layout_item_foot.setVisibility(View.VISIBLE);
   /**
    * 统计操作<br>
    * 1.先清空全局计数器<br>
    * 2.遍历所有子元素，只要是被选中状态的，就进行相关的计算操作<br>
    * 3.给底部的textView进行数据填充
    */
   //1判断商品是否选中,再进行计算
   for (int j = 0; j < goodsModel.size(); j++) {
    GoodsModel model = goodsModel.get(j);
    if (model.isChoosed()) {
     totalCount += model.getSelectQty();
     totalPrice += TypeUtils.toDouble(NumberUtils.multiply(TypeUtils.toBigDecimal(NumberUtils.formatRounded(model.getPrice())), NumberUtils.toBigDecimal(model.getSelectQty())));
    }
   }

   if (totalPrice != 0.00) {
    goodsViewHolder.tv_goods_number.setText(TypeUtils.toString(totalCount));
    goodsViewHolder.tv_goods_menoy.setText(NumberUtils.formatRounded(TypeUtils.toBigDecimal(totalPrice)));
    goodsViewHolder.tv_buys.setBackgroundColor(context.getResources().getColor(R.color.main_color));
    goodsViewHolder.tv_buys.setEnabled(true);
   } else {
    goodsViewHolder.tv_goods_number.setText(TypeUtils.toString(0));
    goodsViewHolder.tv_goods_menoy.setText("￥ " + NumberUtils.formatMoneyScale(0.00));
    goodsViewHolder.tv_buys.setBackgroundColor(context.getResources().getColor(R.color.resport_line));
    goodsViewHolder.tv_buys.setEnabled(false);
   }

  } else {
   goodsViewHolder.layout_item_foot.setVisibility(View.GONE);
  }
  //设置基础数据
  if (goodsInfo.getImageSrc() != null) {
   Glide.with(context)
     .load(goodsInfo.getImageSrc())
     .centerCrop()
     .placeholder(R.miphtml" target="_blank">map.test2)
     .crossFade()
     .into(goodsViewHolder.ivAdapterListPic);
  }

  goodsViewHolder.tvIntro.setText(goodsInfo.getName());
  goodsViewHolder.tvPrice.setText("￥ " + NumberUtils.formatRounded(goodsInfo.getPrice()));
  goodsViewHolder.tvBuyNum.setText("X " + NumberUtils.formatQty(goodsInfo.getQty()));
  //set Goods Check
  goodsViewHolder.checkBox.setChecked(goodsInfo.isChoosed());
  goodsViewHolder.tvNum.setText(TypeUtils.toString(goodsInfo.getSelectQty()));

  //选中的状态下才能触发点击事件
  goodsViewHolder.tvAdd.setEnabled(true);
  goodsViewHolder.tvReduce.setEnabled(true);
  //加减
  final GoodsViewHolder finalGoodsViewHolder = goodsViewHolder;
  goodsViewHolder.tvAdd.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    modifyCountInterface.doIncrease(groupPosition, childPosition, finalGoodsViewHolder.tvNum, finalGoodsViewHolder.checkBox.isChecked());// 暴露增加接口

   }
  });
  final GoodsViewHolder finalGoodsViewHolder1 = goodsViewHolder;
  goodsViewHolder.tvReduce.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    modifyCountInterface.doDecrease(groupPosition, childPosition, finalGoodsViewHolder1.tvNum, finalGoodsViewHolder1.checkBox.isChecked());// 暴露删减接口
   }
  });

  //goods check state OnClick
  goodsViewHolder.checkBox.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    goodsInfo.setChoosed(((CheckBox) v).isChecked());
    ((CheckBox) v).setChecked(((CheckBox) v).isChecked());
    checkInterface.checkChild(groupPosition, childPosition, ((CheckBox) v).isChecked());
   }
  });
  //onClick to OrderDetailActivity
  final double finalTotalPrice = totalPrice;
  final int finalTotalCount = totalCount;
  goodsViewHolder.tv_buys.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    //check goods is not null
    //if not null can go other activity
    ShopCarModel shopCar = CarUtrils.getCheckShopCar(goodShop, groupPosition);
    if (shopCar != null && shopCar.getGoodsModel().size() > 0) {
     checkInterface.checkGoodsBuy(shopCar, finalTotalPrice, finalTotalCount);
    }
   }
  });
 }

 goodsViewHolder.laytou_car.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
   UIHelper.toShopCarGoodsDetailActivity(context, goodsInfo);
  }
 });
 return convertView;
}

以上代码的是先判断当前组是否为一个店铺中的最后一个，在最后一个元素中局部计算当前的Group的数据，根据数据来选择是否复位数据展示以及显示，把计算的数据展示出来，最后通过接口回调的方式跳转界面，把数据传到Activity中去。就这样子就处理完这个购物车的逻辑，以上可能不符合你的逻辑，但是你可以稍微修改就拿来使用。

Github地址: https://github.com/anhuifix/singleShopCar/tree/master

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