Android实现一个简易版本的购物车小案例

package com.android.shoppingcart.adapter; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.ImageView; import android.widget.TextView; import android.widget.Toast; import com.android.shoppingcart.R; import com.android.shoppingcart.constants.BizConstants; import com.android.shoppingcart.db.InitDataBase; import com.android.shoppingcart.pojo.GoodsVo; import java.util.List; public class GoodsGridViewAdapter extends BaseAdapter { private List<GoodsVo> goodsVoList; private Context context; // 数据库对象 private InitDataBase sqlite; public GoodsGridViewAdapter(Context context, List<GoodsVo> goodsVoList) { this.context = context; this.goodsVoList = goodsVoList; } @Override public int getCount() { if (goodsVoList == null) { return 0; } return goodsVoList.size(); } @Override public Object getItem(int position) { return goodsVoList.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO 加载 GridView 组件中的每一项样式 convertView = LayoutInflater.from(context).inflate(R.layout.activity_goods_item, null); // 获取里面的组件 ImageView imageView = convertView.findViewById(R.id.goodsPicture); TextView nameTextView = convertView.findViewById(R.id.goodsName); TextView priceTextView = convertView.findViewById(R.id.price); GoodsVo goodsVo = goodsVoList.get(position); imageView.setImageResource(R.drawable.phone_big); nameTextView.setText(goodsVo.getName()); priceTextView.setText("￥" + goodsVo.getPrice()); Button goods_btn = convertView.findViewById(R.id.goods_btn); goods_btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // 保存数据到购物车 // 初始化数据库 sqlite = new InitDataBase(context, BizConstants.DATA_BASE, null, 1); SQLiteDatabase database = sqlite.getReadableDatabase(); // 先查询是否存在商品 String selection = "gid = ?"; String[] selectionArgs = new String[]{goodsVo.getGid()}; Cursor cursor = database.query(BizConstants.TABLE_SHOPPING_CART, null, selection, selectionArgs, null, null, null, null); int num = 0; boolean flag = true; String sid = ""; if (cursor != null && cursor.moveToFirst()) { int columnIndex = cursor.getColumnIndex("num"); String numStr = cursor.getString(columnIndex); num = Integer.parseInt(numStr) + 1; flag = false; int sidIndex = cursor.getColumnIndex("sid"); sid = cursor.getString(sidIndex); } else { num = 1; } ContentValues values = new ContentValues(); values.put("gid", goodsVo.getGid()); values.put("goods_name", goodsVo.getName()); values.put("price", goodsVo.getPrice()); values.put("num", num); if (flag) { database.insert(BizConstants.TABLE_SHOPPING_CART, null, values); } else { selection = "sid = ?"; selectionArgs = new String[]{sid}; database.update(BizConstants.TABLE_SHOPPING_CART, values, selection, selectionArgs); } Toast.makeText(context, "加入购物车成功", Toast.LENGTH_SHORT).show(); } }); return convertView; } }