韩顺平Java41——反射Homework

1.

 

 

package com.recorder.ref;

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

/**
 * @author 紫英
 * @version 1.0
 * @discription 反射爆破修改属性
 */
public class Homework01 {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
        Class<?> clazz = Class.forName("com.recorder.ref.PrivateTest");
        Object o = clazz.newInstance();
//        得到name属性的对象
        Field name = clazz.getDeclaredField("name");//因为name是private的
        name.setAccessible(true);
//        得到getName方法的对象
        Method getName = clazz.getMethod("getName");
        name.set(o,"剋踢猫");
        System.out.println(getName.invoke(o));
    }
}
class PrivateTest{
    private String name = "HelloKitty!";

    public String getName() {
        return name;
    }
}

2.

 

 

package com.recorder.ref;

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

/**
 * @author 紫英
 * @version 1.0
 * @discription 反射创建文件
 */
public class Homewor02 {
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        Class<?> fileClass = Class.forName("java.io.File");
        String filePath = "e:\\123.txt";
        //取得有参构造器
        Constructor<?> constructor = fileClass.getConstructor(String.class);
//        通过构造器创建file对象
        Object o = constructor.newInstance(filePath);
        Constructor<?>[] declaredConstructors = fileClass.getDeclaredConstructors();
        for (Constructor<?> declaredConstructor : declaredConstructors) {
            System.out.println(declaredConstructor);
        }
//        取得方法对象
        Method createNewFile = fileClass.getMethod("createNewFile");
//        调用方法创建文件
        createNewFile.invoke(o);


    }
}