[JAVA] Spring boot memo writing (2)
Purpose
Business efficiency
What is a DI (Dependency injection) container?
** In a nutshell, it translates as "injecting an instance from outside, not a program" ** = "injecting a dependency".
** You can create and use an instance with an external function instead of using the new operator ** to create an instance in your program.
Spring Boot is designed with DI (Dependency Injection), which can reduce ** code dependencies **.
Beans that are instances of the class are stored in the DI container.
Calls between SpringBoot classes are executed by acquiring the beans registered in the DI container.
The standard bean registration method is as follows.
- Add `` `@ Bean``` to the method. The singleton of the class specified in the return value of the method is registered in the DI container.
- Add `` `@ Component``` to the class you want to register as a bean. A singleton of that class is registered in the DI container
- Bean registration of the class is done just by adding
`@ RestController``` which is the API declaration and`@ Configurationt``` which is the environment class declaration.
When SpringBoot starts, the DI container will read the following packages specified by @ComponentScan.
@SpringBootApplication
/* demo.service and demo.Of the domain and below@Annotation for component and DI registration
Classes granted/Register the method in the DI container as a bean.*/
@ComponentScan(
scopedProxy = ScopedProxyMode.TARGET_CLASS,
basePackages = {"demo.service","demo.domain"}
)
public class SBDataBaseDemoApplication {
public static void main(String[] args) {
SpringApplication.run(SBDataBaseDemoApplication.class, args);
}
}
Main annotations for DI
@controllerUsed for controller layer classes.
@restcontrollerUsed for webapi controller layer classes.@controllerWhen@responsebodyIt is a combination of.
@serviceUsed for service layer classes. Mainly used for classes that execute business logic.
@repositoryUsed for data layer classes. Mainly used for classes that access db.
@componentIn addition to the above, it is used for di target classes.
reference
Spring main points
https://atuweb.net/201509_spring_framework_good_points/
RESTful Web Service created with Spring Boot
https://www.slideshare.net/WataruOhno/spring-fest-2018-spring-bootrestful-web-service https://terasolunaorg.github.io/guideline/5.0.1.RELEASE/ja/ArchitectureInDetail/REST.html
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