Spring 模拟转账开发实战小结

// 接口：声明转账方法
public interface AccountService {
    void pay(String out, String in, double money); // 付款人、收款人、金额
}

// 实现类：调用Dao完成转账
public class AccountServiceImpl implements AccountService {
    private AccountDao accountDao; // 注入Dao层对象

    public void setAccountDao(AccountDao accountDao) {
        this.accountDao = accountDao;
    }

    @Override
    public void pay(String out, String in, double money) {
        accountDao.outMoney(out, money); // 付款方扣款
        accountDao.inMoney(in, money); // 收款方加款
    }
}

// 接口：定义数据库操作
public interface AccountDao {
    void outMoney(String out, double money); // 扣款
    void inMoney(String in, double money); // 加款
}

// 实现类：使用JdbcTemplate操作数据库
public class AccountDaoImpl implements AccountDao {
    private JdbcTemplate jdbcTemplate; // 注入JdbcTemplate

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    @Override
    public void outMoney(String out, double money) {
        jdbcTemplate.update("update account set money=money-? where name=?", money, out);
    }

    @Override
    public void inMoney(String in, double money) {
        jdbcTemplate.update("update account set money=money+? where name=?", money, in);
    }
}

<beans ...>
    <!-- 加载数据库配置 -->
    <context:property-placeholder location="classpath:jdbc.properties"/>
    
    <!-- 配置Druid连接池 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    
    <!-- 配置JdbcTemplate -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    
    <!-- 配置Service和Dao，注入依赖 -->
    <bean id="accountService" class="com.qcbyjy.demo2.AccountServiceImpl">
        <property name="accountDao" ref="accountDao"/>
    </bean>
    
    <bean id="accountDao" class="com.qcbyjy.demo2.AccountDaoImpl">
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>
</beans>

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext_dao1.xml")
public class Demo2 {
    @Autowired
    private AccountService accountService;

    @Test
    public void testPay() {
        accountService.pay("熊大", "熊二", 100); // 模拟熊大给熊二转账100元
    }
}

public class AccountDaoImpl extends JdbcDaoSupport implements AccountDao {
    @Override
    public void outMoney(String out, double money) {
        // 通过getJdbcTemplate()获取模板对象
        this.getJdbcTemplate().update("update account set money=money-? where name=?", money, out);
    }

    @Override
    public void inMoney(String in, double money) {
        this.getJdbcTemplate().update("update account set money=money+? where name=?", money, in);
    }
}

<bean id="accountDao" class="com.qcbyjy.demo3.AccountDaoImpl">
    <property name="dataSource" ref="dataSource"/> <!-- 注入数据源 -->
</bean>

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

    <!-- 启用注解事务 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

@Service
public class AccountServiceImpl implements AccountService {
    @Autowired
    private AccountDao accountDao;

    // 声明该方法需要事务支持
    @Transactional
    @Override
    public void pay(String out, String in, double money) {
        accountDao.outMoney(out, money); // 若此处抛出异常，两个操作都会回滚
        accountDao.inMoney(in, money);
    }
}