4.15博客
可恶啊，原以为高中数学学过概率的东西概率论应该好学
竟然也难起来了
学习内容：只有安卓
package com.dongnaoedu.chapter06;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import com.dongnaoedu.chapter06.database.ShoppingDBHelper;
import com.dongnaoedu.chapter06.enity.CartInfo;
import com.dongnaoedu.chapter06.enity.GoodsInfo;
import com.dongnaoedu.chapter06.util.ToastUtil;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ShoppingCartActivity extends AppCompatActivity implements View.OnClickListener {
private TextView tv_count;
private LinearLayout ll_cart;
private ShoppingDBHelper mDBHelper;
// 声明一个购物车中的商品信息列表
private List<CartInfo> mCartList;
// 声明一个根据商品编号查找商品信息的映射，把商品信息缓存起来，这样不用每一次都去查询数据库
private Map<Integer, GoodsInfo> mGoodsMap = new HashMap<>();
private TextView tv_total_price;
private LinearLayout ll_empty;
private LinearLayout ll_content;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_shopping_cart);
TextView tv_title = findViewById(R.id.tv_title);
tv_title.setText("购物车");
ll_cart = findViewById(R.id.ll_cart);
tv_total_price = findViewById(R.id.tv_total_price);
tv_count = findViewById(R.id.tv_count);
tv_count.setText(String.valueOf(MyApplication.getInstance().goodsCount));
mDBHelper = ShoppingDBHelper.getInstance(this);
findViewById(R.id.iv_back).setOnClickListener(this);
findViewById(R.id.btn_shopping_channel).setOnClickListener(this);
findViewById(R.id.btn_clear).setOnClickListener(this);
findViewById(R.id.btn_settle).setOnClickListener(this);
ll_empty = findViewById(R.id.ll_empty);
ll_content = findViewById(R.id.ll_content);
}
@Override
protected void onResume() {
super.onResume();
showCart();
}
// 展示购物车中的商品列表
private void showCart() {
// 移除下面的所有子视图
ll_cart.removeAllViews();
// 查询购物车数据库中所有的商品记录
mCartList = mDBHelper.queryAllCartInfo();
if (mCartList.size() == 0) {
return;
}
for (CartInfo info : mCartList) {
// 根据商品编号查询商品数据库中的商品记录
GoodsInfo goods = mDBHelper.queryGoodsInfoById(info.goodsId);
mGoodsMap.put(info.goodsId, goods);
// 获取布局文件item_cart.xml的根视图
View view = LayoutInflater.from(this).inflate(R.layout.item_cart, null);
ImageView iv_thumb = view.findViewById(R.id.iv_thumb);
TextView tv_name = view.findViewById(R.id.tv_name);
TextView tv_desc = view.findViewById(R.id.tv_desc);
TextView tv_count = view.findViewById(R.id.tv_count);
TextView tv_price = view.findViewById(R.id.tv_price);
TextView tv_sum = view.findViewById(R.id.tv_sum);
iv_thumb.setImageURI(Uri.parse(goods.picPath));
tv_name.setText(goods.name);
tv_desc.setText(goods.description);
tv_count.setText(String.valueOf(info.count));
tv_price.setText(String.valueOf((int) goods.price));
// 设置商品总价
tv_sum.setText(String.valueOf((int) (info.count * goods.price)));
// 给商品行添加长按事件。长按商品行就删除该商品
view.setOnLongClickListener(v -> {
AlertDialog.Builder builder = new AlertDialog.Builder(ShoppingCartActivity.this);
builder.setMessage("是否从购物车删除" + goods.name + "？");
builder.setPositiveButton("是", (dialog, which) -> {
// 移除当前视图
ll_cart.removeView(v);
// 删除该商品
deleteGoods(info);
});
builder.setNegativeButton("否", null);
builder.create().show();
return true;
});
// 给商品行添加点击事件。点击商品行跳到商品的详情页
view.setOnClickListener(v -> {
Intent intent = new Intent(ShoppingCartActivity.this, ShoppingDetailActivity.class);
intent.putExtra("goods_id", goods.id);
startActivity(intent);
});
// 往购物车列表添加该商品行
ll_cart.addView(view);
}
// 重新计算购物车中的商品总金额
refreshTotalPrice();
}
private void deleteGoods(CartInfo info) {
MyApplication.getInstance().goodsCount -= info.count;
// 从购物车的数据库中删除商品
mDBHelper.deleteCartInfoByGoodsId(info.goodsId);
// 从购物车的列表中删除商品
CartInfo removed = null;
for (CartInfo cartInfo : mCartList) {
if (cartInfo.goodsId == info.goodsId) {
removed = cartInfo;
break;
}
}
mCartList.remove(removed);
// 显示最新的商品数量
showCount();
ToastUtil.show(this, "已从购物车删除" + mGoodsMap.get(info.goodsId).name);
mGoodsMap.remove(info.goodsId);
// 刷新购物车中所有商品的总金额
refreshTotalPrice();
}
// 显示购物车图标中的商品数量
private void showCount() {
tv_count.setText(String.valueOf(MyApplication.getInstance().goodsCount));
// 购物车中没有商品，显示“空空如也”
if (MyApplication.getInstance().goodsCount == 0) {
ll_empty.setVisibility(View.VISIBLE);
ll_content.setVisibility(View.GONE);
ll_cart.removeAllViews();
} else {
ll_content.setVisibility(View.VISIBLE);
ll_empty.setVisibility(View.GONE);
}
}
// 重新计算购物车中的商品总金额
private void refreshTotalPrice() {
int totalPrice = 0;
for (CartInfo info : mCartList) {
GoodsInfo goods = mGoodsMap.get(info.goodsId);
totalPrice += goods.price * info.count;
}
tv_total_price.setText(String.valueOf(totalPrice));
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.iv_back:
// 点击了返回图标
// 关闭当前页面
finish();
break;
case R.id.btn_shopping_channel:
// 从购物车页面跳到商场页面
Intent intent = new Intent(this, ShoppingChannelActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
break;
case R.id.btn_clear:
// 清空购物车数据库
mDBHelper.deleteAllCartInfo();
MyApplication.getInstance().goodsCount = 0;
// 显示最新的商品数量
showCount();
ToastUtil.show(this, "购物车已清空");
break;
case R.id.btn_settle:
// 点击了“结算”按钮
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("结算商品");
builder.setMessage("客官抱歉，支付功能尚未开通，请下次再来");
builder.setPositiveButton("我知道了", null);
builder.create().show();
break;
}
}
}
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