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。
