C#中StreamReader已定义关闭仍提示文件被其他进程占用问题求助

我是C#新手，对OOP（面向对象编程）和低耦合技术不熟悉。目前遇到问题：我认为已在方法内关闭StreamReader，但仍提示文件被其他进程占用。该StreamReader的Read方法位于ReadandWriteTxtfile类中。

相关核心代码 #

1. MMCM Library_main #

public partial class MMCMLibrary_home : Form
{
    // 实例化背景颜色类
    TimeFrame_Colors TimeFrame = new TimeFrame_Colors();
}

private void frmMainScreen_Load(object sender, EventArgs e)
{
    timerlblClock.Start();
    TimeFrame.Colors();
}
private void frmMainScreen_Load(object sender, EventArgs e)
{
    timerlblClock.Start();
    TimeFrame.Colors();
}

2. ReadandWriteTxtfile #

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Windows.Forms;

namespace MMCM_Library
{
    internal class ReadandWriteTxtfile
    {
        public void Write(string filepath, string process)
        {
            StreamWriter Write = new StreamWriter(Application.StartupPath + "\\Database\\" + "\\DCRTimeFrameColors\\" + filepath);
            Write.WriteLine(process);
            Write.Close();
           
        }
        public string Read(string filepath)
        {
            StreamReader Read = new StreamReader(Application.StartupPath + "\\Database\\" + "\\DCRTimeFrameColors\\" + filepath);
            return Read.ReadLine();
            Read.Close();
        }
    }
}

3. MMCMLibrary_reserve #

namespace MMCM_Library
{
    public partial class MMCMLibrary_reserve : Form
    {
        public static MMCMLibrary_reserve instance;
        int room;

        ReadandWriteTxtfile Writer = new ReadandWriteTxtfile();
        ReadandWriteTxtfile Reader = new ReadandWriteTxtfile();

        public MMCMLibrary_reserve(int roomNumber)
        {
            InitializeComponent();
            room = roomNumber;
            instance = this;
        }
        
        public void btnDCRoomsReserve_Click(object sender, EventArgs e)
        {
            if (rbtn9.Checked)
            {
                if (room == 1)
                {
                    if (Reader.Read("DCR1_9am.txt") == "1") MessageBox.Show("该时段已被占用或已过期");                
                    else Writer.Write("DCR1_9am.txt", "1");                                          
                }

                else if (room == 2)
                {
                    if (Reader.Read("DCR2_9am.txt") == "1") MessageBox.Show("该时段已被占用或已过期");
                    else Writer.Write("DCR2_9am.txt", "1");                   
                }

                else if (room == 3)
                {
                    if (Reader.Read("DCR2_9am.txt") == "1") MessageBox.Show("该时段已被占用或已过期");
                    else Writer.Write("DCR3_9am.txt", "1");                  
                }

                else if (room == 4)
                {
                    if (Reader.Read("DCR4_9am.txt") == "1") MessageBox.Show("该时段已被占用或已过期");
                    else Writer.Write("DCR4_9am.txt", "1");
                }
                
           }
        }
    }
}

4. TimeFrame_Colors #

namespace MMCM_Library
{
    internal class TimeFrame_Colors
    {
        public static TimeFrame_Colors instance;
        ReadandWriteTxtfile Reader = new ReadandWriteTxtfile();

        public void Colors()
        {
            instance = this;

            // DCR 1 时段颜色设置
            if (Reader.Read("DCR1_9am.txt") == "1")
            {
                MMCMLibrary_home.instance.lbl1_1.BackColor = System.Drawing.Color.Red;
            }
            if (Reader.Read("DCR1_11am.txt") == "1")
            {
                MMCMLibrary_home.instance.lbl1_2.BackColor = System.Drawing.Color.Red;
            }
            if (Reader.Read("DCR1_1pm.txt") == "1")
            {
                MMCMLibrary_home.instance.lbl1_3.BackColor = System.Drawing.Color.Red;
            }
            if (Reader.Read("DCR1_3pm.txt") == "1")
            {
                MMCMLibrary_home.instance.lbl1_4.BackColor = System.Drawing.Color.Red;
            }
        }
    }
}

报错截图 #

问题根源 #

你的Read方法里，Read.Close()永远不会执行——因为return Read.ReadLine();语句会直接终止方法，后续代码根本无法运行。这就导致StreamReader一直处于打开状态，文件被进程占用。另外，就算把Close移到return前，若读取过程抛出异常，Close同样不会执行，仍会导致文件占用。

修复步骤 #

1. 用using语句自动释放资源：C#中StreamReader和StreamWriter都实现了IDisposable接口，用using包裹后，代码块结束时会自动调用Dispose方法，关闭流并释放资源，就算出现异常也能保证资源正常释放。

修改后的ReadandWriteTxtfile类：

internal class ReadandWriteTxtfile
{
    // 抽离路径拼接逻辑，避免重复代码
    private string GetFullPath(string filepath)
    {
        return Path.Combine(Application.StartupPath, "Database", "DCRTimeFrameColors", filepath);
    }

    public void Write(string filepath, string process)
    {
        string fullPath = GetFullPath(filepath);
        using (StreamWriter writer = new StreamWriter(fullPath))
        {
            writer.WriteLine(process);
        } // 自动关闭并释放writer
    }

    public string Read(string filepath)
    {
        string fullPath = GetFullPath(filepath);
        using (StreamReader reader = new StreamReader(fullPath))
        {
            return reader.ReadLine();
        } // 自动关闭并释放reader
    }
}

2. 额外优化点：
   • 删除MMCMLibrary_home中重复的frmMainScreen_Load方法，避免编译错误；
   • 修正MMCMLibrary_reserve中room==3时的读取文件错误（当前读的是DCR2_9am.txt，应改为DCR3_9am.txt）。

内容的提问来源于stack exchange，提问作者Javanese Python