Android dependence on the principle and core function analysis of the injection library

Analysis of the principle and core function of Android dependence on the library introduction: With the increase of the complexity of Android applications, the dependency relationship in effective management applications has become more and more critical.Dependent injection is a design pattern that can reduce coupling between code and improve the testability and maintenance of the application.Android dependency injection libraries simplify the development process by automatic parsing and injection dependency relationships. This article will in -depth discussions on the principles and core functions of Android dependencies. 1. What is dependent injection? Dependent injection is a technology that provides the class to the class through an external introduction.It is implemented by entrusting the dependencies required by the class to an external dependent injection container, thereby reducing the direct dependence relationship between categories.Under normal circumstances, dependency injection can inject dependencies by constructing functions, attributes, or method parameters. 2. Android dependence on the principle of injection library The basic principle of Android dependencies is to realize the analysis and injection of dependencies through reflection.It uses annotations to mark classes, fields, and methods, and dynamically analyzes these annotations at runtime, so as to obtain corresponding dependence. As shown below, it is an example of using Android dependencies: public class MainActivity extends AppCompatActivity { @Inject ApiService apiService; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // Create a dependent injection container DaggerAppComponent.builder() .appModule(new AppModule(this)) .build() .inject(this); // Use the injected dependent object apiService.doSomething(); } } In this example, Apiservice is a dependent object that needs to be injected.By adding @inject annotations to the field, the Android dependencies will automatically analyze this annotation and automatically inject the APISERVICE instance when runtime.To use Android dependencies to inject libraries, you need to configure the dependent injecting container in advance, that is, DaggerappComPonent to provide dependent objects when injected. 3. Android dependence on the core function of the injection library 3.1 Injecting dependencies The main function of Android dependencies is to automatically analyze and inject dependencies.It scan the class and its dependencies of @inject comments, instantiated dependent objects through the reflection mechanism, and automatically injected it into the target class. 3.2 Life cycle management Android dependencies can manage the life cycle of dependence on objects.For example, when the dependency object is injected in the oncreate method of the Activity, when the Activity is destroyed, the dependent object is also released to avoid memory leakage. 3.3 Single examples of dependent objects Android dependencies can configure a certain dependent object as a single case, that is, the same dependent object will have only one instance in the life cycle of the entire application.This is particularly useful for objects that are shared global. 3.4 modular configuration Android dependence on the library through the modular configuration can easily manage and organize the dependencies.By defining the module, different dependencies can be classified to improve the readability and maintenance of code. Summarize: Android dependencies in injection libraries simplify the management of complex dependencies in Android applications.It uses the reflex mechanism to automatically analyze and inject dependencies, which improves the testability and maintenance of the code.Through the annotation marker dependency relationship, the dependency injecting library can automatically handle dependencies and achieve better control, management and organization.Use Android dependency injection libraries, developers can quickly develop and maintain high -quality Android applications.