java反射的基础

import org.w3c.dom.ls.LSOutput;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;

public class MyReflection {
    public static void main(String[] args) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException, NoSuchMethodException, InvocationTargetException, InstantiationException {
        //获取类对象的三种方式
        Class cls = Class.forName("Reflection.Person");
        System.out.println(cls);
        Class personClass = Person.class;
        System.out.println(personClass);
        Person p=new Person();
        Class aClass = p.getClass();
        System.out.println(aClass);
        //获取public修饰的成员变量
        Field[] fields = personClass.getFields();
        Arrays.stream(fields).forEach(s-> System.out.println(s));
        Field a = personClass.getField("a");
        //赋值
        a.set(p,"name");
        System.out.println(a.get(p));
        System.out.println("====================");
        //获取全部权限的成员变量
        Field[] declaredFields = personClass.getDeclaredFields();
        Arrays.stream(declaredFields).forEach(s-> System.out.println(s));
        System.out.println("========================");

        Field name = personClass.getDeclaredField("name");

        //加强反射将private修饰的成员变量进行赋值操作
        name.setAccessible(true);
        name.set(p,"lx");
        System.out.println(name.get(p));
        //获取构造方法
        System.out.println("========================");
        Constructor[] constructors = personClass.getConstructors();
        System.out.println(constructors);
        //获取构造方法
        Constructor constructor = personClass.getConstructor(int.class, String.class);
        //使用构造方法
        System.out.println("====================");
        Object instance = constructor.newInstance(28, "张三");
        System.out.println(instance);
        personClass.newInstance();

//        System.out.println(p);
        System.out.println("=================");
        Method declaredMethod = personClass.getDeclaredMethod("eat");

        declaredMethod.invoke(p);
        Method sleep = personClass.getDeclaredMethod("sleep", String.class);
        sleep.setAccessible(true);
        sleep.invoke(p,"lx");

    }

}``

Person类：

public class Person {
    private int age;
    private String name;
    public String a;
    protected  String b;
    public  String c;
    private String d;

    public int getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

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

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

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

    public Person() {
    }
    public void eat(){
        System.out.println("eat");
    }
    private void sleep(String name){
        System.out.println(name+"睡觉");
    }
    @Override
    public String toString() {
        return "Reflection.MyReflection.Person{" +
                "age=" + age +
                ", name='" + name + '\'' +
                ", a='" + a + '\'' +
                ", b='" + b + '\'' +
                ", c='" + c + '\'' +
                ", d='" + d + '\'' +
                '}';
    }
}