什么是声明式事务？Java中

Posted 2023-04-22

参考技术A 你说的是集成spring和hibernate所使用的声明式事务吧，就是在没用spring集成前，与数据库交互的增删改操作都需要开启事务再提交对吧，现在这些事情全交给spring做了，你只需要在applicationContext文件中导入相应命名空间再配置一下就可以了。预知详情，百度一下你就知道。。

马士兵Spring-声明式事务管理-XML

1.com.cy.model中User.java  和 Log.java 实体 和上一节一样；

2.DAO的实现类com.cy.dao.impl中的UserDAOImpl、LogDAOImpl.java和上一节一样；

3.UserService.java:

package com.cy.service;

import javax.annotation.Resource;

import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import com.cy.dao.LogDAO;
import com.cy.dao.UserDAO;
import com.cy.model.Log;
import com.cy.model.User;

@Component("userService")
public class UserService {
    
    @Resource
    private UserDAO userDAO;  
    
    @Resource
    private LogDAO logDAO;
    
    public void init() {
        System.out.println("init");
    }
    
    public User getUser(int id) {
        return null;
    }
    
    /**
     * 插入一个用户的同时，记录一条日志
     */
    public void add(User user) {
        userDAO.save(user);
        Log log = new Log();
        log.setMsg("a user saved!");
        logDAO.save(log);
    }
    
    public UserDAO getUserDAO() {
        return userDAO;
    }
    
    public void setUserDAO( UserDAO userDAO) {
        this.userDAO = userDAO;
    }
    
    public void destroy() {
        System.out.println("destroy");
    }
}

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4.beans.xml中事务管理的配置：

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd
           http://www.springframework.org/schema/aop
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
           http://www.springframework.org/schema/tx
           http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
           
    <context:annotation-config />
    <context:component-scan base-package="com.cy"/>
    
    <!-- 如果下面使用到了占位符的方式，请在locations下面去找 -->
    <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <value>classpath:jdbc.properties</value>
        </property>
    </bean>

    <bean id="dataSource" destroy-method="close" class="org.apache.commons.dbcp.BasicDataSource">
        <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> 
    
    <!-- 初始化SessionFactory -->
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan">
            <list>
                <value>com.cy.model</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>
    
    <bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
          <property name="sessionFactory" ref="sessionFactory" />
    </bean>
    
    <aop:config>
        <aop:pointcut id="bussinessService" expression="execution(public * com.cy.service..*.*(..))" />
        <aop:advisor pointcut-ref="bussinessService" advice-ref="txAdvice" />
    </aop:config>
    
    <tx:advice id="txAdvice" transaction-manager="txManager">
        <tx:attributes>
            <tx:method name="getUser" read-only="true" />
            <tx:method name="add*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>
    
</beans>

5.测试代码：

package com.cy.service;

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

import com.cy.model.User;

public class UserServiceTest {
    
    @Test
    public void testAdd() throws Exception {
        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml");
        UserService service = (UserService)ctx.getBean("userService");
        System.out.println(service.getClass());
        service.add(new User());
        ctx.destroy();
    }
}

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1）正常情况下测试，没有异常抛出，ok，user和log都插入；

2）在LogDAOImpl中的save方法中手动抛出一个异常，插入失败；user没有插入成功，已经回滚了。