ObjectOutputStream可以将一个内存中的Java对象通过序列化的方式写入到磁盘的文件中。被序列化的对象必须要实现Serialzable序列化接口，否则会抛出异常。

创建对象

public class Users implements Serializable {
    private int userid;
    private String username;
    private String userage;

    public Users(int userid, String username, String userage){
        this.userid = userid;
        this.username = username;
        this.userage = userage;
    }

    public Users(){
    }

    public int getUserid(){
        return userid;
    }

    public void setUserid(int userid){
        this.userid = userid;
    }

    public String getUsername(){
        return username;
    }

    public void setUsername(String username){
        this.username = username;
    }

    public String getUserage(){
        return userage;
    }

    public void setUserage(String userage){
        this.userage = userage;
    }

    @Override
    public String toString(){
        return "Users{" + 
                "userid=" + userid + 
                ", username='" + username + '\'' + 
                ", userage='" + userage + '\'' +
                '}';
    }
}

序列化对象

public class TestObjectOutputStream {
    public static void main(String[] args){
        //创建对象输出字节流与文件输出字节流对象
        try(ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("d:/data3"))){
            //创建Users对象
            Users users = new Users(1,"oldli","18");
            //将对象序列化到文件中
            oos.writeObject(users);
            //刷新
            oos.flush();
        }catch(IOException e){
            e.printStackTrace();
        }
    }
}