<!-- 引入外部属性文件 -->
            <context:property-placeholder location="classpath:jdbc.properties"/>
            <!-- 配置数据源 -->
            <bean id="comboPooledDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
                <property name="user" value="${jdbc.user}"></property>
                <property name="password" value="${jdbc.passowrd}"></property>
                <property name="jdbcUrl" value="${jdbc.url}"></property>
                <property name="driverClass" value="${jdbc.driver}"></property>
            </bean>

<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
                <property name="dataSource" ref="comboPooledDataSource"></property>
            </bean>

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

@Repository
            public class BookDao {
                @Autowired
                private JdbcTemplate  jdbcTemplate;
                /**
                 *  [1]根据isbn的值查询书的价格
                    [2]根据isbn的值减少书的库存，假设每次都只买1本书
                    [3]根据用户名减少用户账户中的余额，减少的额度就是书的价格
                 */
                
                public int findPriceByIsbn(String isbn){
                    String sql = "SELECT price FROM book WHERE isbn = ?";
                    Integer price = jdbcTemplate.queryForObject(sql, Integer.class, isbn);
                    return price;
                }

            }

//[2]根据isbn的值减少书的库存，假设每次都只买1本书
public void updateStockByIsbn(String isbn){
                    String sql = "UPDATE book_stock SET stock = stock -1 WHERE isbn = ?";
                    jdbcTemplate.update(sql, isbn);
                }
          继续测试:
              public class TestDataSource {
                    private ApplicationContext ioc = new ClassPathXmlApplicationContext("applicationContext.xml");
                    private BookDao bean = ioc.getBean(BookDao.class);
                    
                    @Test
                    public void test02() throws SQLException {        
                        bean.updateStockByIsbn("ISBN-004");
                    }
              }

public void updateBalance(String userName,int price){
                    String sql = "UPDATE account SET balance = balance - ? WHERE username = ?";
                    jdbcTemplate.update(sql, price,userName);
                }

@Service
            public class BookService {
                @Autowired
                private BookDao bookDao;
                
                public void doCash(String isbn,String username){
                    int price = bookDao.findPriceByIsbn(isbn);
                    bookDao.updateStockByIsbn(isbn);
                    bookDao.updateBalance(username, price);
                }
            }

public class TestDataSource {
                private ApplicationContext ioc = new ClassPathXmlApplicationContext("applicationContext.xml");
                private BookDao bean = ioc.getBean(BookDao.class);
                private BookService bookService  = ioc.getBean(BookService.class);
                
                @Test
                public void test04() throws SQLException {        
                    bookService.doCash("ISBN-001","Tom");
                }
           }

              <!-- 配置事务管理器,并为事务管理器配置数据源！-->
            <bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
                <property name="dataSource" ref="comboPooledDataSource"></property>
            </bean>
            <!-- 开启基于注解的声明式事务功能,需要设置transaction-manager属性-->
            <!-- 如果 事务管理器的id正好是transaction-manager的默认值transactionManager,则可以省略-->
            <tx:annotation-driven transaction-manager="dataSourceTransactionManager"/>
　　　　　　　　<!--然后在service层的doCash方法上加上：@Transactional注解这样就开启了事务！需要注意的是事务一般是加在service层的！-->