Spring事务实践

        大家都知晓的Spring的事物是基于动态机制的，支持CGLIB和JDK动态代理两种。如下所示：

一.CGLIB方式

        CGLIB代理无须必须实现接口。

package com.bijian.study.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.bijian.study.dao.IUserMapper;
import com.bijian.study.model.User;

@Service("userServiceAOP")
public class UserServiceAOP {

	private static final Logger log = LoggerFactory.getLogger(UserServiceImpl.class);
	
	@Autowired
	private IUserMapper mapper;
	
	@Transactional
	public int txUpdateUsersWhenException() { // 事务性
		return innerMethod();
	}
	
	private int innerMethod() {
		User user = new User(1, "Before exception");
		int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
		User user2 = new User(1, "After exception");
		int i = 1 / 0; // 抛出运行时异常，事务回滚
		int affectedCount2 = mapper.updateUser(user2); // 未执行
		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
		if (affectedCount == 1 && affectedCount2 == 1) {
			return 1;
		}
		return 0;
	}
}

        调试发现确实是CglibAop代理，此时事务是生效的。

二.JDK动态代理

package com.bijian.study.service;

public interface UserService {

	public int txUpdateUsersWhenException();
}

package com.bijian.study.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.bijian.study.dao.IUserMapper;
import com.bijian.study.model.User;

@Service("userService")
public class UserServiceImpl implements UserService {

	private static final Logger log = LoggerFactory.getLogger(UserServiceImpl.class);
	
	@Autowired
	private IUserMapper mapper;

	@Transactional
	public int txUpdateUsersWhenException() { // 事务性
		return innserMethod();
	}

	private int innserMethod() {
		User user = new User(1, "Before exception");
		int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
		User user2 = new User(1, "After exception");
		int i = 1 / 0; // 抛出运行时异常，事务回滚
		int affectedCount2 = mapper.updateUser(user2); // 未执行
		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
		if (affectedCount == 1 && affectedCount2 == 1) {
			return 1;
		}
		return 0;
	}
}

        调试发现确实是JDK动态代理，此时事务是生效的。

三.测试代码

package com.bijian.study.test;

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

import com.bijian.study.service.UserService;
import com.bijian.study.service.UserServiceAOP;

public class SpringIntegrationTest {
	
    private static ApplicationContext ctx;
    
    static {
    	ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
    }
  
    @Test  
    public void txUpdateUsersExceptionTest() {
    	
    	UserService userService = (UserService) ctx.getBean("userService");
        userService.txUpdateUsersWhenException();  
    }
    
    @Test  
    public void txUpdateUsersExceptionAOPTest() {
    	
    	UserServiceAOP userServiceAOP = (UserServiceAOP) ctx.getBean("userServiceAOP");
    	userServiceAOP.txUpdateUsersWhenException();  
    }
}

        applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:p="http://www.springframework.org/schema/p" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans 
                     http://www.springframework.org/schema/beans/spring-beans.xsd 
                     http://www.springframework.org/schema/tx 
                     http://www.springframework.org/schema/tx/spring-tx.xsd 
                     http://www.springframework.org/schema/aop 
                     http://www.springframework.org/schema/aop/spring-aop.xsd
                     http://www.springframework.org/schema/context 
                     http://www.springframework.org/schema/context/spring-context.xsd">

	<!-- 数据库配置文件 -->
	<context:property-placeholder location="classpath:/database.properties" />
	
	<!-- 数据源配置 -->
	<!--本示例采用DBCP连接池，应预先把DBCP的jar包复制到工程的lib目录下。 -->
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
		p:driverClassName="${driverClassName}" p:url="${url}" p:username="${user_name}"
		p:password="${password}" />
	
	<!-- sqlSessionFactory对象 -->
	<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
		<!--dataSource属性指定要用到的连接池 -->
		<property name="dataSource" ref="dataSource" />
		<!--configLocation属性指定mybatis的核心配置文件 -->
		<property name="configLocation" value="classpath:Configuration.xml" />
		<!-- 可以在Configuration.xml或此处配置映射文件，但其中不能有相同id的parameterMap, resultMap或sql等 -->
		<property name="mapperLocations" value="classpath*:com/bijian/study/model/*.xml" />
	</bean>

