package org.rain.spring.dao.impl;

import org.rain.spring.dao.BookDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

/**
 * @author liaojy
 * @date 2023/8/27 - 0:45
 */
@Repository
public class BookDaoImpl implements BookDao {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    public Integer getPriceByBookId(Integer bookId) {
        String sql = "select price from t_book where book_id = ?";
        Integer price = jdbcTemplate.queryForObject(sql, Integer.class,bookId);
        return price;
    }

    public void updateStockOfBook(Integer bookId) {
        String sql = "update t_book set stock = stock -1 where book_id = ?";
        jdbcTemplate.update(sql, bookId);
    }

    public void updateBalanceOfUser(Integer userId, Integer price) {
        String sql = "update t_user set balance = balance - ? where user_id = ?";
        jdbcTemplate.update(sql,price,userId);
    }
}

14.3.2、创建业务层接口BookService及其实现类

package org.rain.spring.service;

/**
 * @author liaojy
 * @date 2023/8/27 - 0:59
 */
public interface BookService {

    void buyBook(Integer bookId,Integer userId);

}

package org.rain.spring.service.impl;

import org.rain.spring.dao.BookDao;
import org.rain.spring.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @author liaojy
 * @date 2023/8/27 - 1:02
 */
@Service
public class BookServiceImpl implements BookService {

    @Autowired
    private BookDao bookDao;

    public void buyBook(Integer bookId, Integer userId) {

        //查询图书的价格
        Integer price = bookDao.getPriceByBookId(bookId);

        //更新图书的库存
        bookDao.updateStockOfBook(bookId);

        //更新用户的余额
        bookDao.updateBalanceOfUser(userId,price);

    }

}

14.3.3、创建控制层BookController

注意：因为控制层没用到接口，所以方法的访问修饰符要手动设置

package org.rain.spring.controller;

import org.rain.spring.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

/**
 * @author liaojy
 * @date 2023/8/27 - 1:07
 */
@Controller
public class BookController {

    @Autowired
    private BookService bookService;

    public void buyBook(Integer bookId, Integer userId){
        bookService.buyBook(bookId,userId);
    }

}

14.3.4、配置对注解组件的扫描

    <!--扫描注解组件-->
    <context:component-scan base-package="org.rain.spring"></context:component-scan>

14.3.5、创建测试类

模拟场景：

• 用户购买图书，先查询图书的价格，再更新图书的库存和用户的余额

• 假设id为1的用户（余额为50），购买id为1的图书（价格为80）

• 购买图书之后，用户的余额应为-30；但由于数据库中余额字段设置了无符号，因此无法将-30插入到余额字段；
  此时执行更新用户余额的sql语句会抛出异常