Spring学习-day13

Posted 2020-10-27

需求：

用户购买图书，购买成功，库存更新，账户余额更新，若余额或者库存不够，均不能购买成功，产生异常

数据表:

account: 账户表(包括用户名和余额)
book：图书表(id, 书名, 图书价格)
book_stock：库存表(id, 图书库存)

代码实现:

1. 图书购买时的接口

package com.atguigu.spring.tx;

public interface BookShopDao {

    //根据书号获取书的单价
    public int findBookPriceByIsbn(String isbn);

    //更新书的库存, 使书号对应的库存 - 1
    public void updateBookStock(String isbn);

    //更新用户的账户余额: 使 username 的 balance - price
    public void updateUserAccount(String username, int price);
}

package com.atguigu.spring.tx;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

@Repository("bookShopDao")
public class BookShopDaoImpl implements BookShopDao {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public int findBookPriceByIsbn(String isbn) {
        String sql = "select price from book where isbn = ?";
        return jdbcTemplate.queryForObject(sql, Integer.class, isbn);
    }

    @Override
    public void updateBookStock(String isbn) {
        //检查书的库存是否足够, 若不够, 则抛出异常
        String sql2 = "select stock from book_stock where isbn = ?";
        int stock = jdbcTemplate.queryForObject(sql2, Integer.class, isbn);
        if (stock == 0) {
            throw new BookStockException("库存不足！");
        }

        String sql = "update book_stock set stock = stock -1 where isbn = ?";
        jdbcTemplate.update(sql, isbn);
    }

    @Override
    public void updateUserAccount(String username, int price) {
        //验证余额是否足够, 若不足, 则抛出异常
        String sql2 = "select balance from account where username = ?";
        int balance = jdbcTemplate.queryForObject(sql2, Integer.class, username);
        if(balance < price){
            throw new UserAccountException("余额不足!");
        }

        String sql = "update account set balance = balance - ? where username = ?";
        jdbcTemplate.update(sql, price, username);
    }

}

package com.atguigu.spring.tx;

public interface BookShopService {
    public void purchase(String username, String isbn);
}

package com.atguigu.spring.tx;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service("bookShopService")
public class BookShopServiceImpl implements BookShopService {

    @Autowired
    private BookShopDao bookShopDao;

    //添加事务注解
    @Transactional
    @Override
    public void purchase(String username, String isbn) {
        //1. 获取书的单价
        int price = bookShopDao.findBookPriceByIsbn(isbn);

        //2. 更新书的库存
        bookShopDao.updateBookStock(isbn);

        //3. 更新用户余额
        bookShopDao.updateUserAccount(username, price);
    }

}

2. 测试方法

package com.atguigu.spring.tx;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringTransactionTest {

    private ApplicationContext ctx = null;
    private BookShopDao bookShopDao = null;
    private BookShopService bookShopService = null;

    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        bookShopDao = ctx.getBean(BookShopDao.class);
        bookShopService  = ctx.getBean(BookShopService.class);
    }

    @Test
    public void testBookShopService() {
        bookShopService.purchase("AA", "1001");
    }

    @Test
    public void testBookShopDaoUpdateUserAccount(){
        bookShopDao.updateUserAccount("AA", 100);
    }

    @Test
    public void testBookShopDaoUpdateBookStock(){
        bookShopDao.updateBookStock("1001");
    }

    @Test
    public void testBookShopDaoFindPriceByIsbn() {
        System.out.println(bookShopDao.findBookPriceByIsbn("1001"));
    }
}

3. 错误则抛出异常

package com.atguigu.spring.tx;

public class BookStockException extends RuntimeException{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public BookStockException() {
        super();
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message, Throwable cause) {
        super(message, cause);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message) {
        super(message);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(Throwable cause) {
        super(cause);
        // TODO Auto-generated constructor stub
    }

}

package com.atguigu.spring.tx;

public class UserAccountException extends RuntimeException{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public UserAccountException() {
        super();
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String message, Throwable cause, boolean enableSuppression,
            boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String message, Throwable cause) {
        super(message, cause);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String message) {
        super(message);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(Throwable cause) {
        super(cause);
        // TODO Auto-generated constructor stub
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <context:component-scan base-package="com.atguigu.spring"></context:component-scan>

    <!-- 导入资源文件 -->
    <context:property-placeholder location="classpath:db.properties"/>

    <!-- 配置 C3P0 数据库 -->
    <bean id="dataSource"
        class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="${jdbc.user}"></property>
        <property name="password" value="${jdbc.password}"></property>
        <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
        <property name="driverClass" value="${jdbc.driverClass}"></property>

        <property name="initialPoolSize" value="${jdbc.initPoolSize}"></property>
        <property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property>
    </bean>

    <!-- 配置 Spring 的 JdbcTemplate -->
    <bean id="jdbcTemplate" 
        class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <!-- 配置事务管理器 -->
    <bean id="transactionManager" 
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <!-- 启用事务 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>

</beans>