The technical principles of the HILT Android framework in the Java class library

The research principles of technical principles in the HILT Android framework in the Java library Introduction: With the rapid development of Android development, the construction of maintenance and scalable code becomes more and more important.Dagger is a popular dependency injection framework, which provides a way to manage dependencies in Android applications.However, using Dagger needs to write a large amount of model code.To simplify this process, Google has launched the HILT framework, which is the expansion of Dagger, designed for the development of Android applications.This article will explore the technical principles of the Hilt framework in the Java class library. 1. What is the HILT framework? The HILT framework is a dependent injection framework supported by Google, which is built on Dagger and optimized the Android application.HILT provides an automatic way to inject the dependency item into the Android class, thereby simplifying the writing and testing of the code. Second, the main component of the HILT framework The HILT framework contains the following main components: 1. HILT Note: The Hilt framework is simplified to simplify the process of dependencies through a series of annotations, such as @AndroidERYPoint, @hiltViewModel, etc. 2. Components: The components in HILT are similar to components in Dagger, which are used to create and provide dependencies.The Hilt framework introduces some new components, such as ApplicationComponent, ActivityComponent, FragmentComponent, etc., which correspond to the global, activity and fragments of the Android applications. 3. Module: The module is an optional part in HILT, defined by @Module annotation.Modules are used to provide or bind dependencies in order to use in components. 4. Scope: The Hilt framework introduces some new scope annotations, such as@Singleton,@ActivityScoped,@Fragmentscope, etc., which are used to mark the life cycle of modules or dependencies. Third, the technical principle of the HILT framework The technical principles of the HILT framework can be summarized as the following key steps: 1. Annotation processor: The HILT framework uses the annotation processor to analyze and process the annotations in the code.When compiling, the annotation processor scan the code in the project and generate the corresponding class and code according to the annotation. 2. Generate code: During the annotation process, the HILT framework will generate many auxiliary classes and code to achieve dependency injection logic.These codes include components, factory classes, and injection logic. 3. Dependent injection: The HILT framework achieves dependency injection logic by generating the generated code.When the object is created, the HILT framework will automatically find and provide dependencies and inject it into the target object. 4. Activity Domain Management: The HILT framework manages the life cycle of components and dependencies through the scope annotation.Components and dependencies using the same scope annotation will be summarized within the scope of the same life cycle to ensure the uniqueness and consistency of dependency relationship within this range. 5. Component relationship: The HILT framework is transmitted and shared by dependent relationships by defining the relationship between components.For example, ActivityComponent can rely on ApplicationComponent to obtain global singles objects. Fourth, the example code of the HILT framework Here are several example code fragments that use the HILT framework: 1. Activity with @AnDroidRypoint: @AndroidEntryPoint public class MainActivity extends AppCompatActivity { @Inject MyDependency myDependency; // ... } In this example,@AndroidERYPOINT Note tells that the Hilt framework regards the Activity as an entry point that depends on the injection, and automatically injected the MyDependency object. 2. Use the viewmodel annotated by @HILTVIEWMODEL: @HiltViewModel public class MyViewModel extends ViewModel { @Inject MyDependency myDependency; // ... } In this example,@hiltViewModel notes tell the HILT framework to regard the ViewModel as an entry point that depends on the injection, and automatically injects the MyDependency object. 3. Provide dependencies in the module: @Module @InstallIn(ApplicationComponent.class) public class MyModule { @Provides @Singleton MyDependency provideMyDependency() { return new MyDependency(); } // ... } In this example, the@module annotation tells that the HILT framework is the module, and the@Installin annotation specifies that the module takes effect in the ApplicationComponent.@Provides annotation indicates that the method is used to provide dependencies, and@Singleton annotation indicates that the dependencies provided as a single object. Summarize: The HILT framework is built on the Dagger and makes full use of the commentary processor's ability to simplify the dependency injection process in Android applications.This article introduces the technical principle of the HILT framework and provides example code, hoping to help understanding and using the HILT framework.