Spring事务管理——回滚(rollback-for)控制

1.代码中事务控制的3种方式[1]

• 编程式事务：就是直接在代码里手动开启事务，手动提交，手动回滚。优点就是可以灵活控制，缺点就是太麻烦了，太多重复的代码了。
• 声明式事务：就是使用SpringAop配置事务，这种方式大大的简化了编码。需要注意的是切入点表达式一定要写正确。
• 注解事务：直接在Service层的方法上面加上@Transactional注解，个人比较喜欢用这种方式。

2.事务不回滚的原因

    在工作中，看过别人写的代码出现了事务不回滚的现象。当然，事务不回滚的都是采用的声明式事务或者是注解事务；编程式事务都是自己写代码手动回滚的，因此是不会出现不回滚的现象。

 

    再说下声明式事务和注解事务回滚的原理：当被切面切中或者是加了注解的方法中抛出了RuntimeException异常时，Spring会进行事务回滚。默认情况下是捕获到方法的RuntimeException异常，也就是说抛出只要属于运行时的异常（即RuntimeException及其子类）都能回滚；但当抛出一个不属于运行时异常时，事务是不会回滚的。

 

    下面说说我经常见到的3种事务不回滚的产生原因：

• （1）声明式事务配置切入点表达式写错了，没切中Service中的方法
• （2）Service方法中，把异常给try catch了，但catch里面只是打印了异常信息，没有手动抛出RuntimeException异常
• （3）Service方法中，抛出的异常不属于运行时异常（如IO异常），因为Spring默认情况下是捕获到运行时异常就回滚

代码实践

1.不捕获异常(一般处理方式)[2]

代码，其中contentMappger.updateWithErrTest(31L); 是SQL语句错误，用来测试回滚。

    /**
     * 删除多条记录
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        return ShopResult.ok();
    }

运行结果：报错，事务发生了回滚，即由于错误代码，前面的for循环删除记录事务被回滚了。

### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
; bad SQL grammar []; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1] with root cause
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
    at com.mysql.jdbc.Util.getInstance(Util.java:381)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1030)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3536)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3468)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1957)
    ..................
    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
    at com.sun.proxy.$Proxy35.updateWithErrTest(Unknown Source)
    at com.shop.manager.service.impl.ContentServiceImpl.deleteContentGroup(ContentServiceImpl.java:94)
    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)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
    .......

2. 捕获异常，但不处理，不抛出

代码

    /**
     * 删除多条记录
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        try {
            contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        } catch (Exception e) {
            //捕获异常，但不处理
            System.out.println("-----nothing to do-------");
        }
        return ShopResult.ok();
    }

运行结果：事务提交，未回滚。 

### The error occurred while setting parameters
### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
]
-----nothing to do-------
2017-06-18 14:27:59,493 [http-bio-8080-exec-4] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization committing SqlSession //(事务提交)
[org.apache.ibatis.session.defaults.DefaultSqlSession@616a85a9]

3. 捕获异常，并抛出RuntimeException异常

Spring碰到Unchecked Exceptions都会回滚，不仅是RuntimeException，也包括Error。 
代码

    /**
     * 删除多条记录
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        try {
            contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        } catch (Exception e) {
            System.out.println("----throw Exception-----");
            throw new RuntimeException();
        }
        return ShopResult.ok();
    }

运行结果：如预期的一样，抛出RuntimeException，事务发生回滚。

### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
]
----throw Exception-----
2017-06-18 14:21:27,928 [http-bio-8080-exec-1] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3ef56e3a]
...............
2017-06-18 14:21:27,941 [http-bio-8080-exec-1] [org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver]-[DEBUG] Resolving exception from handler [public com.shop.common.pojo.ShopResult com.shop.manager.controller.ContentController.deleteContentGroup(java.lang.String)]: java.lang.RuntimeException
2017-06-18 14:21:27,941 [http-bio-8080-exec-1] [org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver]-[DEBUG] Resolving exception from handler [public com.shop.common.pojo.ShopResult com.shop.manager.controller.ContentController.deleteContentGroup(java.lang.String)]: java.lang.RuntimeException
2017-06-18 14:21:27,942 [http-bio-8080-exec-1] [org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver]-[DEBUG] Resolving exception from handler [public com.shop.common.pojo.ShopResult com.shop.manager.controller.ContentController.deleteContentGroup(java.lang.String)]: java.lang.RuntimeException
2017-06-18 14:21:27,942 [http-bio-8080-exec-1] [org.springframework.web.servlet.DispatcherServlet]-[DEBUG] Could not complete request
java.lang.RuntimeException
    at com.shop.manager.service.impl.ContentServiceImpl.deleteContentGroup(ContentServiceImpl.java:98)  //异常
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

