本文延续上一文章（spring事务传播特性实验（1）：数据准备），在已经准备好环境的情况下，做如下的实验，以验证spring传播特性，加深对spring传播特性的理解。
本次主要验证PROPAGATION_REQUIRED的传播特性：
TransactionDefinition.PROPAGATION_REQUIRED
TransactionDefinition.PROPAGATION_REQUIRED：根据spring的定义PROPAGATION_REQUIRED即需要事务的支持，如果没有的情况下会自己创建一个新的事务
我们进行如下测试：
A、外部有事务的情况下：http://localhost:8080/test1?type=0
DEBUG 137 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Acquired Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] for JDBC transaction
DEBUG 143 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Switching JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] to manual commit
INFO 149 INFO com.sapling.project.module.biz.TransactionTest - [outerTransaction]current transaction name : outerTransaction
INFO 151 INFO com.sapling.project.module.biz.TransactionTest - {name:0}
DEBUG 263 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Participating in existing transaction
INFO 263 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction 0 ]current transaction name : outerTransaction
INFO 263 INFO com.sapling.project.module.biz.TransactionTest - {name:0}
INFO 267 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction]current transaction outerTransaction commit.
DEBUG 268 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Initiating transaction commit
DEBUG 268 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Committing JDBC transaction on Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465]
DEBUG 274 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Releasing JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] after transaction
DEBUG 274 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource
INFO 275 INFO com.sapling.project.module.biz.TransactionTest - [outerTransaction]current transaction null commit.
从日志中我们可以看到这样的记录：Participating in existing transaction，加入到一个已经存在的事务中。
数据表插入成功
+----+----------+------+--------+ | id | name | sex | status | +----+----------+------+--------+ | 8 | 0-true | NULL | NULL | | 9 | i-0-true | NULL | NULL |
B、外部没有事务的情况下：http://localhost:8080/test3?type=0
INFO 093 INFO com.sapling.project.module.biz.TransactionTest - [outerTransaction] did not have transaction
INFO 094 INFO com.sapling.project.module.biz.TransactionTest - {name:0}
DEBUG 094 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource
DEBUG 104 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource
DEBUG 104 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Creating new transaction with name [null]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
DEBUG 104 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Acquired Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] for JDBC transaction
DEBUG 104 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Switching JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] to manual commit
INFO 106 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction 0 ]current transaction name : null
INFO 107 INFO com.sapling.project.module.biz.TransactionTest - {name:0}
DEBUG 111 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Initiating transaction commit
DEBUG 111 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Committing JDBC transaction on Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465]
DEBUG 118 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Releasing JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@1512c465] after transaction
DEBUG 119 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource
INFO 119 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction]current transaction null commit.
Creating new transaction with name [null]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT，创建一个新的事务，传播特性为PROPAGATION_REQUIRED，隔离级别为默认。
数据表插入成功
mysql> select * from sys_user
-> ;
+----+----------+------+--------+
| id | name | sex | status |
+----+----------+------+--------+
| 8 | 0-true | NULL | NULL |
| 9 | i-0-true | NULL | NULL |
| 10 | o-0-true | NULL | NULL |
| 11 | i-0-true | NULL | NULL |
+----+----------+------+--------+
4 rows in set (0.00 sec)
C、外部有事务，但内部异常的情况下：
系统报500错误，日志如下：
165 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Creating new transaction with name [null]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
172 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Acquired Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5d7163af] for JDBC transaction
172 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Switching JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5d7163af] to manual commit
174 INFO com.sapling.project.module.biz.TransactionTest - [outerTransaction]current transaction name : outerTransaction
174 INFO com.sapling.project.module.biz.TransactionTest - {name:o-0-true}
178 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Participating in existing transaction
178 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction 0 ]current transaction name : outerTransaction
178 INFO com.sapling.project.module.biz.TransactionTest - {name:11111111111111111111111111111}
284 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Participating transaction failed - marking existing transaction as rollback-only
284 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Setting JDBC transaction [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5d7163af] rollback-only
284 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction ]current transaction outerTransaction rollback. 284 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Global transaction is marked as rollback-only but transactional code requested commit 284 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Initiating transaction rollback 284 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Rolling back JDBC transaction on Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5d7163af] 319 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Releasing JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5d7163af] after transaction 319 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 326 DEBUG org.springframework.web.servlet.DispatcherServlet - Could not complete request org.springframework.transaction.IllegalTransactionStateException: Transaction is already completed - do not call commit or rollback more than once per transaction
可以看到，事务在在内部方法中就直接回滚了，整个事务已经完成了，外部事务再在做回滚操作的时候，就报错了，这里可以在回滚操作之前加上!status.isCompleted()检查事务是不是完成了，完成了则不需要再回滚了。
检查数据库，可以看出事务整个失败了，不管是内部方法还是外部方法的数据都没有插入成功：
mysql> select * from sys_user; +----+----------+------+--------+ | id | name | sex | status | +----+----------+------+--------+ | 8 | 0-true | NULL | NULL | | 9 | i-0-true | NULL | NULL | | 10 | o-0-true | NULL | NULL | | 11 | i-0-true | NULL | NULL | +----+----------+------+--------+ 4 rows in set (0.00 sec)
D、外部没有事务，内部执行失败：
.964 INFO com.sapling.project.module.biz.TransactionTest - [outerTransaction] did not have transaction
.964 INFO com.sapling.project.module.biz.TransactionTest - {name:0-true}
.964 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource
.973 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource
.973 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Creating new transaction with name [null]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
.973 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Acquired Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5b773cec] for JDBC transaction
.973 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Switching JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5b773cec] to manual commit
.974 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction 0 ]current transaction name : null
.974 INFO com.sapling.project.module.biz.TransactionTest - {name:11111111111111111111111111111}
.978 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Initiating transaction rollback
.978 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Rolling back JDBC transaction on Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5b773cec]
.982 DEBUG o.s.jdbc.datasource.DataSourceTransactionManager - Releasing JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@5b773cec] after transaction
.982 DEBUG o.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource
.982 INFO com.sapling.project.module.biz.TransactionTest - [doInnerTransaction ]current transaction null rollback.
数据库表查询结果：
mysql> select * from sys_user; +----+----------+------+--------+ | id | name | sex | status | +----+----------+------+--------+ | 8 | 0-true | NULL | NULL | | 9 | i-0-true | NULL | NULL | | 10 | o-0-true | NULL | NULL | | 11 | i-0-true | NULL | NULL | | 16 | 0-true | NULL | NULL | +----+----------+------+--------+ 5 rows in set (0.00 sec)
可以看出来，内部事务的失败不同事务下的插入操作。
由如上的几个执行结果可以看出来，Required传播模式下的事务，会在已经存在事务的情况下加入已有的事务，按照现有事务的流程执行，没有事务的情况下，新建一个事务执行，其执行的结果对其他的事务不产生影响。