上一节中已经对Spring事物的一些基本概念和核心接口做了简介，并且演示了编程式事物实现，接下来介绍Spring中的另一种事物管理实现--声明式事物。
其底层建立在 AOP 的基础之上，对方法前后进行拦截，然后在目标方法开始之前创建或者加入一个事务，在执行完目标方法之后根据执行情况提交或者回滚事务。通过声明式事物，无需在业务逻辑代码中掺杂事务管理的代码，只需在配置文件中做相关的事务规则声明（或通过等价的基于标注的方式），便可以将事务规则应用到业务逻辑中。
声明式事物的实现方式有很多种，例如基于TransactionInterceptor、TransactionProxyFactoryBean、tx标签、Transactional注解等等。下面我们演示一下tx标签和Transactional的使用，为接下来的源码分析做好准备。
1.基于tx标签的声明式事物
- bean
package com.lyc.cn.v2.day08;
/**
* 账户接口
* @author: LiYanChao
* @create: 2018-11-07 18:38
*/
public interface AccountServiceImp {
void save() throws RuntimeException;
}
package com.lyc.cn.v2.day08;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 账户接口实现
* @author: LiYanChao
* @create: 2018-11-07 18:39
*/
public class AccountServiceImpl implements AccountServiceImp {
private JdbcTemplate jdbcTemplate;
private static String insert_sql = "insert into account(balance) values (100)";
@Override
public void save() throws RuntimeException {
System.out.println("==开始执行sql");
jdbcTemplate.update(insert_sql);
System.out.println("==结束执行sql");
System.out.println("==准备抛出异常");
throw new RuntimeException("==手动抛出一个异常");
}
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
}
- 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: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/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">
<!--事物管理器-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!--数据源-->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/my_test?useSSL=false&useUnicode=true&characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="liyanchao1989@"/>
</bean>
<!--jdbcTemplate-->
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"/>
</bean>
<!--业务bean-->
<bean id="accountService" class="com.lyc.cn.v2.day08.AccountServiceImpl">
<property name="jdbcTemplate" ref="jdbcTemplate"/>
</bean>
<!--tx标签配置-->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="save*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="query*" propagation="REQUIRED"/>
<tx:method name="*" read-only="true"/>
</tx:attributes>
</tx:advice>
<!--aop配置-->
<aop:config>
<aop:pointcut id="txPointcut" expression="execution(* com.lyc.cn.v2.day08..*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="txPointcut"/>
</aop:config>
</beans>
- 测试类及结果
@Test
public void test2() {
// 基于tx标签的声明式事物
ApplicationContext ctx = new ClassPathXmlApplicationContext("v2/day08.xml");
AccountServiceImp studentService = ctx.getBean("accountService", AccountServiceImp.class);
studentService.save();
}
==开始执行sql
==结束执行sql
==准备抛出异常
java.lang.RuntimeException: ==手动抛出一个异常
at com.lyc.cn.v2.day08.AccountServiceImpl.save(AccountServiceImpl.java:24)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
测试方法中手动抛出了一个异常，Spring会自动回滚事物，查看数据库可以看到并没有新增记录。
2.基于@Transactional注解的声明式事物
- bean
package com.lyc.cn.v2.day09;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
/**
* 账户接口
* @author: LiYanChao
* @create: 2018-11-07 18:38
*/
@Transactional(propagation = Propagation.REQUIRED)
public interface AccountServiceImp {
void save() throws RuntimeException;
}
package com.lyc.cn.v2.day09;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 账户接口实现
* @author: LiYanChao
* @create: 2018-11-07 18:39
*/
public class AccountServiceImpl implements AccountServiceImp {
private JdbcTemplate jdbcTemplate;
private static String insert_sql = "insert into account(balance) values (100)";
@Override
public void save() throws RuntimeException {
System.out.println("==开始执行sql");
jdbcTemplate.update(insert_sql);
System.out.println("==结束执行sql");
System.out.println("==准备抛出异常");
throw new RuntimeException("==手动抛出一个异常");
}
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
}
- 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:tx="http://www.springframework.org/schema/tx"
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">
<!--开启tx注解-->
<tx:annotation-driven transaction-manager="transactionManager"/>
<!--事物管理器-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
<!--数据源-->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/my_test?useSSL=false&useUnicode=true&characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="liyanchao1989@"/>
</bean>
<!--jdbcTemplate-->
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<property name="dataSource" ref="dataSource"/>
</bean>
<!--业务bean-->
<bean id="accountService" class="com.lyc.cn.v2.day09.AccountServiceImpl">
<property name="jdbcTemplate" ref="jdbcTemplate"/>
</bean>
</beans>
- 测试及结果
package com.lyc.cn.v2.day09;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* @author: LiYanChao
* @create: 2018-11-07 18:45
*/
public class MyTest {
@Test
public void test1() {
// 基于tx标签的声明式事物
ApplicationContext ctx = new ClassPathXmlApplicationContext("v2/day09.xml");
AccountServiceImp studentService = ctx.getBean("accountService", AccountServiceImp.class);
studentService.save();
}
}
==开始执行sql
==结束执行sql
==准备抛出异常
java.lang.RuntimeException: ==手动抛出一个异常
at com.lyc.cn.v2.day09.AccountServiceImpl.save(AccountServiceImpl.java:24)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
测试方法中手动抛出了一个异常，Spring会自动回滚事物，查看数据库可以看到并没有新增记录。
3.总结
以上两种方式都比较简单，只要配置正确就可以，当然很多细节并没有分析到，感兴趣的同学可以参考Spring的官方文档查看更多的细节化的配置，接下来我们就分析基于@Transactional注解的声明式事物的的源码实现。
