Learn from the functions and uses of the Java library reflection tool

The functions and uses of the Java library reflection tool Overview: Java is an object -oriented programming language, and the Java class library reflection tool is one of its powerful features.Through the Java -class library reflection tool, we can dynamically load, call class methods and access/modifying fields at runtime.This dynamic enables the Java library reflection tools can be applied to many fields, such as log records, framework development, and code generation. Basic concept of Java reflection: In the normal development process, we usually know the names of the class we want to use during compilation, and operate the object according to the claim's declaration.However, the Java library reflection tool provides the ability to dynamically find and operate the class during runtime.Through the Java reflection, we can obtain the class, methods, and field information of the object at runtime, and can directly call and operate them without having to know the information in advance. Function of Java reflection tools: 1. Obtain class information: Java -class library reflection tool allows us to obtain category information at runtime, such as category, parent class, interface, method and field. 2. Dynamic creation object: Using Java reflection, we can create objects dynamically without the type of objects during compilation.This can help us realize flexible code design and instance. 3. Method of calling objects: With the help of Java reflection, we can dynamically call the object's method, including public methods, private methods, and static methods. 4. Visit and modify field: reflection allows us to obtain and modify the field value of the object, or even private fields. Java reflection tools: 1. Framework development: Java library reflection tools are very useful when achieving some common frameworks.By reflection, the framework can automatically load and call appropriate classes or methods at runtime. 2. Logging: reflex can be used to generate detailed log information.By checking the type and calling method of the object, we can record the detailed information of the class and methods to better debug and analyze the application. 3. Dynamic proxy: reflection enables us to generate proxy objects at runtime, and dynamically handle the calls of real objects.This is very useful in cut -off programming and middleware development. 4. Unit test: reflection can help us access private methods and fields in unit testing, so that we can test the code more comprehensively. Java code example: Below is a simple Java code example, showing how to use the Java class library reflection tool to obtain the information and calling methods of the class. import java.lang.reflect.Method; public class ReflectionExample { public static void main(String[] args) throws Exception { Class <?> Clazz = class.Forname ("com.example.myclass"); // dynamic loading class // Get the class name System.out.println ("" class name: " + Clazz.getName ()); // All public methods to obtain a class Method[] methods = clazz.getMethods(); for (Method method : methods) { System.out.println ("Method name:" + Method.getname ()); } // Create an object and call the method Object obj = clazz.newInstance(); Method method = clazz.getDeclaredMethod("myMethod"); method.invoke(obj); } } class MyClass { public void myMethod() { System.out.println ("The MyMethod Method"); } } In the above example, we use the `class.Forname ()` method to dynamically load the `MyClass` class, and obtain the class name through the` GetName () `method.Then, we use the `GetMethods ()` method to obtain all the public methods of the class and print it on the console.Then, we created an instance of the `myclass` class through the` newInstance () `, and obtained the` mymethod` method with the method of `getDeclaredMeththod ()`.Finally, we used the `Invoke ()` method to call the method and print a message. in conclusion: Through the Java library reflection tool, we can dynamically operate the class, methods, and fields at runtime.The functions and uses of Java reflection are very wide, including framework development, log records, dynamic agents and unit testing.However, it should be noted that excessive use of reflection may reduce performance, so it should be used moderately in practical applications.