I know how to implement spring data custom repository i.e. an interface e.g. CustomRepository and an implementation class e.g. CustomRepositoryImpl. What i dislike is the Impl in the class name. Its not a pronouncable word. Is there any alternative?
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I am trying to implement a Spring Boot REST API but I was asked to use a interface as dependency but no impl, and I don't know how to achieve this. The way I implemented was to have service classes for my entities and there I would just call the repository in my methods. I would like an example of implementation like this.
I watched some youtube tutorials but they all used impl classes
Your controller should have a field of your interface type, with the injecting annotation (in spring it's #Autowired). The DI framework will do the heavy-lifting on startup and inject the correct implementation at runtime
#Controller
public class MyController {
#Autowired
private MyInterface myInterface;
....
}
For this to work, your framework needs to recognize the concrete class. In spring you can achieve this in multiple ways - scanning package paths, xml configuration files and more.
Check the spring documentation to see which way suits you best
i am new to spring
in my spring web project DAO and service they created the interface and implementing it created class. can we liminate interface.
The whole point of using interface is to create abstraction. When you call you DAO from Service, your service is not aware of the actual implementation of DAO/ cases in which you have multiple implementations of your DAO interface, your service is not aware of the actual impl being used.
With spring you will use - Autowire to inject the dependency. You will refer your Dependency using interface.
#Component/#Service
class ServiceImpl {
#Autowired
private DAOInterface dao;
// Rest of code
}
Spring knows - to create the instance of this ServiceImpl it needs to inject a concrete impl of DAOInterface type. In case you have concrete implementation, it does so. In case you have multiple impls - you need to define by bean name which implementation you need using #Qualifier.
Interface is kind of a contract for your impl classes. Other than abstracting the actual impl, it helps you decoupling the layers by not directly having a dependency on the concrete classes. This is a good design pattern
Im trying to upgrade my project from spring-boot-1.4.3.RELEASE to spring-boot-1.5.9.RELEASE.
In the 1.4.3.RELEASE the way I have used my custom implementation of repositories is as follow:
Made an interface MyCustomRepositroy that extends JpaRepository
Had a class MyCustomRepositoryImpl that implements MyCustomRepositroy and SimpleJpaRepository. In that class I have changed the behavior of
the of save, find and delete methods, because I needed a
ceratin behavior for entitys of certain type (lets say that I need a
custom save for all entitys that implements Special interface)
I made a MyCustomJpaRepositoryFactoryBean that extends JpaRepositoryFactoryBean. In that factory, I've overridden createRepositoryFactory and gave it my MyRepositoryFactory implementation.
In MyRepositoryFactory implementation I've overridden the getTargetRepository, and getRepositoryBaseClass.In these methods, I check if the entity is of type Special, and if so, I return MyCustomRepositoryImpl, otherwise I return SimpleJpaRepository.
Also, I can get the beanFactory in my MyCustomRepositoryImpl class because I call my own constructor of MyCustomRepositoryImpl that has also a beanFactory parameter via getTargetRepositoryViaReflection.
Now, with the new version (that uses spring-data-commons-1.13.9.RELEASE), I cannot override the Factory class, and hence can't decide for each entitiy which implementation to give, and have no way to get the beanFactory.
Is there any way I can get what I want?
Sorry for the mess, but I cannot post my code here.
P.S - my project is a spring based library, so I can't do anything to the entitys because my clients declare them, all I know that some entitys implement the Special interface and some don't
I am trying to figure out what happened in 1.5.9.RELEASE, but in the meantime, just as a fyi - 1.5.6.RELEASE works ok.
I am having the same issue when trying to update from 1.5.6.RELEASE to 1.5.9.RELEASE
I am using spring data JPA repository, my requirement is when i call repository class methods in service class it should show only custom methods like addUser(X,Y) instead of save().
Few things i understand, implementation of spring repository is provided by spring framework at runtime, So we cannot provide out own implementation. (This will overhead).
All methods in JPARepository is public only, so its obivious when we implement this interface all methods will be visible through out.
I am thinking of using DAO and Repository both at same time. DAO will provide custom function signature and repository will implement DAO interface.
Any Hack ?
If you don't want the methods from JpaRepository or CrudRepository, don't extend those but just Repository instead. It is perfectly fine to have a repository interface like
MyVeryLimitedRepository extends Repository<User, Long> {
User findByName(String name);
}
Of course methods like addUser(X,Y) will need a custom implementation.
You can very well use DAO pattern in this case .
By implementing DAO Pattern in Service Class
You create a wrapper between Service and Repository.
You can custom code your DAO layer to only expose custom methods to service layer
I am reading the Spring Hibernate CRUD tutorial from this url
http://viralpatel.net/blogs/spring3-mvc-hibernate-maven-tutorial-eclipse-example/
Please can anyone tell me why in ContactController.java, ContactService interface is autowired instead of the class ContactServiceImpl.
Similarly in ContactServiceImpl ContactDAO interface is injected. Shouldn't we supposed to inject class instead of an interface?
When your code is dependent on interface and its implementation is injected by Spring, your code becomes decoupled with the implementation. This has an advantage that now you can swap in a different implementation without having to change the code that makes use of interface.
Spring is smart. It will find the implementation of the interface and inject it appropriately (or a proxy thereof.)
You should be programming to interfaces, not implementations.