Java使用反射操作对象方法

通过反射机制调用对象中不同修饰符修饰的方法

package test;

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


public class Test {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, NoSuchFieldException, InvocationTargetException, InstantiationException, IllegalAccessException {
        //先获取Person类的Class对象
        Class personClass = Class.forName("test.Person");
        //创建对象
        Object person = personClass.getDeclaredConstructor().newInstance();
        //获取public修饰的方法
        Method hi = personClass.getMethod("hi", String.class);
        hi.invoke(person, "john");

        //调用private修饰的方法
        Method say = personClass.getDeclaredMethod("say", String.class, char.class);
        //私有方法，进行暴破
        say.setAccessible(true);
        //如果有返回值则统一封装为Object，但运行类型与方法返回类型一致
        System.out.println(say.invoke(person, "hello", 'a'));

        //调用静态的private方法
        Method eat = personClass.getDeclaredMethod("eat");
        //私有方法，进行暴破
        eat.setAccessible(true);
        eat.invoke(null); //静态方法可使用null代替对象

    }
}

class Person {
    public void hi(String str) {
        System.out.println("hi," + str);
    }

    private String say(String str, char c) {
        return str + "," + c;
    }

    private static void eat() {
        System.out.println("eat");
    }
}