Spring中的事务管理实例详解

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balcance-price
    public void updateUserAccount(String username, int price);
   
}

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) {
        //检查余额是否不足，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);
    }

}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

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

    @Autowired
    private BookShopDao bookShopDao;
   
    /**
     * 1.添加事务注解
     * 使用propagation 指定事务的传播行为，即当前的事务方法被另外一个事务方法调用时如何使用事务。
     * 默认取值为REQUIRED，即使用调用方法的事务
     * REQUIRES_NEW：使用自己的事务，调用的事务方法的事务被挂起。
     *
     * 2.使用isolation 指定事务的隔离级别，最常用的取值为READ_COMMITTED
     * 3.默认情况下 Spring 的声明式事务对所有的运行时异常进行回滚，也可以通过对应的属性进行设置。通常情况下，默认值即可。
     * 4.使用readOnly 指定事务是否为只读。 表示这个事务只读取数据但不更新数据，这样可以帮助数据库引擎优化事务。若真的是一个只读取数据库值得方法，应设置readOnly=true
     * 5.使用timeOut 指定强制回滚之前事务可以占用的时间。
     */
    @Transactional(propagation=Propagation.REQUIRES_NEW,
            isolation=Isolation.READ_COMMITTED,
            noRollbackFor={UserAccountException.class},
            readOnly=true, timeout=3)
    @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);;
    }
}

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

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

    public BookStockException(String arg0, Throwable arg1, boolean arg2,
            boolean arg3) {
        super(arg0, arg1, arg2, arg3);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String arg0, Throwable arg1) {
        super(arg0, arg1);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(Throwable arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }
}

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

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

    public UserAccountException(String arg0, Throwable arg1, boolean arg2,
            boolean arg3) {
        super(arg0, arg1, arg2, arg3);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String arg0, Throwable arg1) {
        super(arg0, arg1);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(Throwable arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }
}

import java.util.List;

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

@Service("cashier")
public class CashierImpl implements Cashier {
    @Autowired
    private BookShopService bookShopService;
   
    @Transactional
    @Override
    public void checkout(String username, List<String> isbns) {
        for(String isbn : isbns) {
            bookShopService.purchase(username, isbn);
        }
    }
}

import java.util.Arrays;

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

public class SpringTransitionTest {
   
    private ApplicationContext ctx = null;
    private BookShopDao bookShopDao = null;
    private BookShopService bookShopService = null;
    private Cashier cashier = null;
    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        bookShopDao = ctx.getBean(BookShopDao.class);
        bookShopService = ctx.getBean(BookShopService.class);
        cashier = ctx.getBean(Cashier.class);
    }
   
    @Test
    public void testBookShopDaoFindPriceByIsbn() {
        System.out.println(bookShopDao.findBookPriceByIsbn("1001"));
    }

    @Test
    public void testBookShopDaoUpdateBookStock(){
        bookShopDao.updateBookStock("1001");
    }
   
    @Test
    public void testBookShopDaoUpdateUserAccount(){
        bookShopDao.updateUserAccount("AA", 100);
    }
    @Test
    public void testBookShopService(){
        bookShopService.purchase("AA", "1001");
    }
   
    @Test
    public void testTransactionPropagation(){
        cashier.checkout("AA", Arrays.asList("1001", "1002"));
    }
}