问题
Our web project uses spring3, Jpa (hibernate).
To save CRUD and other commonly used methods, we made our repositories sub-classes of spring JpaRepository.
Sometimes I just injected repositories to Controller, it is convenient for those simple (or none) business logic read-only data access. e.g. list all objects of an entity type in view... I knew that all these should be done in a service layer with transaction scope, but it is really convenient.
Now comes a rule: controller layer must via Service access data layer. Injecting Repositories into Controller is not allowed.
for example:
I have an Entity: Country.java
And I have interface CountryRepository extends JpaRepository<Country, Long>
Also I have CountryService and CountryServiceImpl, which has countryRepository injected. Then I have to create findAll, findOne, count, findAll(with sorting).... methods, and those implementation is nothing more than return countryRepository.findAll() countryRepository.findOne(id) countryRepository.count()...
And for each entity I have to do the same again and again...
Is it possible that in service layer save those methods using a generic way?
回答1:
Only expose services that your application really uses. I doubt you need a findAll or a count for every entity.
The fact that the implementation of these methods is very simple is a good thing: you won't have any difficulty implementing and testing them. If they become more complex, and need several repository method calls and a bit of business logic, you'll be happy to just have to modify the method, and not change all your design.
来源：https://stackoverflow.com/questions/7658899/how-to-save-simple-crud-codes-in-a-service-just-like-genericdao-jparepository