反射操作对象以及爆破

发表于 更新于 分类于 ， 阅读次数： Valine：

Cat示范类

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package com.zss.reflact;


/**
 * @author zss
 */
public class Cat {
    public String name="asac";
    private int he=10;
    public int age=0;
    int tall=15;
    public void cry(String name){
        System.out.println("HI"+name);
    }
   public void hello(){
        System.out.println("NIAO");
    }
    @Override
    public String toString() {
        String sex = "娜娜";
        return "Cat{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }

    public Cat(String name, int age, int tall) {
        this.name = name;
        this.age = age;
        this.tall = tall;
    }
    private Cat(String name){
        this.name=name;
    }

    public Cat() {
    }
}

反射创建实例

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package com.zss.reflact;

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

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        Class<?> cla= Class.forName("com.zss.reflact.Cat");
        //通过无参构造器
        Object o=cla.newInstance();
        System.out.println(o);
        //有参构造器
        Constructor<?> constructor=cla.getConstructor(String.class,int.class,int.class);
        constructor.newInstance("java",12,56);
        System.out.println(constructor);

        //通过私有构造器
        Constructor<?> constructor1=cla.getDeclaredConstructor(String.class);
        //进行爆破，造成私有可以调用，使用反射可以访问私有的构造器
        constructor1.setAccessible(true);
        constructor1.newInstance("HAHA");
        System.out.println(constructor1);


    }
}

image-20220321214920927

反射访问类的成员

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package com.zss.reflact;

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

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException {
        Class<?> cla= Class.forName("com.zss.reflact.Cat");
        Object o=cla.newInstance();
        Field name=cla.getField("name");
        //如果name为静态static，则下面的o也可以是null，静态也是对象的
        name.set(o,"lili");
        //通过反射得到真实内容
        System.out.println(name.get(o));


        Field he=cla.getDeclaredField("he");
        //爆破
        he.setAccessible(true);
        System.out.println(he.get(o));




    }
}

image-20220321220059624

反射访问方法

当然私有方法也可以爆破调用，其余用法与成员相同

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package com.zss.reflact;

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

/**
 * @author zss
 */
public class Test {
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException {
        Class<?> cla= Class.forName("com.zss.reflact.Cat");
        Object o=cla.newInstance();
        Method method=cla.getMethod("cry",String.class);
        method.invoke(o,"你好啊啊");

    }
}

image-20220321220535697