C# 使用正则表达式引用一组文件路径
我可以用正则表达式对磁盘进行一次读取,而不是三次读取吗C# 使用正则表达式引用一组文件路径,c#,asp.net,regex,file-io,C#,Asp.net,Regex,File Io,我可以用正则表达式对磁盘进行一次读取,而不是三次读取吗 var path = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images/{0}.png", id)); if (!File.Exists(path)) { path = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images/{0}.jpg", id)); if
var path = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images/{0}.png", id));
if (!File.Exists(path))
{
path = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images/{0}.jpg", id));
if (!File.Exists(path))
{
path = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images/{0}.gif", id));
您可以获取目录位置中所有文件的列表,并使用LINQ查找路径,使用:
根据文件的数量,它可能会产生比您的解决方案更好的结果。假设您不在乎点击哪个:
using System.IO
string imagesPath = HttpContext.Current.Server.MapPath("~/Assets/Images");
string path = null;
foreach (var filePath in Directory.GetFiles(imagesPath, id + ".*"))
{
switch (Path.GetExtension(filePath))
{
case ".png":
case ".jpg":
case ".gif":
path = filePath;
break;
}
}
如果
path
不是null
您就找到了一个。这是对@Oded想法的修改,而不是其他任何东西,但我可能会这样做:
var extensions = new HashSet<string>(StringComparer.OrdinalIgnoreCase)
{ ".png", ".gif", ".jpg", ".bmp" };
var firstMatchingPath = Directory.EnumerateFiles(Server.MapPath("~/Assets/Images/"))
.Where(s => extensions.Contains(Path.GetExtension(s))
.FirstOrDefault();
var extensions=newhashset(StringComparer.OrdinalIgnoreCase)
{.png“,.gif“,.jpg“,.bmp”};
var firstMatchingPath=Directory.EnumerateFiles(Server.MapPath(“~/Assets/Images/”)
.Where(s=>extensions.Contains(Path.GetExtension)
.FirstOrDefault();
尝试类似的方法(仅适用于.NET4及以后版本):
这对你有用吗?它使用正则表达式并保持匹配的优先级
var folderPath = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images"));
var regex = new Regex(string.Format("{0}[.](png|jpg|gif)", id));
var fileInfo = new DirectoryInfo(folderPath)
.GetFiles()
.Where(w => regex.Match(w.Name).Success)
.OrderByDescending(o => o.Extension)
// Taking advantage of png jpg gif is reverse alphabetical order,
// take .OrderByDecending() out if you don't care which one gets found first
.FirstOrDefault();
var path = fileInfo != default(FileInfo) ? fileInfo.FullName : string.Empty;
如果我把它缩小一点(2条语句)
有很多好的答案,但我采用了这种结合了几个方面的方法
var path = Directory.EnumerateFiles(HttpContext.Current.Server.MapPath("~/Assets/Images/"), string.Format("{0}.*", id), SearchOption.TopDirectoryOnly).FirstOrDefault();
switch (Path.GetExtension(path))
{
case ".png":
case ".jpg":
case ".gif":
break;
default:
return;
}
对于这种方法,我会得到“路径中的非法字符”。这会告诉您是否存在其中一个文件,但不会告诉您是哪一个。很明显,OP想要现有文件的路径。您想要这样做的原因是什么?性能?
var folderPath = HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images"));
var regex = new Regex(string.Format("{0}[.](png|jpg|gif)", id));
var fileInfo = new DirectoryInfo(folderPath)
.GetFiles()
.Where(w => regex.Match(w.Name).Success)
.OrderByDescending(o => o.Extension)
// Taking advantage of png jpg gif is reverse alphabetical order,
// take .OrderByDecending() out if you don't care which one gets found first
.FirstOrDefault();
var path = fileInfo != default(FileInfo) ? fileInfo.FullName : string.Empty;
var fileInfo = new DirectoryInfo(HttpContext.Current.Server.MapPath(string.Format("~/Assets/Images")))
.GetFiles()
.Where(w => Regex.Match(w.Name, string.Format("{0}[.](png|jpg|gif)", id)).Success)
.OrderByDescending(o => o.Extension)
.FirstOrDefault();
var path = fileInfo != default(FileInfo) ? fileInfo.FullName : string.Empty;
var path = Directory.EnumerateFiles(HttpContext.Current.Server.MapPath("~/Assets/Images/"), string.Format("{0}.*", id), SearchOption.TopDirectoryOnly).FirstOrDefault();
switch (Path.GetExtension(path))
{
case ".png":
case ".jpg":
case ".gif":
break;
default:
return;
}