C# Path类常用方法

Path 类

　　对包含文件或目录路径信息的 String 实例执行操作。

　　1.Path.GetExtension 方法 —— 返回指定的路径字符串的扩展名。

　　public static string GetExtension(string path)

string fileName = @"C:\mydir.old\myfile.ext";
string path = @"C:\mydir.old\";
string extension;

extension = Path.GetExtension(fileName);
Console.WriteLine("GetExtension('{0}') returns '{1}'",
    fileName, extension);

extension = Path.GetExtension(path);
Console.WriteLine("GetExtension('{0}') returns '{1}'",
    path, extension);

// This code produces output similar to the following:
//
// GetExtension('C:\mydir.old\myfile.ext') returns '.ext'
// GetExtension('C:\mydir.old\') returns ''

　　2.Path.GetFileName 方法 —— 返回指定路径字符串的文件名和扩展名。

　　public static string GetFileName(string path)

string fileName = @"C:\mydir\myfile.ext";
string path = @"C:\mydir\";
string result;

result = Path.GetFileName(fileName);
Console.WriteLine("GetFileName('{0}') returns '{1}'",
    fileName, result);

result = Path.GetFileName(path);
Console.WriteLine("GetFileName('{0}') returns '{1}'",
    path, result);

// This code produces output similar to the following:
//
// GetFileName('C:\mydir\myfile.ext') returns 'myfile.ext'
// GetFileName('C:\mydir\') returns ''

　　3.Path.GetFullPath 方法 —— 返回指定相对路径字符串的绝对路径.

　　　　public static string GetFullPath(string path)

string fileName = "myfile.ext";
string path1 = @"mydir";
string path2 = @"\mydir";
string fullPath;

fullPath = Path.GetFullPath(path1);
Console.WriteLine("GetFullPath('{0}') returns '{1}'",
    path1, fullPath);

fullPath = Path.GetFullPath(fileName);
Console.WriteLine("GetFullPath('{0}') returns '{1}'",
    fileName, fullPath);

fullPath = Path.GetFullPath(path2);
Console.WriteLine("GetFullPath('{0}') returns '{1}'",
    path2, fullPath);

// Output is based on your current directory, except
// in the last case, where it is based on the root drive
// GetFullPath('mydir') returns 'C:\temp\Demo\mydir'
// GetFullPath('myfile.ext') returns 'C:\temp\Demo\myfile.ext'
// GetFullPath('\mydir') returns 'C:\mydir'

　　4.1 Path.GetTempPath 方法 —— 返回当前用户的临时文件夹的路径。

　　　　string tempPath = Path.GetTempPath（）;

　　4.2 Path.GetRandomFileName 方法 —— 返回随机文件夹名或文件名。

　　　　public static string GetRandomFileName();

　　4.3 Path.GetDirectoryName 方法 —— 返回指定路径字符串的目录信息。

　　　　public static string GetDirectoryName(string path)

　　　　

string filePath = @"C:\MyDir\MySubDir\myfile.ext";
string directoryName;
int i = ;

while (filePath != null)
{
    directoryName = Path.GetDirectoryName(filePath);
    Console.WriteLine("GetDirectoryName('{0}') returns '{1}'",
        filePath, directoryName);
    filePath = directoryName;
    if (i == )
    {
        filePath = directoryName + @"\";  // this will preserve the previous path
    }
    i++;
}
/*
This code produces the following output:

GetDirectoryName('C:\MyDir\MySubDir\myfile.ext') returns 'C:\MyDir\MySubDir'
GetDirectoryName('C:\MyDir\MySubDir') returns 'C:\MyDir'
GetDirectoryName('C:\MyDir\') returns 'C:\MyDir'
GetDirectoryName('C:\MyDir') returns 'C:\'
GetDirectoryName('C:\') returns ''
*/

　　5.Path.ChangeExtension 方法 —— 更改路径字符串的扩展名。

　　public static string ChangeExtension(string path,string extension)

using System;
using System.IO;

public class PathSnippets
{

    public void ChangeExtension()
    {
        string goodFileName = @"C:\mydir\myfile.com.extension";
        string badFileName = @"C:\mydir\";
        string result;

        result = Path.ChangeExtension(goodFileName, ".old");
        Console.WriteLine("ChangeExtension({0}, '.old') returns '{1}'",
            goodFileName, result); 

        result = Path.ChangeExtension(goodFileName, "");
        Console.WriteLine("ChangeExtension({0}, '') returns '{1}'",
            goodFileName, result); 

        result = Path.ChangeExtension(badFileName, ".old");
        Console.WriteLine("ChangeExtension({0}, '.old') returns '{1}'",
            badFileName, result); 

        // This code produces output similar to the following:
        //
        // ChangeExtension(C:\mydir\myfile.com.extension, '.old') returns 'C:\mydir\myfile.com.old'
        // ChangeExtension(C:\mydir\myfile.com.extension, '') returns 'C:\mydir\myfile.com.'
        // ChangeExtension(C:\mydir\, '.old') returns 'C:\mydir\.old'

　　6. Path.Combine 方法 —— 将2-4个字符串组合成一个路径。

　　public static string Combine(string path1,string path2,*string path3,*string path2)

using System;
using System.IO;

public class ChangeExtensionTest {

    public static void Main() {

        string path1 = "c:\\temp";
        string path2 = "subdir\\file.txt";
        string path3 = "c:\\temp.txt";
        string path4 = "c:^*&)(_=@#'\\^&#2.*(.txt";
        string path5 = "";
        string path6 = null;

        CombinePaths(path1, path2);
        CombinePaths(path1, path3);
        CombinePaths(path3, path2);
        CombinePaths(path4, path2);
        CombinePaths(path5, path2);
        CombinePaths(path6, path2);
    }

    private static void CombinePaths(string p1, string p2) {

        try {
            string combination = Path.Combine(p1, p2);

            Console.WriteLine("When you combine '{0}' and '{1}', the result is: {2}'{3}'",
                        p1, p2, Environment.NewLine, combination);
        } catch (Exception e) {
            if (p1 == null)
                p1 = "null";
            if (p2 == null)
                p2 = "null";
            Console.WriteLine("You cannot combine '{0}' and '{1}' because: {2}{3}",
                        p1, p2, Environment.NewLine, e.Message);
        }

        Console.WriteLine();
    }
}
// This code produces output similar to the following:
//
// When you combine 'c:\temp' and 'subdir\file.txt', the result is:
// 'c:\temp\subdir\file.txt'
//
// When you combine 'c:\temp' and 'c:\temp.txt', the result is:
// 'c:\temp.txt'
//
// When you combine 'c:\temp.txt' and 'subdir\file.txt', the result is:
// 'c:\temp.txt\subdir\file.txt'
//
// When you combine 'c:^*&)(_=@#'\^&#2.*(.txt' and 'subdir\file.txt', the result is:
// 'c:^*&)(_=@#'\^&#2.*(.txt\subdir\file.txt'
//
// When you combine '' and 'subdir\file.txt', the result is:
// 'subdir\file.txt'
//
// You cannot combine '' and 'subdir\file.txt' because:
// Value cannot be null.
// Parameter name: path1