Dagger framework technical guide based on the Java class library
Dagger framework technical guide based on the Java class library
Dagger is a lightweight dependency injection framework built by the Java -class library, which can help developers more conveniently manage and organize the dependencies in the organizational application.This technical guide will introduce how to use the Dagger framework to achieve dependent injection and provide some Java code examples.
1. What is dependent injection?
In software development, dependency relationship refers to an instance that one object (or class) depends on another (or class).Traditional dependencies management methods are manual creation and management object instances. However, this method often leads to redundant and difficult maintenance of code in complex applications.The dependency injection is a more flexible and scalable solution. It gives the object's creation and management to a special framework to deal with it. Developers only need to define the dependency relationship without manual creation and management object instances.
Introduction to Dagger framework
Dagger is a open source dependency injection framework developed by Google. It uses the Java's annotation function to help developers more conveniently achieve dependency injection.The Dagger framework not only provides the function of relying in injection, but also can automatically analyze and manage the dependent relationship between objects in the application.The main features of the Dagger framework include:
1. Lightweight: The Dagger framework has a small impact on the performance and memory consumption of the application, which can be well adapted to applications of various scale.
2. High -efficiency: The Dagger framework can improve the performance and operating efficiency of the application by compiling the code.
3. Scalability: The Dagger framework can easily expand and customize, making it meet the needs of different applications.
3. Use the Dagger framework to achieve dependency injection
1. Define dependency: Before using the Dagger framework, we need to define the dependencies in the application first.Suppose we have a service class that needs to be used in the application:
public class MyService {
public void doSomething() {
// Do something
}
}
2. Declars dependencies: Next, we need to declare the dependency relationship in the application and use the Dagger's annotation to mark these dependencies:
public class MyActivity {
@Inject
MyService myService;
public void onCreate(Bundle savedInstanceState) {
// Dagger will automatically inject us into an instance of MyService into myService
DaggerMyComponent.create().inject(this);
}
}
3. Create a dependent injection component: In the above code, we use Dagger's annotation `@inject` to mark the dependency relationship of` myService`, and use the `daggerMycomPonent.create (). Inject (this)`.To create a dependency injection component and inject dependencies.
4. Configure the Dagger dependencies in the injection module: In the Dagger framework, we can also use the@module `annotation to configure the dependent injection module to help Dagger better manage the instantiated process of objects.For example, we can create an instantiated process of `mymodule` module to configure` myService`:
@Module
public class MyModule {
@Provides
MyService provideMyService() {
return new MyService();
}
}
5. Combination dependency injection module: Next, we need to create an interface or class that rely on the injection module to combine all dependencies:
@Component(modules = {MyModule.class})
public interface MyComponent {
void inject(MyActivity myActivity);
}
Through the above steps, we can use the Dagger framework to achieve dependency injection.When the instance of the `MyActivity` is created, the Dagger framework will automatically inject an instance of the` MyService`.
This article briefly introduces the use of the Dagger framework based on the Java library, and provides some Java code examples.It is hoped that readers can initially understand the basic use of the Dagger framework through this guide, further explore and apply dependency injection technology to optimize and enhance their Java application development experience.
