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)

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    }}