记录下JAVA反射用法，应用场景就不提了，这里只提用法

public static void main(String[] args) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, IllegalAccessException, InstantiationException, NoSuchFieldException {

        Class<?> reflectionClass = Reflection.class;
        Constructor c = reflectionClass.getConstructor(null);
        Object r= c.newInstance();//构造器实例

        Constructor c2 = reflectionClass.getConstructor(String.class);
        c2.newInstance("hello");

        Constructor c3 = reflectionClass.getConstructor(String.class,int.class);
        c3.newInstance("小明",13);


        System.out.println();
        //通过反射获取实例的方法
        Method method1=reflectionClass.getMethod("getName");        //获取共有getName方法
        Method method2=reflectionClass.getMethod("getAge");         //获取共有getAge方法
        Method method3=reflectionClass.getDeclaredMethod("setName",String.class);  //获取私有setName方法 参数String
        Method method4=reflectionClass.getDeclaredMethod("setAge",int.class);         //获取私有setAge方法 参数String


        method3.setAccessible(true);        //设置操作权限
        method4.setAccessible(true);        //设置操作权限

        method3.invoke(r,"小明");     //调用setName()
        method4.invoke(r,14);          //调用setAge()

        System.out.println(method1.invoke(r));      //调用getName()
        System.out.println(method2.invoke(r));      //调用getAge()


        Field field =reflectionClass.getField("name");         //获取共有字段name
        Field field2=reflectionClass.getDeclaredField("age");//获取私有字段age
        field2.setAccessible(true);         //设置私有字段可访问

        System.out.println("\n============================修改前Feild的值=================================");
        System.out.println(field.getName()+":"+field.get(r)+"\t访问权限："+field.getModifiers()+"\t"+field.getType());
        System.out.println(field2.getName()+":"+field2.get(r)+"\t访问权限："+field2.getModifiers()+"\t"+field2.getType());

        field.set(r,"小米");      //修改name字段的值
        field2.set(r,15);          //修改age字段的值
        System.out.println("\n============================修改后Feild的值=================================");
        System.out.println(field.getName()+":"+field.get(r)+"\t访问权限："+field.getModifiers()+"\t"+field.getType());
        System.out.println(field2.getName()+":"+field2.get(r)+"\t访问权限："+field2.getModifiers()+"\t"+field2.getType());

    }

Reflection.java

public class Reflection {

    public String name;
    private int age;

    public Reflection() {
        System.out.println("无参构造器");
    }

    public Reflection(String a) {
        System.out.println("有参构造器:" + a);
    }


    public Reflection(String name, int age) {
        System.out.println("多参构造器：" + name + "\t" + age);
    }


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

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

}

运行结果：