Analysis
Analysis
introduction:
ScalDi is a lightweight dependencies injection framework, which aims to help Java developers manage the dependence between categories in a simple and easy -to -use way.This article will introduce the technical principles of the ScalDi framework and provide some Java code examples to help readers understand.
1 Overview
The core principle of Scaldi is to use dependency injection to decouple the strong connection between the decoupled class.By dependent injection, we can decouple the creation and use by entrusting the dependency to third parties.In ScalDi, all dependencies are defined by binding.
2. Binding
Binding is the core concept in ScalDi, which is used to define the dependency relationship between classes and classes.In SCALDI, the binding is achieved through the inheritance of the Module class.Module defines a set of binding rules that can be used in applications.The following is a simple example:
import scaldi.Module;
public class MyModule extends Module {
public void init() {
bind(EmailService.class).to(EmailServiceImpl.class);
bind(UserRepository.class).to(UserRepositoryImpl.class);
}
}
In the above example, we define the binding relationship between EmailService and UserRepository.When we use EmailService, ScalDi will automatically create an instance of an EmailServiceImpl and inject it into EmailService.
3. Analysis and injection
Once the binding relationship is defined, we can use the RESOLVER class to analyze and inject dependencies.RESOLVER is one of the core categories in ScalDi, which is responsible for creating and analyzing the binding relationship.
Below is an example of using RESOLVER:
import scaldi.Injector;
import scaldi.Module;
import scaldi.Injectable;
import javax.inject.Inject;
public class MyApp implements Injectable {
@Inject
private EmailService emailService;
public void sendEmail() {
emailService.send("hello@example.com", "Hello Scaldi!");
}
public static void main(String[] args) {
Module module = new MyModule();
Injector injector = Injector.apply(module);
MyApp app = injector.instanceOf(MyApp.class);
app.sendEmail();
}
}
In the above example, we created a MyApp class and injected an EmailService instance.Use @inject annotation to inject emailService into MyApp.
4. Life cycle management
ScalDi also supports life cycle management, performing some additional logic when creating and destroying objects.We can add a life cycle management code by covering the BindLifecycle method covering the Module class.The following is an example:
import scaldi.Module;
import scaldi.LifecycleManager;
import javax.inject.Inject;
public class MyModule extends Module {
@Override
public void init() {
bind(EmailService.class).to(EmailServiceImpl.class).withLifecycle(new LifecycleManager() {
@Override
public void init(EmailService emailService) {
EmailService.connect (); // execute initialization logic when creating an EmailService instance
}
@Override
public void destroy(EmailService emailService) {
EmailService.disconnect (); // execute the cleansing logic when destroying the EmailService instance
}
});
}
}
In the above example, we define the creation and destruction logic of EmailService by covering the BindLifecycle method.When creating an EmailService instance, the Connect method is called to initialize, and the disconnect method is called when destroyed.
in conclusion:
This article introduces the technical principles of the ScalDi framework and provides some Java code examples to help readers understand.By using ScalDi, developers can simplify the dependent relationship management between classes and categories to improve the maintenance and testability of code.SCALDI's design concept is lightweight and ease of use, suitable for Java applications of various scale.
