2.产生原因：

我在创建输出对象流的时候，设置成了可追加状态

       // 创建一个对象输出流
  ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("C:\\ZProject\\Java\\JavaBase\\test\\src\\com\\objectStream\\data.txt",true));

3. 解决方法：

????????把true删掉即可

4. 可执行的源码：

package com.objectStream;

import java.io.*;

public class ObjectOutputStreamExample {
    public static void main(String[] args) throws Exception {
       // 创建一个对象输出流
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream("C:\\ZProject\\Java\\JavaBase\\test\\src\\com\\objectStream\\data.txt"));

        // 创建两个对象
        Student student1 = new Student("张小蓝", "永远的爱", "dushangxilou", 23);
        Student student2 = new Student("李晓清", "消融的雪", "xifengdiaobishu", 15);
        Student student3 = new Student("顾美琪", "寂静的宇宙", "wangjintianyalu", 15);
        Student student4 = new Student("陈佳佳", "温暖的阳关", "denghuolanshanchu", 15);

        // 对象序列化
        objectOutputStream.writeObject(student1);
        objectOutputStream.writeObject(student2);
        objectOutputStream.writeObject(student3);
        objectOutputStream.writeObject(student4);

        // 关闭流文件
        objectOutputStream.close();

        // 创建对象输入流
        FileInputStream fn = new FileInputStream("C:\\ZProject\\Java\\JavaBase\\test\\src\\com\\objectStream\\data.txt");
        ObjectInputStream inputStream = new ObjectInputStream(fn);
        Student s;
        // 判断文件字节流是否大于0，文件中存在内容，小于0表示文件中不存在内容, 循环反序列化每个文件
        while (fn.available() > 0){
            // 将对象反序列化
            s = (Student) inputStream.readObject();
            System.out.println(s );
        }
        // 关闭流文件
        inputStream.close();
        fn.close();
    }
}

package com.objectStream;

import java.io.Serializable;

public class Student implements Serializable {
    private String name;
    private String loginName;
    private String passWord;
    private int age;

    public Student() {
    }

    public Student(String name, String loginName, String passWord, int age) {
        this.name = name;
        this.loginName = loginName;
        this.passWord = passWord;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public String getLoginName() {
        return loginName;
    }

    public void setLoginName(String loginName) {
        this.loginName = loginName;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public int getAge() {
        return age;
    }

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

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