4.捕获异常，并继续抛出原捕获的异常

代码：

    /**
     * 删除多条记录
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        try {
            contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        } catch (Exception e) {
            //捕获异常，继续抛出
            System.out.println("-----throw Exception-------");
            throw e;
        }
        return ShopResult.ok();
    }

运行结果：抛出异常，事务发生回滚

### The error occurred while setting parameters
### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
]
-----throw Exception-------
2017-06-18 14:36:25,308 [http-bio-8080-exec-9] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@45fe0f70]
2017-06-18 14:36:25,308 [http-bio-8080-exec-9] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization closing SqlSession //事务回滚
[org.apache.ibatis.session.defaults.DefaultSqlSession@45fe0f70]

5. 捕获异常，并抛出新new的异常(或自定义Exception异常) new Exception

代码：

    /**
     * 删除多条记录
     * @throws Exception 
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) throws Exception {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        try {
            contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        } catch (Exception e) {
            //捕获异常，抛出新异常
            System.out.println("-----throw new Exception(e)-------");
            throw new Exception(e);
        }       
        return ShopResult.ok();
    }

运行结果：事务提交，未回滚。（Spring的默认回滚异常类型不包括Exception）

### The error occurred while setting parameters
### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
]
-----throw new Exception(e) -------
2017-06-18 14:43:16,098 [http-bio-8080-exec-10] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization committing SqlSession //事务提交
[org.apache.ibatis.session.defaults.DefaultSqlSession@32c4821]
2017-06-18 14:43:16,098 [http-bio-8080-exec-10] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@32c4821]

6. 在事务配置中没有设置rollback-for异常类型为Exception

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

    <!-- 通知 -->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
        <!-- 事务行为控制 -->
        <tx:attributes>
            <tx:method name="save" propagation="REQUIRED" rollback-for="Exception"/>
            <tx:method name="insert*" propagation="REQUIRED"  rollback-for="Exception"/>
            <tx:method name="add*" propagation="REQUIRED"  rollback-for="Exception"/>
            <tx:method name="create*" propagation="REQUIRED"  rollback-for="Exception"/>
            <tx:method name="delete*" propagation="REQUIRED"  rollback-for="Exception"/>
            <tx:method name="update*" propagation="REQUIRED"  rollback-for="Exception"/>
            <tx:method name="find*" propagation="SUPPORTS" read-only="true" />
            <tx:method name="select*" propagation="SUPPORTS" read-only="true" />
            <tx:method name="get*" propagation="SUPPORTS" read-only="true" />
        </tx:attributes>
    </tx:advice>
    <!-- 配置切面 -->
    <aop:config>
        <aop:advisor advice-ref="txAdvice" pointcut="execution(* com.shop.manager.service.*.*(..))" />
    </aop:config>

    /**
     * 删除多条记录
     * @throws Exception 
     */
    @Override
    public ShopResult deleteContentGroup(String[] ids) throws Exception {
        if (null == ids || ids.length == 0)
        {
            return ShopResult.error();
        }
        for (String idStr : ids)
        {
            Long id = new Long(idStr);
            contentMappger.deleteByPrimaryKey(id);
        }
        try {
            contentMappger.updateWithErrTest(31L);   //错误代码，SQL语句错误。用来测试事务，看是否回滚
        } catch (Exception e) {
            //捕获异常，继续抛出
            System.out.println("-----throw new Exception-------");
            throw new Exception("---自定义Exception，事务中已配置rollback-for---");
        }
        return ShopResult.ok();
    }

运行结果：如预期一样发生回滚

### The error may involve com.shop.manager.mapper.TbContentMapper.updateWithErrTest-Inline
### The error occurred while setting parameters
### SQL: delete form tb_content    where kid = ?
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'tb_content
    where kid = 31' at line 1
]
-----throw new Exception-------
2017-06-18 15:07:02,273 [http-bio-8080-exec-8] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@f177061]
2017-06-18 15:07:02,273 [http-bio-8080-exec-8] [org.mybatis.spring.SqlSessionUtils]-[DEBUG] Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@f177061]

---

总结：

1. Spring事务管理是根据异常来进行回滚操作；
2. Spring与Mybatis整合时，虽然在Service方法中并没有check异常，但是如果数据库有异常发生，默认会进行事务回滚。
3. Spring 如果不添加rollbackFor等属性，Spring碰到Unchecked Exceptions都会回滚，不仅是RuntimeException，也包括Error。
4. 如果在事务方法中捕获异常并进行处理，一定要继续抛出异常并在Spring事务管理中进行rollbak-for配置。

原文出处：

[1] zeng1994, 浅谈Spring中的事务回滚, https://www.cnblogs.com/zeng1994/p/8257763.html
[2] JeangLee, Spring事务管理——回滚(rollback-for)控制, https://blog.csdn.net/ljyhust/article/details/73431968?locationNum=5&fps=1