如何判断一个路径是否存在，不存在则创建

[uniteworld]

要asp.net上传文件用，为每个用户组建立一个文件夹，用C#如何判断这个目录是否存在,如果不存在就创建

[wheeler]

Directory.Exists("路径名");

[lovenoerror]

Exists 方法
.NET Framework 类库
Directory..::.Exists
方法 确定给定路径是否引用磁盘上的现有目录。


命名空间： System.IO
程序集： mscorlib（在 mscorlib.dll 中）

示例

// For File.Exists, Directory.Exists
using System;
using System.IO;
using System.Collections;

public class RecursiveFileProcessor
{
public static void Main(string[] args)
{
foreach(string path in args)
{
if(File.Exists(path))
{
// This path is a file
ProcessFile(path);
}
else if(Directory.Exists(path))
{
// This path is a directory
ProcessDirectory(path);
}
else
{
Console.WriteLine("{0} is not a valid file or directory.", path);
}
}
}


// Process all files in the directory passed in, recurse on any directories
// that are found, and process the files they contain.
public static void ProcessDirectory(string targetDirectory)
{
// Process the list of files found in the directory.
string [] fileEntries = Directory.GetFiles(targetDirectory);
foreach(string fileName in fileEntries)
ProcessFile(fileName);

// Recurse into subdirectories of this directory.
string [] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
foreach(string subdirectory in subdirectoryEntries)
ProcessDirectory(subdirectory);
}

// Insert logic for processing found files here.
public static void ProcessFile(string path)
{
Console.WriteLine("Processed file '{0}'.", path);
}
}

[lovenoerror]

补充一下
原文地址:http://technet.microsoft.com/zh-cn/sysinternals/system.io.directory.exists.aspx

经常上去看看微软挺好 经常都会给一些示例代码

[Peter200694013]

Exists 确定给定路径是否引用磁盘上的现有目录。

if (Directory.Exists(path))
{
Console.WriteLine("That path exists already.");
return;
}

// Try to create the directory.
DirectoryInfo di = Directory.CreateDirectory(path);
Console.WriteLine("The directory was created successfully at {0}.", Directory.GetCreationTime(path));

// Delete the directory.
di.Delete();
Console.WriteLine("The directory was deleted successfully.");

[wuyq11]

protected void btnUpload_Click(object sender, EventArgs e)
{
if (fileUpload.HasFile)
{
string savePath = Server.MapPath("~/upload/");
if (!System.IO.Directory.Exists(savePath))
{
System.IO.Directory.CreateDirectory(savePath);
}
savePath = savePath + "\\" + fileUpload.FileName;
fileUpload.SaveAs(savePath);//保存文件
}
}

[meceky]

[Quote=引用 1 楼 asdf311 的回复:]

Directory.Exists("路径名");
[/Quote]
一般用这个方法了。

[poloyzhang]

try
{
// string errorDirectory = @"D:\Program Files\error_salary"; //如果该目录不存在将创建
string errorPath = @"D:\Program Files\error_salary" + "\\" + fileName +".txt";
//start access file
if (!System.IO.File.Exists(errorPath))
{
// Create a file to write to.
using (System.IO.StreamWriter sw = System.IO.File.CreateText(errorPath))
{
sw.WriteLine( exceptionString ); //将导常写入文件.
}
}
else
{
// This text is always added, making the file longer over time
// if it is not deleted.
using (System.IO.StreamWriter sw2 = System.IO.File.AppendText(errorPath))
{
sw2.WriteLine();
// sw.WriteLine(sqlTable);
sw2.WriteLine(DateTime.Now + " ");
sw2.WriteLine( exceptionString );
}
}
//end

}
catch (Exception ec)
{
Console.WriteLine(ec.ToString());
}

[poloyzhang]

    try
            {
               // string errorDirectory = @"D:\Program Files\error_salary";  //如果该目录不存在将创建
                string errorPath = @"D:\Program Files\error_salary"  + "\\" + fileName +".txt";
                                //start access file 
                if (!System.IO.File.Exists(errorPath))
                {
                    // Create a file to write to.
                    using (System.IO.StreamWriter sw = System.IO.File.CreateText(errorPath))
                    {
                        sw.WriteLine( exceptionString ); //将导常写入文件.
                    }
                }
                else
                {
                    // This text is always added, making the file longer over time
                    // if it is not deleted.
                    using (System.IO.StreamWriter sw2 = System.IO.File.AppendText(errorPath))
                    {
                        sw2.WriteLine();
                        // sw.WriteLine(sqlTable);
                        sw2.WriteLine(DateTime.Now + "   ");
                        sw2.WriteLine( exceptionString );
                    }
                }
                //end

            }
            catch (Exception ec)
            {
                Console.WriteLine(ec.ToString());
            }

[Ny-6000]

[Quote=引用 6 楼 meceky 的回复:]
引用 1 楼 asdf311 的回复:

Directory.Exists("路径名");

一般用这个方法了。
[/Quote]

就是么。
这个足够啦。

[tackey86]

楼上所有的都回答的是正确的

System.IO.Directory.Exists("路径名");

就这个