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.mipmap.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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