反射进行类的获取和相关的字段的获取

Posted 2021-08-07 SmallCuteMonkey

三种方式获取该类的class:

1. 通过包名Class.forName("");
2. 通过Class clazz1=User.class;

3. User u1=new User();
    Class<? extends User> clazz3 = u1.getClass();
   

4. 获取包名 u1.getPackage()
5. 获取类名 u1.getName()

package com.hou.pojo;


//object类本身并没有实现Cloneable这个接口，所以需要我们自己进行实现
public class User  implements Cloneable {
    private Integer id;
    private String username;
    public String password;

   public User(){
       System.out.println("i am a brave boy and i love everyone");


   }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\\'' +
                ", password='" + password + '\\'' +
                '}';
    }


    public User copyObject() throws CloneNotSupportedException {
//        Object clone = this.clone(); 方法一
        Object clone = super.clone();// 方法二
        return (User) clone;


    }

    public static void main(String[] args) throws Exception {
       User user=new User(1,"iamakindandloveboy","111");
        System.out.println(user+"------------");

        User user1 = user.copyObject();

        System.out.println(user1+"*********************");


    }

}

package com.hou.test;

import com.hou.pojo.User;

import java.lang.reflect.Field;

public class TestUser {
    public static void main(String[] args) throws Exception{
        Class clazz1=Class.forName("com.hou.pojo.User");

        Class clazz2=User.class;


        User u1=new User();
        Class<? extends User> clazz3 = u1.getClass();


//        三个方法获取到的类名相同
        System.out.println(clazz1 == clazz2);
        System.out.println(clazz2 == clazz3);


//        字段


   /*     Field[] fields=clazz2.getFields();
        for (Field field:fields
             ) {

            System.out.println(field);

        }
        通过这个不可以获取声明的字段
        */
        Field[] declaredFields = clazz2.getDeclaredFields();
        for (Field field:declaredFields){

            System.out.println(field);
        }
// getFields()方法只可以获取公共的属性，getDeclaredFileds方法可以获取全部的声明的属性

        Field[] fields=clazz2.getFields();
        for (Field field:fields
        ) {

            System.out.println(field);

        }
 Package aPackage = clazz1.getPackage();
        String name = clazz1.getName();
        System.out.println(aPackage);
        System.out.println(name);


    }
}