Java反射

Posted 2022-05-04 starstarstar

Java的反射：

Robot.java:

package 包.reflect;

public class Robot 
    private String name;

    public void sayHi(String helloSen) 
        System.out.println(helloSen + ":" + name);
    

    private String throwHello(String tag) 
        return "private Hello：" + tag;
    

 ReflectDemo.java:

package 包.reflect;

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

public class ReflectDemo 
    public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InstantiationException, InvocationTargetException, NoSuchFieldException 
        Class rc = Class.forName("包.reflect.Robot");
        Robot r = (Robot) rc.newInstance();
        System.out.println("class name is :" + rc.getName());
        // 获取声明的方法
        // getDeclaredMethod获取不到：继承的方法和实现接口的方法
        Method getPrivateHello = rc.getDeclaredMethod("throwHello", String.class);
        getPrivateHello.setAccessible(true);
        Object str = getPrivateHello.invoke(r, "bob");
        System.out.println("getHello result is :" + str);
        // getMethod获取 类自己的public方法，集成类的方法和实现接口的方法
        Method sayHi = rc.getMethod("sayHi", String.class);
        sayHi.invoke(r, "welcome");
        // 设置name
        Field name = rc.getDeclaredField("name");
        name.setAccessible(true);
        name.set(r, "Alace");
        sayHi.invoke(r, "welcome");

    

 运行结果：

class name is :qihoo.qtest.mqtt.reflect.Robot
getHello result is :private Hello：bob
welcome:null
welcome:Alace