Spring框架声明是事务

声明式事务（Declarative Transaction Management）是Spring框架提供的一种对程序事务进行管理的方式。这种管理方式的核心思想是采用声明的方式（通常是在配置文件中声明，而非在代码中硬编码）来处理事务，从而简化开发过程，降低开发者处理复杂事务的难度。
在声明式事务中，开发者通过注解（如@Transactional）或基于配置的XML来管理事务，而不需要依赖底层API进行硬编码。这使得业务逻辑对象无需意识到它们正处于事务管理之中，因为事务管理属于系统层面的服务，而不是业务逻辑的一部分。因此，当需要改变事务管理策略时，只需在配置文件中重新配置即可，无需修改代码并重新编译，从而大大提高了维护的便利性。

转账案例

• dao接口

package com.powernode.bank.dao;
 
 
import com.powernode.bank.pojo.Account;
 
public interface AccountDao {
    //根据账号查询账户信息
    Account selectByActno(String actno);
 
    //更新账户信息
    int update(Account act);
 
    //保存账户信息
    int insert(Account act);
}

• dao实现接口

package com.powernode.bank.dao.impl;
 
import com.powernode.bank.dao.AccountDao;
import com.powernode.bank.pojo.Account;
import jakarta.annotation.Resource;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;
 
@Repository
public class AccountDaoImpl implements AccountDao {
 
    @Resource
    private JdbcTemplate jdbcTemplate;
 
 
    @Override
    public Account selectByActno(String actno) {
        String sql = "select actno,balance from t_act where actno = ?";
        Account account = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(Account.class), actno);
        System.out.println("笑"+account);
        return account;
    }
 
    @Override
    public int update(Account act) {
        String sql = "update t_act set balance = ? where actno = ?";
        int update = jdbcTemplate.update(sql, act.getBalance(), act.getActno());
        return update;
    }
 
    @Override
    public int insert(Account act) {
        String sql = "insert into t_act values(?,?)";
        return jdbcTemplate.update(sql,act.getActno(),act.getBalance());
    }
}

• pojo实体类

package com.powernode.bank.pojo;
 
public class Account {
    private String actno;
    private Double balance;
 
    public Account() {
    }
 
    public Account(String actno, Double balance) {
        this.actno = actno;
        this.balance = balance;
    }
 
    public String getActno() {
        return actno;
    }
 
    public void setActno(String actno) {
        this.actno = actno;
    }
 
    public Double getBalance() {
        return balance;
    }
 
    public void setBalance(Double balance) {
        this.balance = balance;
    }
 
    @Override
    public String toString() {
        return "Account{" +
                "actno='" + actno + '\'' +
                ", balance=" + balance +
                '}';
    }
}

• service接口

package com.powernode.bank.service;
 
public interface AccountService {
    void transfer(String fromActno, String toActno, double money);
}

• service实现类

package com.powernode.bank.service.impl;
 
import com.powernode.bank.dao.AccountDao;
import com.powernode.bank.pojo.Account;
import com.powernode.bank.service.AccountService;
import jakarta.annotation.Resource;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
 
@Service
public class AccountServiceImpl implements AccountService {
    @Resource
    private AccountDao accountDao;
 
    //控制事务
    @Override
    public void transfer(String fromActno, String toActno, double money) {
        //查询余额
        Account fromAct = accountDao.selectByActno(fromActno);
        if (fromAct.getBalance() < money){
            throw new RuntimeException("余额不足!!");
        }
        //余额充足
        Account toAct = accountDao.selectByActno(toActno);
 
        //将内存中两个对象的余额先修改
        fromAct.setBalance(fromAct.getBalance() - money);
        toAct.setBalance(toAct.getBalance() + money);
 
        //数据库更新
        int count = accountDao.update(fromAct);
 
        //模拟异常
       /* String s = null;
        s.toString();*/
 
        count += accountDao.update(toAct);
 
 
 
        if (count !=2){
            throw new RuntimeException("转账失败,联系银行");
        }
    }
 
}

• spring.xml配置文件

<?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"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd
                           http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
                           http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">
 
    <!--组件扫描-->
    <context:component-scan base-package="com.powernode.bank"/>
 
    <!--配置数据源-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://192.168.1.41:3306/test"/>
        <property name="username" value="root"/>
        <property name="password" value="Abc123***"/>
    </bean>
 
    <!--配置JdbcTemplate-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
 
    <!--配置事务管理器-->
    <bean id="dataSourceTransactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
 
    <!--开启事务注解驱动器-->
<!--    <tx:annotation-driven  transaction-manager="dataSourceTransactionManager"/>-->
 
    <!--配置事务通知-->
    <tx:advice id="txAdvice" transaction-manager="dataSourceTransactionManager">
        <!--配置通知的transfer方法-->
        <tx:attributes>
            <tx:method name="transfer" propagation="REQUIRED" rollback-for="java.lang.Throwable"/>
        </tx:attributes>
    </tx:advice>
 
    <!--配置切面-->
    <aop:config>
        <!--切点-->
        <aop:pointcut id="txPointcut" expression="execution(* com.powernode.bank.service..*(..))"/>
        <!--切面 = 事务通知+切点-->
        <aop:advisor advice-ref="txAdvice" pointcut-ref="txPointcut"/>
    </aop:config>
 
</beans>

• 测试

    @Test
    public void testNoAnnotation() {
        ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("spring.xml");
        AccountService accountServiceImpl = classPathXmlApplicationContext.getBean("accountServiceImpl", AccountService.class);
        try {
            accountServiceImpl.transfer("act-001", "act-002", 10000);
            System.out.println("转账成功");
        } catch (Exception e){
            e.printStackTrace();
        }
    }

数据库截图