改寫成可輸入多參數，效能也比較好的版本。
以下為測試碼，請自行依照專案需求做修改。
var root = "C://wdqd/qwewq";
var addPath = @"//\\/fwef/qwf";
var addPath2 = @"5fwfef/qwf";
var addPath3 = @"//fwef/qwf";
var addPath4 = @"\\\fwef/qwf";
var addPath5 = @"\\\\\/fwef/qwf";
var result = root.AddPath(addPath, addPath2, addPath3, addPath4, addPath5);
Console.WriteLine(result);
public static class Helper
{
public static string AddPath(this string value, params string[] addPaths)
{
if (string.IsNullOrEmpty(value))
{
throw new Exception("起始目錄不可以為空字串");
}
if (value.Contains("..") || addPaths.Any(x => x.Contains("..")))
{
throw new Exception($"value: {value}, addPaths: {addPaths.Where(x => x.Contains("..")).ToOneString()} 檔名與路徑不可包含 ..");
}
var paths = addPaths.Select(x => x.Substring(x.FindLastContinuousCharPosition('/', '\\') + 1).SafeFilename()).ToList();
if (paths.Any(x => System.IO.Path.IsPathRooted(x)))
{
throw new Exception("不可併入完整路徑 ..");
}
paths.Insert(0, value.SafeFilename());
return System.IO.Path.Combine(paths.ToArray());
}
public static string ToOneString<T>(this IEnumerable<T> list, string separator = ",")
{
var strList = list.Select(x => x.ToString());
return string.Join(separator, strList);
}
public static int FindLastContinuousCharPosition(this string input, params char[] targets)
{
int lastPosition = -1;
for (int i = 0; i < input.Length; i++)
{
if (targets.Contains(input[i]))
{
lastPosition = i;
}
else
{
break;
}
}
return lastPosition;
}
public static string SafeFilename(this string value)
{
return GetValidFilename(value);
}
public static string GetValidFilename(string value)
{
string ValidFilenameCharacters = @"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\-_$.@:/# ";
if (value.Contains(".."))
{
throw new Exception("路徑中不可包含 .. ");
}
string newUrl = "";
for (int i = 0; i < value.Length; i++)
{
var c = value.Substring(i, 1);
int k = ValidFilenameCharacters.IndexOf(c);
if (k < 0)
{
throw new Exception($"檔名 '{value}' 中有非法的字元 '" + c + "'。");
}
newUrl += ValidFilenameCharacters.Substring(k, 1);
}
return newUrl;
}
}