SpringBoot_事务总结

Springboot 事务

1. 打印SQL 日志的两种配置方式

[1]通过配置包的log等级来打印SQL日志，但这种不会打印出事务日志

logging.level.com.grady.mybatisdemo.mapper=DEBUG

[2] 配置mybatis的logImpl属性，好处是会输出事务日志

mybatis.configuration.logImpl=org.apache.ibatis.logging.stdout.StdOutImpl

PS：rollbackFor默认是非受检异常回滚，配置rollbackFor = Exception.class改成所有异常回滚

2 成功和失败的日志信息

[1]. 一次查询成功的日志

代码

    @Transactional(rollbackFor = Exception.class)

    @PostMapping("/allUser")

    public PageInfo<User> allUser() {

        PageHelper.startPage(2,3);

        List<User> users = userMapper.findAllUser();

        PageInfo<User> pageInfo = new PageInfo<>(users);

        return pageInfo;

    }

Creating a new SqlSession

Registering transaction synchronization for SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7580f2b1]

Cache Hit Ratio [SQL_CACHE]: 0.5

JDBC Connection [HikariProxyConnection@2138610113 wrapping com.mysql.cj.jdbc.ConnectionImpl@55855042] will be managed by Spring

==>  Preparing: SELECT count(0) FROM user_copy

==> Parameters:

<==    Columns: count(0)

<==        Row: 5

<==      Total: 1

==>  Preparing: SELECT * FROM user_copy LIMIT ?, ?

==> Parameters: 3(Integer), 3(Integer)

<==    Columns: user_id, name, password, token, ownapps, role_id

<==        Row: 4, testUser4, 4, a, 2, 4

<==        Row: 5, testUser5, 5, a, 4, 5

<==      Total: 2

Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7580f2b1]

Transaction synchronization committing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7580f2b1]

Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7580f2b1]

Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7580f2b1]

[2]. 一次抛异常回滚的日志

代码：

    @Transactional(rollbackFor = Exception.class)

    @Override

    public Integer insertUser(User user) throws BusinessException {

        try {

            List<User> users = userMapper.findAllUser();

            Integer result = userMapper.insert(user);

            if (true) {

                int i = 1 / 0; //这里抛RuntimeException异常

            }

            return result;

        } catch (Exception e) {

            e.printStackTrace();

            throw new BusinessException("访问数据库失败", 1001);// 被我catch然后改为受检异常抛出

        }

    }

Creating a new SqlSession

Registering transaction synchronization for SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383]

JDBC Connection [HikariProxyConnection@1016081606 wrapping com.mysql.cj.jdbc.ConnectionImpl@3560cd99] will be managed by Spring

==>  Preparing: SELECT * FROM user_copy

==> Parameters:

<==    Columns: user_id, name, password, token, ownapps, role_id

<==        Row: 1, testUser1, 1, a, 2, 1

<==        Row: 2, testUser2, 2, a, 2, 2

<==        Row: 3, testUser3, 3, a, 2, 3

<==        Row: 4, testUser4, 4, a, 2, 4

<==        Row: 5, testUser5, 5, a, 4, 5

<==      Total: 5

Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383]

Fetched SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383] from current transaction

==>  Preparing: INSERT INTO user_copy ( name, password, token, ownapps, role_id ) VALUES ( ?, ?, ?, ?, ? )

==> Parameters: jiang(String), zhongjin(String), abcd(String), o(String), 2(Long)

<==    Updates: 1

Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383]

Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383]

Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2e775383]

ps：此异常从被Transactional注解的方法中抛出后就立即回滚并关闭SQLSession了

总结1：SpringBoot使用事务就是这么容易，只要在对应的方法上加上注解就可以了

3. 事务冲突问题

当使用事务增强来为一些匹配的方法加上事务，如果在这些方法调用其他被@Transactional绑定的方法时，会抛出事务异常，但对数据不会有影响**

比如：

事务增强加在了Controller上，controller调用Manager的方法，而Manager方式使用了@Transactional注解，这是会抛一下错误（经测试如果加载controller自己上没有问题，在调用链上才有问题）

