Interview questions: spread spring inside a transaction, which has several, namely what is
the point of coming to see @Transactional source
when using this annotation, in fact, there is a default value. It indicates that the current transaction is sure to use. If things do not currently exist or not, it will create a new thing = own thing. 'If the current method itself, the existence of things, you do not need to create an extra thing. It will join the existing additional things to go inside.
Propagation is an enumeration type
Ctrl + F12 you can put the contents of the current class method inside the show in the form of a list. Let us for quick browsing.
The new method for testing the result of an increase
to create additional service
this service is to call the main method of preservation.
Here is a comment, things spread a total of seven
We caught with one Required
In the api project which joined rely on Junit.
New test class
all do not write things, problems arise
in the database is now one of the data are not
being given.
Open things
Empty data within the database
to run the test class
is no data in the database
This is because there were things spread.
Although the method in which the child does not increase the @Transactional comment.
But things will be passed to the next method inside
later when our sub-method exception. Inside the two methods will be rolled back things.
Things opener methods
Methods of things a parent commented.
Run the test. Parent method was successfully saved. The parent level method does not object,
Open things the parent method, child method also opens
子方法的事物也是开启的
数据库内清空
运行测试类
依然报错
数据库依然没有数据
required总结
required多用于增删改的操作。
supports
从字面上看是一种支持。主要是用于做查询的。
父方法事务先注释掉
子方法的事务改为supports
清空数据库，运行测试类。
子方法用了supports。外层方法并没有事务，它就不使用事务，它是跟着外层走的
如果说外层使用了required。子方法还是supports
清空数据库，运行测试。---》数据库为空。事务进行了回滚。
supports总结
主要用于查询。
required和supports是两个最常用的
Mandatory
首先看它的注释。它是支持当前的事物的，如果不存在事物就会抛出异常，它强制了谁调用了我 ，谁就必须要有事物。它没有事务就会抛出异常。
把父方法的事物注释掉。
被调用放，也就是子方法使用mamdatory
运行测试
父方法的事物开启
运行测试，没有报Mandatory抛出的异常。这个错误是我自己代码的异常。
mandatory总结
