类加载与反射

没写到的地方下次一定补

package com.haojinhui2.fanshe;

public class Animal {
    private String name;
    public int age;

    public Animal() {

    }

    private Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    private void Method() {
        System.out.println("私有方法");
    }

    public void Method2(String name) {
        System.out.println("公开方法" + ", " + name);
    }

    @Override
    public String toString() {
        return "Animal{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

package com.haojinhui2.fanshe;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Test3 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
        // 拿到Animal类的字节码文件对象
        Class<Animal> c = Animal.class;
//        Class<? extends Animal> c2 = new Animal().getClass();
//        Class<?> c3 = Class.forName("com.haojinhui2.fanshe.Animal");
        // class com.haojinhui2.fanshe.Animal

        // 拿到构造器
        Constructor<Animal> con = c.getDeclaredConstructor();
        Animal ani = con.newInstance();
        // Animal{name='null', age=0}
//        Animal ani2 = con.newInstance(String.class, int.class);
        // 不对，下次补

        // 拿到成员变量
        Field name = c.getDeclaredField("name");
        // private java.lang.String com.haojinhui2.fanshe.Animal.name
        Field age = c.getDeclaredField("age");
        // public int com.haojinhui2.fanshe.Animal.age

        // 设置对象属性
        name.setAccessible(true);  // 设置私有属性为可访问
        name.set(ani, "小猫");
        age.set(ani, 6);
        // Animal{name='小猫', age=6}

        // 拿到对象方法
        Method met = c.getDeclaredMethod("Method");
        met.setAccessible(true);  // 私有设为可访问
        met.invoke(ani);
        // 私有方法
        Method method2 = c.getDeclaredMethod("Method2", String.class);
        method2.invoke(ani, "小狗");
        // 公开方法, 小狗
    }
}