C# FileStream StreamWriter 另一个进程异常答案

【问题标题】：C# FileStream StreamWriter another process exceptionC# FileStream StreamWriter 另一个进程异常
【发布时间】：2023-09-16 15:19:01
【问题描述】：

我正在从DataGridView 写入一个 CSV 文件。当我在这个过程中打开文件时（当任务正在写入文件时）我收到一个错误，因为：

The process cannot access the file 'xyz\filename.csv' because it is being used by another process.

我尝试在每次写入后在 file 和 swOut 上手动调用 Flush() 方法，但我仍然收到错误。

我需要使用FileMode.Append，因为在创建文件后我添加了 n 行。我已经尝试了 FileShare 枚举的每个不同选项，但没有任何效果。

我哪里错了？

我的代码：

using (FileStream file = new FileStream(output_file, FileMode.Append, FileAccess.Write, FileShare.Read))
{
    StreamWriter swOut = new StreamWriter(file);
    swOut.AutoFlush = true;
    if (table.Rows.Count == 2)
    {
        for (int i = 0; i <= table.Columns.Count - 1; i++)
        {
            if (i > 0)
            {
                swOut.Write(",");
            }
            swOut.Write(table.Columns[i].HeaderText);
        }
        swOut.WriteLine();
    }
    swOut.Write(category.Replace(",", " ") + "," + name.Replace(",", " ") + "," + address.Replace(",", " ") + "," + locality.Replace(",", " ") + "," + cap.Replace(",", " ") + "," + tel.Replace(",", " ") + "," + fax.Replace(",", " ") + "," + www.Replace(",", " ") + "," + email_results.Replace(",", " ") + "," + business_url.Replace(",", " ") + "," + map_query.Replace(",", " "));
    swOut.WriteLine();
    file.Close();
    if (stop == true) output_file = "";
}

【问题讨论】：

对不起，作为答案而不是评论发布。在右括号之前显示消息框。它显示了吗？
output_file 也是在哪里声明的。你想通过if (stop == true) output_file = ""; 实现什么stop 声明和设置在哪里？
stop 是一个公共布尔值，当我单击停止 btn 时变为真。但是此时总是假的所以它不能什么都不做。
@Peuczyński 是的，它显示消息框。

标签： c# datagridview filestream streamwriter flush

【解决方案1】：

为什么是file.Close();？

应该是swOut.Close();

已编辑：

或者像这样

'using (FileStream file = new FileStream(output_file, FileMode.Append, FileAccess.Write, FileShare.Read))
using (StreamWriter swOut = new File.AppendText(output_file))
{
    'StreamWriter swOut = new StreamWriter(file);
    swOut.AutoFlush = true;
    if (table.Rows.Count == 2)
    {
        for (int i = 0; i <= table.Columns.Count - 1; i++)
        {
            if (i > 0)
            {
                swOut.Write(",");
            }
            swOut.Write(table.Columns[i].HeaderText);
        }
        swOut.WriteLine();
    }
    swOut.Write(category.Replace(",", " ") + "," + name.Replace(",", " ") + "," + address.Replace(",", " ") + "," + locality.Replace(",", " ") + "," + cap.Replace(",", " ") + "," + tel.Replace(",", " ") + "," + fax.Replace(",", " ") + "," + www.Replace(",", " ") + "," + email_results.Replace(",", " ") + "," + business_url.Replace(",", " ") + "," + map_query.Replace(",", " "));
    swOut.WriteLine();
    swOut.Close();
    if (stop == true) output_file = "";
}

【讨论】：

我刚刚修改了我的代码，就像我上次的回答一样：问题是我每次都在打开和关闭（所以解锁）文件。

【解决方案2】：

确保使用代码中的文档的所有文件流都使用

关闭

      Close();

例子：

    //Create the File
    FileStream FS = new FileStream("C:/Path to document",FileMode.Append,FileAccess.Write);
    //Call the Close Method to Close the file
    FS.Close();

确保所有文件流都已关闭，您将不再收到此错误

【讨论】：

这怎么可能是一个解决方案？ OP 已经使用了using，所以它会被自动处理掉。不是吗？
我已经添加了 swOut.Close();和 file.Close();但没有任何改变
我不是在谈论这段代码，我是说其他文件流代码使用他的项目中的文件
@aquanat 确保整个项目代码中的所有文件流都已关闭，我多次遇到同样的问题，这始终是原因
如果您仅在此代码中使用文件流，那么我想我不知道解决方案

【解决方案3】：

好的，解决办法就到这里。

在我宣布之前

public FileStream file;

在主类中。

然后当它开始向datagridview添加行时，我初始化文件流：

file = new FileStream(output_file, FileMode.Append, FileAccess.Write, FileShare.Read);

然后每次我添加一行时，我也在 csv 中添加一行，代码如下：

 StreamWriter swOut =  new StreamWriter(file);
                        swOut.AutoFlush = true;
                        if (table.Rows.Count == 2)
                        {
                            for (int i = 0; i <= table.Columns.Count - 1; i++)
                            {
                                if (i > 0)
                                {
                                    swOut.Write(",");
                                }
                                swOut.Write(table.Columns[i].HeaderText);
                            }
                            swOut.WriteLine();
                        }
                        swOut.Write(category.Replace(",", " ") + "," + name.Replace(",", " ") + "," + address.Replace(",", " ") + "," + locality.Replace(",", " ") + "," + cap.Replace(",", " ") + "," + tel.Replace(",", " ") + "," + fax.Replace(",", " ") + "," + www.Replace(",", " ") + "," + email_results.Replace(",", " ") + "," + business_url.Replace(",", " ") + "," + map_query.Replace(",", " "));
                        swOut.WriteLine();
                        swOut.Close();
                        file.Close();
                        file = new FileStream(output_file, FileMode.Append, FileAccess.Write, FileShare.Read);
                        //file.Lock(0, file.Length);

因此 FileStream 始终处于打开状态，并且不会像我的原始代码那样每次都关闭。

谢谢！

【讨论】：