Interpret the working principle and internal implementation of the "Reflections" framework in the Java class library

Reflections is an open source Java class library that is used to obtain and use metada data information that uses the Java class during runtime.It provides a convenient way to find, access and operate, methods, fields, annotations, etc. working principle: The Reflections class library to achieve its functions by using the Java's reflection mechanism.The reflection mechanism allows information to obtain and operate information at runtime, not just compile.Reflections uses this mechanism that users can dynamically obtain and operate various metadata information at runtime. Reflections can achieve its functions through three main components: 1. Scanner: Scanner, for scanning the specified bag or class path, find the class in it, and load them to the memory. 2. MetAdataDapter: Metropolitan adapter to analyze the metadata that has been loaded, and provide access to various elements. 3. Store: memory, used to store metadata information loaded, for subsequent query and use. The workflow of Reflections is as follows: 1. Create a Reflections object and specify the bag or class path to be scanned. 2. Create the Scanner object and associate it with the REFLECTIONS object. 3. Use the Scanner object to scan the specified bag or class path to find and load the class. 4. For each loaded class, use the MetadataAdapter object to analyze its metadata information and store it in the store. 5. Provide a set of APIs that allow users to query the metadata information of loaded classes, such as obtaining all categories, obtaining categories, and obtaining field fields and methods. Reflections internal implementation: Reflections uses Java's reflection mechanism and customized loader to achieve its functions.It uses a custom class loader to load the class under the specified bag or class path, so that these classes can be loaded to the memory for follow -up operations.For each loaded class, Reflections uses Java's reflection mechanism to obtain and operate its metadata information, such as the annotations, fields and methods of the class. Below is a simple example code that demonstrates the basic use of Reflections: // Import Reflections class library import org.reflections.Reflections; public class ReflectionsExample { public static void main(String[] args) { // Create the Reflections object and specify the bag path to scan Reflections reflections = new Reflections("com.example"); // Get all the classes under the specified package trail Set<Class<?>> classes = reflections.getSubTypesOf(Object.class); // Traversing and output the name of each class for (Class<?> clazz : classes) { System.out.println(clazz.getName()); } } } In the above sample code, we created a Reflections object and specified the bag path to scan.Then use the method of `Getsubtypesof ()` to obtain all classes under the specified package path and traverse the name of each class. By using the Reflections class library, we can easily obtain and use meta -data information of Java class during runtime to achieve some advanced functions, such as automated configuration and component scanning.