Introduction to the reflection tool framework in the Java class library

Introduction to the reflection tool framework in the Java class library In Java, the reflection mechanism allows us to dynamically obtain and operate information at runtime, including creating objects, calling methods, access fields, etc.In order to make it easier to use the reflection mechanism, the Java class library provides some powerful reflection tool frameworks to simplify the complexity of the reflex operation. 1. Java.lang.reflect package: The core library of the Java reflection mechanism provides Class, Constructor, Field, and Method, which can be used to obtain information, create objects, and execute methods. The following is a simple example that demonstrates how to use the reflection to create objects and call the method: import java.lang.reflect.Constructor; import java.lang.reflect.Method; public class ReflectionExample { public static void main(String[] args) throws Exception { // Get the class object Class<?> clazz = Class.forName("com.example.MyClass"); // Get the constructor object Constructor<?> constructor = clazz.getConstructor(); // Create objects Object obj = constructor.newInstance(); // Get the method object Method method = clazz.getMethod("myMethod"); // Call method method.invoke(obj); } } 2. ORG.Reflections Library: This library provides a series of extensions and enhanced functions for the reflection mechanism.It uses the method of scanning of class paths to automatically find and manage information, including class, methods, fields and annotations.It can easily achieve scanning and solution function similar to the Spring framework. The following is an example that demonstrates how to scan and obtain a class with specific annotations: import org.reflections.Reflections; public class ReflectionsExample { public static void main(String[] args) { // Create a Reflections object and specify the package name to be scanned Reflections reflections = new Reflections("com.example"); // Get a class with specific annotations Set<Class<?>> annotatedClasses = reflections.getTypesAnnotatedWith(MyAnnotation.class); // Traversing each class for (Class<?> clazz : annotatedClasses) { System.out.println(clazz.getName()); } } } The above is a brief introduction to the two commonly used reflection tool frameworks in the Java class library.These tools can greatly simplify the complexity of using the reflection mechanism, allowing us to more flexibly operate the information and behavior of the class.In actual development, we can choose suitable tool frameworks according to needs, and combine the reflection mechanism to achieve more flexible and powerful functions.