抛出的异常是

org.springframework.transaction.UnexpectedRollbackException: Transaction rolled back because it has been marked as rollback-only

	at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:873) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]

	at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:710) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]

[1] 使用事务增强的两种方式

①XML 方式(然后使用@ImportResource("classpath:transaction.xml")引入)

<?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: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.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">

  <bean id="txManager"

    class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

    <property name="dataSource" ref="dataSource" ></property>

  </bean>

  <tx:advice id="cftxAdvice" transaction-manager="txManager">

    <tx:attributes>

      <tx:method name="query*" propagation="SUPPORTS" read-only="true" ></tx:method>

      <tx:method name="get*" propagation="SUPPORTS" read-only="true" ></tx:method>

      <tx:method name="select*" propagation="SUPPORTS" read-only="true" ></tx:method>

      <tx:method name="*" propagation="REQUIRED" rollback-for="Exception" ></tx:method>

    </tx:attributes>

  </tx:advice>

   <aop:config>

    <aop:pointcut id="allManagerMethod" expression="execution (* com.grady.mybatisdemo..controller.*.*(..))" />

    <aop:advisor advice-ref="txAdvice" pointcut-ref="allManagerMethod" order="0" />

  </aop:config>

</beans>

// read-only="true" 表示这个方法只能读数据库，写会报错

这个增强表示，controller下的所有方法都在范围内，如果满足tx:method 的条件则加上事务

②代码配置方式

@Configuration

public class TransactionAdviceConfig {

    private static final String AOP_POINTCUT_EXPRESSION = "execution (* com.grady.mybatisdemo..controller.*.*(..))";

    @Autowired

    private PlatformTransactionManager transactionManager;

    @Bean(name = "txAdvice")

    public TransactionInterceptor txAdvice() {

        Properties properties = new Properties();

      	// readOnly 表示这个方法只能读数据库，写会报错

        properties.setProperty("get*", "PROPAGATION_REQUIRED,-Exception,readOnly");

        properties.setProperty("add*", "PROPAGATION_REQUIRED,-Exception");

        properties.setProperty("save*", "PROPAGATION_REQUIRED,-Exception");

        properties.setProperty("update*", "PROPAGATION_REQUIRED,-Exception");

        properties.setProperty("delete*", "PROPAGATION_REQUIRED,-Exception");

      	//"PROPAGATION_REQUIRED,  -Exception"这里有空格不要紧

        properties.setProperty("insert*", "PROPAGATION_REQUIRED,-Exception");

        TransactionInterceptor transactionInterceptor = new TransactionInterceptor(transactionManager, properties);

        return transactionInterceptor;

    }

    @Bean

    public Advisor txAdviceAdvisor() {

        AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();

        pointcut.setExpression(AOP_POINTCUT_EXPRESSION);

        return new DefaultPointcutAdvisor(pointcut, txAdvice());

    }

}

经测试 properties.setProperty("insert*", "PROPAGATION_REQUIRED,-Exception"); "PROPAGATION_REQUIRED,-Exception" 每个关键字的两侧有空格不要紧，加载前会自动trim

代码的方式要更加优雅，可以利用到编译器在编译期做检查，XML只有运行时才能知道是对是错，代码的方式相对会更好一些

总结：

建议不要使用事务增强，因为你还得去记哪些方法名会被加事务，哪些不会，也会影响到你对方法的命名，一个表意的函数名是非常重要的，我觉得这种方式是得不偿失的。
建议直接使用@Transactional 来为方法加事务，这样一眼就可以知道当前方法有没有事务。
最好不要用了事务增强，又用@Transactional，因为如果两个方法加在了同一个方法链上，一旦抛异常回滚是会报UnexpectedRollbackException异常错误的
如果在调用链很后的地方抛出的异常，到被事务增强的函数时，此时一定要接着抛出，否则不会回滚，因为内部消化的异常等于正常操作，不会回滚