反射

• 概述
• 获取字节码Class对象的三种方式
• • Fields
  • Constructor
  • Method
  • 获取类名

概述

---

获取字节码Class对象的三种方式

Fields

public class Person {
    public String name;
    public int age;

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

import java.lang.reflect.Field;

public class NewClass {
    public static void main(String[] args) {
        Class<Person> personClass = Person.class;
        Field[] fields = personClass.getFields();
        for (Field field : fields) {
            System.out.println(field);
        }
        Field newField = personClass.getField("name");
        Person per = new Person("小新",6);
        Object o = newField.get(per);
        System.out.println(o);
        newField.set(per,"妮妮");
        System.out.println(per);
    }
}

getDeclaredFields

public class Person {
    private String name;
    public int age;

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

import java.lang.reflect.Field;

public class NewClass {
    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException {
        Class<Person> personClass = Person.class;
        Field[] fields = personClass.getDeclaredFields();
        for (Field field : fields) {
            System.out.println(field);
        }
        Field newField = personClass.getDeclaredField("name");
        newField.setAccessible(true);       //类中有private需要用setAcessible暴力反射
        Person per = new Person("小新",6);
        Object o = newField.get(per);
        System.out.println(o);
        newField.set(per,"妮妮");
        System.out.println(per);
    }
}

Constructor

public class Person {
    public String name;
    public int age;

    public Person() {
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

public class ConClass {
    public static void main(String[] args) throws Exception {
        Class personClass = Person.class;
        Constructor constructor1 = personClass.getConstructor(String.class,int.class);
        Object newPer = constructor1.newInstance("小新", 6);
        System.out.println(newPer);
        Object o = personClass.newInstance();
        System.out.println(o);
    }
}

Method

public class Person {
    public void method(String name) {
        System.out.println("我是方法" + name);
    }
}

import java.lang.reflect.Method;

public class MethodClass {
    public static void main(String[] args) throws Exception {
        Class personClass = Person.class;
        Method method1 = personClass.getMethod("method", String.class);
        Person p1 = new Person();
        method1.invoke(p1,"小新");
    }
}

获取类名

Class personClass = Person.class;
String name = personClass.getName();
System.out.println(name);

标签：name,2021.6,age,30,笔记,class,Person,public,String
来源： https://blog.csdn.net/q4451728/article/details/118361344