3.18
周一
概率论英语和毛概还有web
课很多但每日编程还是要有的
package com.dongnaoedu.chapter06.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import com.dongnaoedu.chapter06.enity.CartInfo;
import com.dongnaoedu.chapter06.enity.GoodsInfo;
import java.util.ArrayList;
import java.util.List;
public class ShoppingDBHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "shopping.db";
// 商品信息表
private static final String TABLE_GOODS_INFO = "goods_info";
// 购物车信息表
private static final String TABLE_CART_INFO = "cart_info";
private static final int DB_VERSION = 1;
private static ShoppingDBHelper mHelper = null;
private SQLiteDatabase mRDB = null;
private SQLiteDatabase mWDB = null;
private ShoppingDBHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
// 利用单例模式获取数据库帮助器的唯一实例
public static ShoppingDBHelper getInstance(Context context) {
if (mHelper == null) {
mHelper = new ShoppingDBHelper(context);
}
return mHelper;
}
// 打开数据库的读连接
public SQLiteDatabase openReadLink() {
if (mRDB == null || !mRDB.isOpen()) {
mRDB = mHelper.getReadableDatabase();
}
return mRDB;
}
// 打开数据库的写连接
public SQLiteDatabase openWriteLink() {
if (mWDB == null || !mWDB.isOpen()) {
mWDB = mHelper.getWritableDatabase();
}
return mWDB;
}
// 关闭数据库连接
public void closeLink() {
if (mRDB != null && mRDB.isOpen()) {
mRDB.close();
mRDB = null;
}
if (mWDB != null && mWDB.isOpen()) {
mWDB.close();
mWDB = null;
}
}
// 创建数据库，执行建表语句
@Override
public void onCreate(SQLiteDatabase db) {
// 创建商品信息表
String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_GOODS_INFO +
"(_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
" name VARCHAR NOT NULL," +
" description VARCHAR NOT NULL," +
" price FLOAT NOT NULL," +
" pic_path VARCHAR NOT NULL);";
db.execSQL(sql);
// 创建购物车信息表
sql = "CREATE TABLE IF NOT EXISTS " + TABLE_CART_INFO +
"(_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
" goods_id INTEGER NOT NULL," +
" count INTEGER NOT NULL);";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
// 添加多条商品信息
public void insertGoodsInfos(List<GoodsInfo> list) {
// 插入多条记录，要么全部成功，要么全部失败
try {
mWDB.beginTransaction();
for (GoodsInfo info : list) {
ContentValues values = new ContentValues();
values.put("name", info.name);
values.put("description", info.description);
values.put("price", info.price);
values.put("pic_path", info.picPath);
mWDB.insert(TABLE_GOODS_INFO, null, values);
}
mWDB.setTransactionSuccessful();
} catch (Exception e) {
e.printStackTrace();
} finally {
mWDB.endTransaction();
}
}
// 查询所有的商品信息
public List<GoodsInfo> queryAllGoodsInfo() {
String sql = "select * from " + TABLE_GOODS_INFO;
List<GoodsInfo> list = new ArrayList<>();
Cursor cursor = mRDB.rawQuery(sql, null);
while (cursor.moveToNext()) {
GoodsInfo info = new GoodsInfo();
info.id = cursor.getInt(0);
info.name = cursor.getString(1);
info.description = cursor.getString(2);
info.price = cursor.getFloat(3);
info.picPath = cursor.getString(4);
list.add(info);
}
cursor.close();
return list;
}
// 添加商品到购物车
public void insertCartInfo(int goodsId) {
// 如果购物车中不存在该商品，添加一条信息
CartInfo cartInfo = queryCartInfoByGoodsId(goodsId);
ContentValues values = new ContentValues();
values.put("goods_id", goodsId);
if (cartInfo == null) {
values.put("count", 1);
mWDB.insert(TABLE_CART_INFO, null, values);
} else {
// 如果购物车中已经存在该商品，更新商品数量
values.put("_id", cartInfo.id);
values.put("count", ++cartInfo.count);
mWDB.update(TABLE_CART_INFO, values, "_id=?", new String[]{String.valueOf(cartInfo.id)});
}
}
// 根据商品信息ID查询购物车信息
private CartInfo queryCartInfoByGoodsId(int goodsId) {
Cursor cursor = mRDB.query(TABLE_CART_INFO, null, "goods_id=?", new String[]{String.valueOf(goodsId)}, null, null, null);
CartInfo info = null;
if (cursor.moveToNext()) {
info = new CartInfo();
info.id = cursor.getInt(0);
info.goodsId = cursor.getInt(1);
info.count = cursor.getInt(2);
}
return info;
}
// 统计购物车中商品的总数量
public int countCartInfo() {
int count = 0;
String sql = "select sum(count) from " + TABLE_CART_INFO;
Cursor cursor = mRDB.rawQuery(sql, null);
if (cursor.moveToNext()) {
count = cursor.getInt(0);
}
return count;
}
// 查询购物车中所有的信息列表
public List<CartInfo> queryAllCartInfo() {
List<CartInfo> list = new ArrayList<>();
Cursor cursor = mRDB.query(TABLE_CART_INFO, null, null, null, null, null, null);
while (cursor.moveToNext()) {
CartInfo info = new CartInfo();
info.id = cursor.getInt(0);
info.goodsId = cursor.getInt(1);
info.count = cursor.getInt(2);
list.add(info);
}
return list;
}
// 根据商品ID查询商品信息
public GoodsInfo queryGoodsInfoById(int goodsId) {
GoodsInfo info = null;
Cursor cursor = mRDB.query(TABLE_GOODS_INFO, null, "_id=?", new String[]{String.valueOf(goodsId)}, null, null, null);
if (cursor.moveToNext()) {
info = new GoodsInfo();
info.id = cursor.getInt(0);
info.name = cursor.getString(1);
info.description = cursor.getString(2);
info.price = cursor.getFloat(3);
info.picPath = cursor.getString(4);
}
return info;
}
// 根据商品ID删除购物车信息
public void deleteCartInfoByGoodsId(int goodsId) {
mWDB.delete(TABLE_CART_INFO, "goods_id=?", new String[]{String.valueOf(goodsId)});
}
// 删除所有购物车信息
public void deleteAllCartInfo() {
mWDB.delete(TABLE_CART_INFO, "1=1", null);
}
}
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