spring boot 事務不起做用

使用springboot 配置了

@EnableTransactionManagement
@Transactional

可是事務根本不起做用。

首先第一點：Spring的AOP事務管理默認是針對RunTimeException回滾，這個例外是unchecked exceptions。unchecked exception異常都是RuntimeException的子類。
若是遇到checked exceptions意外就不回滾。
如何改變默認規則：
1 讓checked例外也回滾：在整個方法前加上 @Transactional(rollbackFor=Exception.class)
2 讓unchecked例外不回滾： @Transactional(notRollbackFor=RunTimeException.class)

checked exceptions 其必須被 try{}catch語句塊所捕獲,或者在方法簽名裏經過throws子句聲明.受檢查的異常必須在編譯時被捕捉處理。

unchecked exceptions 須要程序員本身分析代碼決定是否捕獲和處理,好比 空指針,被0除...

 

其次是第二點

查看數據庫中，表的引擎方式。

1      查看mysql如今已提供什麼存儲引擎: show engines;  只有InnoDB是支持事務的

mysql>  show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

2      查看本身的表的引擎方式   show create table 表名;

         或者 show table status from db_name where name='table_name';

mysql> show create table user;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                          |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| user  | CREATE TABLE `user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `grade_id` bigint(20) DEFAULT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8 |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

mysql> show table status from test where name='user';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time         | Update_time         | Check_time | Collation       | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
| user | MyISAM |      10 | Dynamic    |    1 |             20 |          20 | 281474976710655 |         2048 |         0 |              2 | 2018-04-27 21:50:12 | 2018-04-28 18:43:10 | NULL       | utf8_general_ci |     NULL |                |         |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+

         能夠看到  user表是MyISAM引擎建立的，不支持事務。

3  修改表爲InnoDB引擎  alter table table_name engine=innodb;