怪我没说清，这个long是这么定义的：

private static final long serialVersionUID = 1L;

直接定义long没用

package com.imooc.file;

import java.io.Serializable;

public class Student implements Serializable {

private String stuno;

private String stuname;

private int stuage;

long serialVersionUID = 1L;

public Student(){

}

public Student(String stuno, String stuname, int stuage) {

super();

this.stuno = stuno;

this.stuname = stuname;

this.stuage = stuage;

}

public String getStuno() {

return stuno;

}

public void setStuno(String stuno) {

this.stuno = stuno;

}

public String getStuname() {

return stuname;

}

public void setStuname(String stuname) {

this.stuname = stuname;

}

public int getStuage() {

return stuage;

}

public void setStuage(int stuage) {

this.stuage = stuage;

}

@Override

public String toString() {

return 

"Student [stuno=" + stuno + ", stuname=" + stuname + ", stuage=" + stuage + "]";

}

}

package com.imooc.file;

import java.io.FileInputStream;

import java.io.ObjectInputStream;

import java.util.ArrayList;

public class ObjectSerialDemo {

public static void main(String[] args)throws Exception{

String file = "demo/obj.dat";

//1、对象的序列化注意student类要实现serializable接口

/*ObjectOutputStream oos = 

new ObjectOutputStream(new FileOutputStream(file));

Student stu = new Student("10001","张三",20);

oos.writeObject(stu);

oos.flush();

oos.close();*/

//反序列化

ObjectInputStream ois = new 

ObjectInputStream(new FileInputStream(file));

Student stu = (Student)ois.readObject();

System.out.print(stu);

ois.close();

}

}