c# - 错误 : Help D: System. IO.IOException:进程无法访问该文件，因为它正被另一个进程使用

Question

代码在这里._.

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

    namespace ConsoleApplication1
{
class Program
{

    static void Main(string[] args)
    {
        System.IO.StreamWriter file = new System.IO.StreamWriter("C:\\Users\\Public\\Usernames.txt");
        file.WriteLine();
        file.Close();
        int userType = 0;
        System.IO.StreamReader fileUsername =
            new System.IO.StreamReader("C:\\Users\\Public\\Usernames.txt");
        file.Close();
        string retrievedUsername = fileUsername.ReadToEnd();
        file.Close();



        Console.WriteLine("Please note that this is a prototype, passwords are not hashed/encrypted ^_^");
        Console.WriteLine("Welcome to the meData service! Ver. 0.01 Beta, made by mechron");
        Console.WriteLine("Please enter your username below or type register to register a new account on this device");
        string loginUsername = Console.ReadLine();
      if (loginUsername == retrievedUsername)
   {

          Console.WriteLine("Welcome back user!");
           userType = 1;
   }
      else
      {
          if (loginUsername == "register")
          {

              Console.WriteLine("Choose your username!");
              string registeredUsername = Console.ReadLine();
              System.IO.StreamWriter files = new System.IO.StreamWriter("C:\\Users\\Public\\Usernames.txt");
              file.WriteLine(registeredUsername);
              file.Close();
          }
          else
          {
              Console.WriteLine("Error, command not recognized");}

      }


   }


    }
}

我上面的代码 ^^ Erm...好吧...我遇到了麻烦....System.IO.IOException:进程无法访问该文件，因为它正被另一个进程使用当我点击这条线时不断弹出 System.IO.StreamWriter files = new System.IO.StreamWriter("C:\Users\Public\Usernames.txt");;;有人能帮我吗？提前致谢!

Answer 1

以下代码不会关闭读取器 - 它会再次关闭写入器。即使有效，它也会在您实际阅读之前关闭阅读器。

System.IO.StreamReader fileUsername = new System.IO.StreamReader("C:\\Users\\Public\\Usernames.txt");
file.Close();
string retrievedUsername = fileUsername.ReadToEnd();
file.Close();

你应该让你的代码看起来像这样:

using (System.IO.StreamWriter file = new System.IO.StreamWriter("C:\\Users\\Public\\Usernames.txt"))
{
    file.WriteLine();
}

int userType = 0;
string retrievedUsername = String.Empty;

using (System.IO.StreamReader fileUsername = new System.IO.StreamReader("C:\\Users\\Public\\Usernames.txt"))
{
    retrievedUsername = fileUsername.ReadToEnd();
}

---

下面的代码也有缺陷:

System.IO.StreamWriter files = new System.IO.StreamWriter("C:\\Users\\Public\\Usernames.txt");
file.WriteLine(registeredUsername);
file.Close();

看到错误了吗？您正在打开(而不是关闭!!)一个名为 files 的 StreamWriter，但您正在尝试写入并试图关闭 file。大错。

也可以这样解决:

using (System.IO.StreamWriter files = new System.IO.StreamWriter("C:\\Users\\Public\\Usernames.txt"))
{
    files.WriteLine(registeredUsername);
}