直接用明文文本的方式保存对象信息不是非常科学，现在用二进制序列化的方式来保存。

这里要先增加命名空间：using System.Runtime.Serialization.Formatters.Binary;，还要给实体类增加序列化标识特性。

通过分层设计来实现：

实体类

Student.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SaveClassInfoToFile
{
    [Serializable]  // 增加序列化特性
    class Student
    {
        public string Name { get; set; }
        public int Age { get; set; }
        public string Gender { get; set; }
        public string Brithday { get; set; }
    }
}

Service

StudentService.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.Serialization.Formatters.Binary;
using System.IO;

namespace SaveClassInfoToFile
{
    class StudentService
    {
        public Student stu;

        // 序列化
        public void SerializeObj()
        {
            // [1]创建文件流
            FileStream fs = new FileStream(@"stuInfo.stu", FileMode.Create);
            // [2]创建二进制格式
            BinaryFormatter binaryFormatter = new BinaryFormatter();
            // [3]调用序列化方法
            binaryFormatter.Serialize(fs, stu);
            // [4]关闭文件流
            fs.Close();
        }
        // 返序列化
        public Student DeserializeObj()
        {
            // 和序列化的步骤类似
            FileStream fs = new FileStream(@"stuInfo.stu", FileMode.Open);
            BinaryFormatter formatter = new BinaryFormatter();
            Student student = formatter.Deserialize(fs) as Student;
            fs.Close();

            return student;
        }
    }
}

界面

Form.cs：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SaveClassInfoToFile
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.StartPosition = FormStartPosition.CenterScreen;
        }
        
        // 序列化保存对象信息
        private void button4_Click(object sender, EventArgs e)
        {
            Student stu = new Student() {
                Name = this.txtName.Text.Trim(),
                Age = int.Parse(this.txtAge.Text.Trim()),
                Gender = this.txtGender.Text.Trim(),
                Brithday = this.txtBrith.Text.Trim()
            };

            StudentService stuService = new StudentService() { stu = stu};
            stuService.SerializeObj();  // 调用序列化方法
        }
        // 返序列化还原对象信息
        private void button3_Click(object sender, EventArgs e)
        {
            StudentService studentService = new StudentService();
            Student stu = studentService.DeserializeObj();

            // 把数据读出来
            this.txtAge.Text = stu.Age.ToString();
            this.txtGender.Text = stu.Gender;
            this.txtName.Text = stu.Name;
            this.txtBrith.Text = stu.Brithday;
        }
    }
}

运行效果

C# 二进制序列化和返序列化保存和读取对象信息