13 动态创建对象执行方法

反射的作用

package annotate;


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

// 通过反射，动态创建对象
public class Test12 {
    public static void main(String[] args) throws Exception {
        Class c1 = Body.class;
        // 1
        Body body = (Body) c1.newInstance();  // 实际上调用类的无参构造
        System.out.println(body);
        // 2 通过构造器创建对象
        Constructor constructor=c1.getConstructor(int.class,int.class,String.class);
        Body body1= (Body) constructor.newInstance(18,1,"zhan");
        System.out.println(body1);
        System.out.println(body1.getAge());
           // 通过反射操作私有属性
       // body1.age=20;  因为private，不能直接操作
        Field age= c1.getDeclaredField("age");
        age.setAccessible(true);  // 设置为可操作
        age.set(body1,20);
        System.out.println(body1.getAge());
    }
}

class Body{
    private int age;
    private int id;
    private String name;

    public Body(){}
    public Body(int age, int id, String name) {
        this.age = age;
        this.id = id;
        this.name = name;
    }

    public int getAge(){
        return age;
    }
    public void setAge(int age){
        this.age=age;
    }
    public void say(){}
}