Java反序列化

Exception in thread "main" java.io.NotSerializableException: com.founder.sun.Person
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at com.founder.sun.Demo2.main(Demo2.java:29)

package com.founder.sun;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Demo2 {

    /**
     * @throws ClassNotFoundException 
     * 
     */

    public static void main(String[] args) throws IOException, ClassNotFoundException {
        // TODO Auto-generated method stub

        
        Person person = new Person();
        person.setAge("25");
        person.setName("Tom");
        System.out.println(person.getName());
        FileOutputStream file = new FileOutputStream("Person.txt");
        ObjectOutputStream ob = new ObjectOutputStream(file);
        ob.writeObject(person);
        System.out.println("序列化成功！！！");
        ob.close();
        
        System.out.println("进行反序列化！！！");
        FileInputStream file_in = new FileInputStream("Person.txt");
        ObjectInputStream obe = new ObjectInputStream(file_in);
        Person Unknow =(Person)obe.readObject();
        System.out.println(Unknow.getName()  + " is " + Unknow.getAge());
        System.out.println("反序列化成功！！！");
        obe.close();
        
       
        
    }

}
class Person implements Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String name;
    public String age;    
}