Analyze the principle of implementation of resolution in Picocontainer Core framework

Picocontainer Core is a lightweight dependency injection (DI) framework that helps developers to achieve the code that can be solved and tested. Dependent injection is a design mode that is used to decoup the dependencies of the object from the code, and is responsible for injecting the dependent instance into the object by the framework.Picocontainer Core works based on this concept. In Picocontainer Core, the principle of relying on resolution can be summarized as the following steps: 1. Registration component: First, developers need to register the injected components.Registration can be registered by manually calling the API provided by the Picocontainer Core, or using the annotation to register. The following is an example code using API manual registration components: PicoContainer container = new DefaultPicoContainer(); container.addComponent(ServiceA.class); container.addComponent(ServiceB.class); 2. Analysis dependencies: Once the component is registered, Picocontainer will discover dependency relationships according to needs and dynamically analyze them.Picocontainer will determine the dependencies between them by checking the constructor, setter method, and field injection by checking the components. The following is an example code injected by the constructor: public class ServiceA { private final ServiceB serviceB; public ServiceA(ServiceB serviceB) { this.serviceB = serviceB; } } public class ServiceB { } 3. Solution dependencies: Once the dependencies are analyzed, the Picocontainer will be defined according to the registered component, instantiated dependencies, and injected it into the corresponding component. The following is an example code that analyzes and solves dependencies: ServiceA serviceA = container.getComponent(ServiceA.class); serviceA.doSomething(); In the above code, Picocontainer will automatically instantly instance the serviceb and inject instances into the constructor of the servicea. It is worth noting that Picocontainer's dependencies are recursive.This means that if there are other dependencies in Services, Picocontainer will continue to analyze and solve them. To sum up, the principle of dependency analysis of the Picocontainer Core framework is achieved by registering components, analysis dependence, and solving dependencies.It can help developers realize loosening and testability of code, providing a convenient way to manage the dependent relationship between objects.