Reflection mechanism: Java. Lang. Reflect

Basic Features of object-oriented programming: encapsulation, inheritance, and polymorphism. Therefore, the following example uses interfaces, abstract classes, and subclasses.

Animal interface:

package com.taobao.demo;public interface Animal {void eat();void say();}

Abstractanimal abstract class:

package com.taobao.demo;public abstract class AbstractAnimal implements Animal {public String name;private Gender gender;public AbstractAnimal() {}public AbstractAnimal(String name, Gender gender) {this.name = name;this.gender = gender;}@Overridepublic void eat() {System.out.println("eat...");}@Overridepublic void say() {System.out.println("say...");}public String getName() {return name;}public void setName(String name) {this.name = name;}public Gender getGender() {return gender;}public void setGender(Gender gender) {this.gender = gender;}public enum Gender {MALE, FEMALE;}}

Cat class:

Package COM. taobao. demo; public class cat extends actanimal implements animal {// Add a private attribute private color eyecolor to the CAT; Public CAT () {} public CAT (string name, gender, color eyecolor) {super (name, gender); this. eyecolor = eyecolor;} @ overridepublic void eat () {system. out. println ("I like to eat fish. ") ;}@ overridepublic void say () {system. out. println ("Miao... miao... miao... ");} public color geteyecolor () {return eyecolor;} public void seteyecolor (color eyecolor) {This. eyecolor = eyecolor;} public Enum color {white, blue, yellow, black ;}}

Dog class:

Package COM. taobao. demo; public class dog extends actanimal implements animal {// Add a private attribute private int age to the dog; public dog () {} public dog (string name, gender Gender, int age) {super (name, gender); this. age = age ;}@ overridepublic void eat () {system. out. println ("I like to eat bone. ") ;}@ overridepublic void say () {system. out. println ("Wang... wang... wang... ");} public void setage (INT age) {This. age = age ;}public int getage () {return age ;}}

The above classes are basic classes used for experiments. It is also a meaningless class specially written for practice.

Animalfactory class:

package com.taobao.demo.factory;import com.taobao.demo.Animal;public class AnimalFactory {public static Animal getInstance(String className) throws InstantiationException, IllegalAccessException, ClassNotFoundException {return (Animal) Class.forName(className).newInstance();}}

 

Test reflection practices:

Package COM. taobao. demo. reflect; import Java. lang. reflect. constructor; import Java. lang. reflect. field; import Java. lang. reflect. method; import COM. taobao. demo. using actanimal; import COM. taobao. demo. animal; import COM. taobao. demo. CAT; import COM. taobao. demo. factory. animalfactory; public class reflectpractice {public static void main (string [] ARGs) throws exception {// all class objects are class instance classes <?> Clazz1 = Class. forname ("com. Taobao. Demo. Cat"); Class <?> Clazz2 = new CAT (). getclass (); Class <?> Clazz3 = cat. class; // judge whether the above three are of the same class system. out. println (clazz1.equals (clazz2) & clazz1.equals (clazz3); // output class name system. out. println (clazz1.getname (); // obtain the Instance Object cat cat0 = (CAT) clazz1.newinstance (); CAT cat1 = new CAT (); // call the cat class constructor by class. The default constructor is obtained in a strange order. Cat cat2 = (CAT) clazz1.getconstructors () [1]. newinstance ("miaomiao", named actanimal. gender. male, Cat. color. yellow); // obtain the corresponding construc by specifying the parameter type Tor <?> CSR = clazz1.getconstructor (string. class, abstractanimal. gender. class, Cat. color. class); // print the method definition, return value, parameter type, and other system of the constructor. out. println (CSR. togenericstring (); // This constructor constructs the Instance Object cat cat3 = (CAT) CSR. newinstance ("miaomiao", named actanimal. gender. male, Cat. color. yellow); // obtain the parent class and Interface Information class <?> Superclass = clazz2.getsuperclass (); system. Out. println ("parent class name:" + superclass. getname (); Class <?> Clazz4 = Class. forname (clazz2.getsuperclass (). getname (); system. Out. println (clazz4.getname (); Class <?> [] Interfaces = clazz3.getinterfaces (); For (class <?> Interf: interfaces) {system. out. println (interf. getname ();} // obtain the attribute field [] fields = clazz3.getdeclaredfields (); For (field: fields) {system. out. println (field. getname ();} // get the attributes of the parent class. Field [] fields2 = clazz3.getfields (); system. out. println ("parent class attribute" + fields2.length); For (field: fields2) {system. out. println (field);} // obtain the member method [] meths = clazz3.getmethods (); For (method: meths) {system. out. println (method);} // call methods of other classes method = clazz1.getmethod ("say"); CAT catt = (CAT) clazz1.newinstance (); method. invoke (catt); method = clazz1.getmethod ("seteyecolor", Cat. color. class); method. invoke (catt, Cat. color. yellow); system. out. println (catt. geteyecolor (); // The Field field = clazz1.getfield ("name"); field. set (cat0, "xiaomao"); system. out. println (field. get (cat0); // test the factory METHOD Animal animal = animalfactory. getinstance ("com. taobao. demo. cat "); animal. getclass (). newinstance (). say ();}}