Class提供的获取类构造器的方法以及获取类构造器的作用

代码：掌握获取类的构造器，并对其进行操作

Cat类

package com.itheima.day9_reflect;public class Cat {private String name;private int age;private Cat(String name, int age) {this.name = name;this.age = age;System.out.println("有参数构造器执行了~~");}private Cat() {System.out.println("无参数构造器执行了~~");}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Cat{" +"name='" + name + '\'' +", age=" + age +'}';}
}

Test2Constructor类（主程序）

package com.itheima.day9_reflect;import org.junit.Test;import java.lang.reflect.Constructor;/*
* 目标:掌握获取类的构造器，并对其进行操作。
* */
public class Test2Constructor {@Test//获取全部构造器public void testGetConstructors() throws Exception {//1、反射第一步:必须先得到这个类的Class对象Class c = Cat.class;// 2、获取类的全部构造器// Constructor[] constructors = c.getConstructors();Constructor[] constructors = c.getDeclaredConstructors();// 3、遍历数组中的每个构造器对象for (Constructor constructor : constructors) {System.out.println(constructor.getName()+"====>"+constructor.getParameterCount());}}@Testpublic void testGetConstructor() throws Exception {//1、反射第一步:必须先得到这个类的Class对象Class c = Cat.class;// 2、获取某个构造器:无参数构造器//Constructor constructor2 = c.getConstructor();Constructor constructor1 = c.getDeclaredConstructor();System.out.println(constructor1.getName()+"====>"+constructor1.getParameterCount());constructor1.setAccessible(true);//禁止检查访问权限Cat cat = (Cat) constructor1.newInstance();System.out.println(cat);// 3、获取有参数构造器Constructor constructor2 = c.getDeclaredConstructor(String.class, int.class);System.out.println(constructor2.getName()+"====>"+constructor2.getParameterCount());constructor2.setAccessible(true);//禁止检查访问权限Cat cat2 = (Cat) constructor2.newInstance("叮当猫",3);System.out.println(cat2);}
}