	<!-- 扫描指定包以获取映射器 -->
	<bean id="mapperConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.bijian.study.dao" />
	</bean>

	<!-- 事务管理器 -->
	<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource" />
	</bean>

	<!-- 事务注解驱动，标注@Transactional的类和方法将具有事务性 -->
	<tx:annotation-driven transaction-manager="txManager" />
    
	<bean id="userService" class="com.bijian.study.service.UserServiceImpl" />
	
	<bean id="userServiceAOP" class="com.bijian.study.service.UserServiceAOP" />
	
	<bean id="txTemplate" class="org.springframework.transaction.support.TransactionTemplate">
  		<constructor-arg type="org.springframework.transaction.PlatformTransactionManager" ref="txManager" />
  	</bean>
</beans>

        database.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://192.168.235.1:3306/hbatis?characterEncoding=utf8
user_name=bijian
password=123456

 

四.将@Transactional放到非外部直接调用的方法上

        将@Transactional放到非外部直接调用的方法上，调试发现无代理，事务失效。

1.修改CGLIB方式的服务方法

package com.bijian.study.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.bijian.study.dao.IUserMapper;
import com.bijian.study.model.User;

@Service("userServiceAOP")
public class UserServiceAOP {

	private static final Logger log = LoggerFactory.getLogger(UserServiceImpl.class);
	
	@Autowired
	private IUserMapper mapper;
	
	public int txUpdateUsersWhenException() { // 事务性
		return innerMethod();
	}
	
	@Transactional
	private int innerMethod() {
		User user = new User(1, "Before exception");
		int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
		User user2 = new User(1, "After exception");
		int i = 1 / 0; // 抛出运行时异常，事务回滚
		int affectedCount2 = mapper.updateUser(user2); // 未执行
		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
		if (affectedCount == 1 && affectedCount2 == 1) {
			return 1;
		}
		return 0;
	}
}

        @Transactional方法不是服务类的入口方法，无CGLIB代理，事务失效。

2.修改JDK动态代理方式的服务方法

package com.bijian.study.service;

public interface UserService {

	public int txUpdateUsersWhenException();
}

package com.bijian.study.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.bijian.study.dao.IUserMapper;
import com.bijian.study.model.User;

@Service("userService")
public class UserServiceImpl implements UserService {

	private static final Logger log = LoggerFactory.getLogger(UserServiceImpl.class);
	
	@Autowired
	private IUserMapper mapper;

	public int txUpdateUsersWhenException() { // 事务性
		return innserMethod();
	}

	@Transactional
	private int innserMethod() {
		User user = new User(1, "Before exception");
		int affectedCount = mapper.updateUser(user); // 因后面的异常而回滚
		log.info("{} new record was inserted successfully whose id: {}", affectedCount, user.getId());
		User user2 = new User(1, "After exception");
		int i = 1 / 0; // 抛出运行时异常，事务回滚
		int affectedCount2 = mapper.updateUser(user2); // 未执行
		log.info("{} new record was inserted successfully whose id: {}", affectedCount2, user.getId());
		if (affectedCount == 1 && affectedCount2 == 1) {
			return 1;
		}
		return 0;
	}
}

        @Transactional方法不是服务类的入口方法，无JDK动态代理，事务失效。

        测试前数据库中user表数据如下：

mysql> select * from user;
+----+--------+------+-------------------+
| id | name   | age  | address           |
+----+--------+------+-------------------+
|  1 | bijian |  120 | hangzhou,westlake |
+----+--------+------+-------------------+
1 row in set (0.00 sec)

        测试方法的innserMethod中虽然抛出异常，但事务并没有回滚，测试后数据库中user表数据如下：

mysql> select * from user;
+----+------+------+------------------+
| id | name | age  | address          |
+----+------+------+------------------+
|  1 | NULL |    0 | Before exception |
+----+------+------+------------------+
1 row in set (0.00 sec)