会使用条款关闭此流？ [英] Will a using clause close this stream?
问题描述
我显然奏效自己变成一个坏习惯的编码。这是我一直在写代码的例子：
使用（StreamReader的SR =新的StreamReader（File.Open（ somefile.txt，FileMode.Open）））
{
//读取文件
}
File.Move（somefile.txt，somefile.bak）; //不能移动，得到不同的是我的文件被打开
我认为这是因为使用和 子句显式调用关闭（）的Dispose（）上在的StreamReader 的的FileStream 将同时关闭。
我能解决我是有这个问题的唯一途径是通过上面块更改为此：
使用（的FileStream FS = File.Open（somefile.txt，FileMode.Open））
{
使用（StreamReader的SR =新的StreamReader（FS））
{
//读取文件
}
}
File.Move（somefile.txt，somefile.bak）; //可以没有任何错误
应该关闭的StreamReader 在第一块处理也关闭底层的FileStream ？或者，是我错了？
修改
我决定后的代码实际问题的块，就看如果我们能得到这条底线。我只是好奇吧。
我以为我有使用子句中的问题，所以我扩大了所有的东西，它仍然无法复制，每一次。我创建这个方法调用的文件，所以我不认为其他任何对文件打开的句柄。我还证实，从 Path.Combine 调用返回的字符串是正确的。
私有静态无效GenerateFiles（列表<信用与GT;学分）
{
我的账户;
串creditFile = Path.Combine（Settings.CreditLocalPath，DateTime.Now.ToString（MMDDYY-HHMMSS）+.credits）;
的StreamWriter creditsFile =新的StreamWriter（File.Open（creditFile，FileMode.Create））;
creditsFile.WriteLine（code\inc）;
的foreach（在信贷信用C）
{
如果（DataAccessLayer.AccountExists（I））
{
串tpsAuth = DataAccessLayer.GetAuthCode（我。销）;
creditsFile.WriteLine（的String.Format（{0} {1} {\t 2：0.00}，i.AuthCode，i.Pin，c.CreditAmount））;
}
，否则
{
c.Error = TRUE;
c.ErrorMessage =没有户口;
}
DataAccessLayer.AddCredit（C）;
}
creditsFile.Close（）;
creditsFile.Dispose（）;
串DEST = Path.Combine（Settings.CreditArchivePath，Path.GetFileName（creditFile））;
File.Move（creditFile，DEST）;
//File.Delete(errorFile）;
}
是 StreamReader.Dispose 关闭底层流（用于创建一个所有公开的方式）。然而，有一个更好的选择：
使用（TextReader的读者= File.OpenText（file.txt的））
{
}
这有它的提示打开底层流的好处到Windows，你会按顺序访问它。
下面是一个测试应用程序，显示的第一个版本为我工作。我不是说那是什么特别的证据 - 但我很想知道它是如何为你工作。
使用系统;
：使用System.IO;
类节目
{
公共静态无效的主要（字串[] args）
{
的for（int i = 0; I< 1000;我++）
{使用
（StreamReader的SR =新的StreamReader
（File.Open（somefile.txt，FileMode.Open）））
{
控制台。的WriteLine（sr.ReadLine（））;
}
File.Move（somefile.txt，somefile.bak）;
File.Move（somefile.bak，somefile.txt）;
}
}
}
如果这样的作品，它表明它的是与你做什么，而阅读...
而现在这里是你的编辑问题的代码缩短的版本 - 这又正常工作对我来说，即使在网络共享。请注意，我已经改变了 FileMode.Create 到 FileMode.CreateNew - 否则的话能仍一直与旧的文件句柄的应用程序，有可能。 ？这是否对你的工作。
使用系统;
：使用System.IO;
公共类测试
{
静态无效的主要（）
{
的StreamWriter creditsFile =新的StreamWriter（File.Open（test.txt的
FileMode.CreateNew））;
creditsFile.WriteLine（code\\inc）;
creditsFile.Close（）;
creditsFile.Dispose（）;
File.Move（test.txt的，的test2.txt）;
}
}
I've apparently worked myself into a bad coding habit. Here is an example of the code I've been writing:
using(StreamReader sr = new StreamReader(File.Open("somefile.txt", FileMode.Open)))
{
//read file
}
File.Move("somefile.txt", "somefile.bak"); //can't move, get exception that I the file is open
I thought that because the using clause explicitly called Close() and Dispose() on the StreamReader that the FileStream would be closed as well.
The only way I could fix the problem I was having was by changing the above block to this:
using(FileStream fs = File.Open("somefile.txt", FileMode.Open))
{
using(StreamReader sr = new StreamReader(fs))
{
//read file
}
}
File.Move("somefile.txt", "somefile.bak"); // can move file with no errors
Should closing the StreamReader by disposing in the first block also close the underlying FileStream? Or, was I mistaken?
Edit
I decided to post the actual offending block of code, to see if we can get to the bottom of this. I am just curious now.
I thought I had a problem in the using clause, so I expanded everything out, and it still can't copy, every time. I create the file in this method call, so I don't think anything else has a handle open on the file. I've also verified that the strings returned from the Path.Combine calls are correct.
private static void GenerateFiles(List<Credit> credits)
{
Account i;
string creditFile = Path.Combine(Settings.CreditLocalPath, DateTime.Now.ToString("MMddyy-hhmmss") + ".credits");
StreamWriter creditsFile = new StreamWriter(File.Open(creditFile, FileMode.Create));
creditsFile.WriteLine("code\inc");
foreach (Credit c in credits)
{
if (DataAccessLayer.AccountExists(i))
{
string tpsAuth = DataAccessLayer.GetAuthCode(i.Pin);
creditsFile.WriteLine(String.Format("{0}{1}\t{2:0.00}", i.AuthCode, i.Pin, c.CreditAmount));
}
else
{
c.Error = true;
c.ErrorMessage = "NO ACCOUNT";
}
DataAccessLayer.AddCredit(c);
}
creditsFile.Close();
creditsFile.Dispose();
string dest = Path.Combine(Settings.CreditArchivePath, Path.GetFileName(creditFile));
File.Move(creditFile,dest);
//File.Delete(errorFile);
}
Yes, StreamReader.Dispose closes the underlying stream (for all public ways of creating one). However, there's a nicer alternative:
using (TextReader reader = File.OpenText("file.txt"))
{
}
This has the added benefit that it opens the underlying stream with a hint to Windows that you'll be accessing it sequentially.
Here's a test app which shows the first version working for me. I'm not trying to say that's proof of anything in particular - but I'd love to know how well it works for you.
using System;
using System.IO;
class Program
{
public static void Main(string[] args)
{
for (int i=0; i < 1000; i++)
{
using(StreamReader sr = new StreamReader
(File.Open("somefile.txt", FileMode.Open)))
{
Console.WriteLine(sr.ReadLine());
}
File.Move("somefile.txt", "somefile.bak");
File.Move("somefile.bak", "somefile.txt");
}
}
}
If that works, it suggests that it's something to do with what you do while reading...
And now here's a shortened version of your edited question code - which again works fine for me, even on a network share. Note that I've changed FileMode.Create to FileMode.CreateNew - as otherwise there could still have been an app with a handle on the old file, potentially. Does this work for you?
using System;
using System.IO;
public class Test
{
static void Main()
{
StreamWriter creditsFile = new StreamWriter(File.Open("test.txt",
FileMode.CreateNew));
creditsFile.WriteLine("code\\inc");
creditsFile.Close();
creditsFile.Dispose();
File.Move("test.txt", "test2.txt");
}
}
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