MVC 5 和 6 可以选择为您的路由生成小写 URL。我的路线配置如下所示：
public static class RouteConfig
{
public static void RegisterRoutes(RouteCollection routes)
{
// Imprive SEO by stopping duplicate URL's due to case or trailing slashes.
routes.AppendTrailingSlash = true;
routes.LowercaseUrls = true;
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional });
}
}
使用此代码，您应该不再需要规范化 URL，因为这是为您完成的。如果您使用 HTTP 和 HTTPS URL 并为此需要一个规范的 URL，则可能会出现一个问题。在这种情况下，很容易使用上述方法并将 HTTP 替换为 HTTPS，反之亦然。
另一个问题是链接到您网站的外部网站可能会省略尾部斜杠或添加大写字符，为此您应该执行 301 永久重定向到带有尾部斜杠的正确 URL。完整用法和源代码，参考我的博文和RedirectToCanonicalUrlAttribute过滤器：
/// <summary>
/// To improve Search Engine Optimization SEO, there should only be a single URL for each resource. Case
/// differences and/or URL's with/without trailing slashes are treated as different URL's by search engines. This
/// filter redirects all non-canonical URL's based on the settings specified to their canonical equivalent.
/// Note: Non-canonical URL's are not generated by this site template, it is usually external sites which are
/// linking to your site but have changed the URL case or added/removed trailing slashes.
/// (See Google's comments at http://googlewebmastercentral.blogspot.co.uk/2010/04/to-slash-or-not-to-slash.html
/// and Bing's at http://blogs.bing.com/webmaster/2012/01/26/moving-content-think-301-not-relcanonical).
/// </summary>
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, Inherited = true, AllowMultiple = false)]
public class RedirectToCanonicalUrlAttribute : FilterAttribute, IAuthorizationFilter
{
private readonly bool appendTrailingSlash;
private readonly bool lowercaseUrls;
#region Constructors
/// <summary>
/// Initializes a new instance of the <see cref="RedirectToCanonicalUrlAttribute" /> class.
/// </summary>
/// <param name="appendTrailingSlash">If set to <c>true</c> append trailing slashes, otherwise strip trailing
/// slashes.</param>
/// <param name="lowercaseUrls">If set to <c>true</c> lower-case all URL's.</param>
public RedirectToCanonicalUrlAttribute(
bool appendTrailingSlash,
bool lowercaseUrls)
{
this.appendTrailingSlash = appendTrailingSlash;
this.lowercaseUrls = lowercaseUrls;
}
#endregion
#region Public Methods
/// <summary>
/// Determines whether the HTTP request contains a non-canonical URL using <see cref="TryGetCanonicalUrl"/>,
/// if it doesn't calls the <see cref="HandleNonCanonicalRequest"/> method.
/// </summary>
/// <param name="filterContext">An object that encapsulates information that is required in order to use the
/// <see cref="RedirectToCanonicalUrlAttribute"/> attribute.</param>
/// <exception cref="ArgumentNullException">The <paramref name="filterContext"/> parameter is <c>null</c>.</exception>
public virtual void OnAuthorization(AuthorizationContext filterContext)
{
if (filterContext == null)
{
throw new ArgumentNullException("filterContext");
}
if (string.Equals(filterContext.HttpContext.Request.HttpMethod, "GET", StringComparison.Ordinal))
{
string canonicalUrl;
if (!this.TryGetCanonicalUrl(filterContext, out canonicalUrl))
{
this.HandleNonCanonicalRequest(filterContext, canonicalUrl);
}
}
}
#endregion
#region Protected Methods
/// <summary>
/// Determines whether the specified URl is canonical and if it is not, outputs the canonical URL.
/// </summary>
/// <param name="filterContext">An object that encapsulates information that is required in order to use the
/// <see cref="RedirectToCanonicalUrlAttribute" /> attribute.</param>
/// <param name="canonicalUrl">The canonical URL.</param>
/// <returns><c>true</c> if the URL is canonical, otherwise <c>false</c>.</returns>
protected virtual bool TryGetCanonicalUrl(AuthorizationContext filterContext, out string canonicalUrl)
{
bool isCanonical = true;
canonicalUrl = filterContext.HttpContext.Request.Url.ToString();
int queryIndex = canonicalUrl.IndexOf(QueryCharacter);
if (queryIndex == -1)
{
bool hasTrailingSlash = canonicalUrl[canonicalUrl.Length - 1] == SlashCharacter;
if (this.appendTrailingSlash)
{
// Append a trailing slash to the end of the URL.
if (!hasTrailingSlash)
{
canonicalUrl += SlashCharacter;
isCanonical = false;
}
}
else
{
// Trim a trailing slash from the end of the URL.
if (hasTrailingSlash)
{
canonicalUrl = canonicalUrl.TrimEnd(SlashCharacter);
isCanonical = false;
}
}
}
else
{
bool hasTrailingSlash = canonicalUrl[queryIndex - 1] == SlashCharacter;
if (this.appendTrailingSlash)
{
// Append a trailing slash to the end of the URL but before the query string.
if (!hasTrailingSlash)
{
canonicalUrl = canonicalUrl.Insert(queryIndex, SlashCharacter.ToString());
isCanonical = false;
}
}
else
{
// Trim a trailing slash to the end of the URL but before the query string.
if (hasTrailingSlash)
{
canonicalUrl = canonicalUrl.Remove(queryIndex - 1, 1);
isCanonical = false;
}
}
}
if (this.lowercaseUrls)
{
foreach (char character in canonicalUrl)
{
if (char.IsUpper(character))
{
canonicalUrl = canonicalUrl.ToLower();
isCanonical = false;
break;
}
}
}
return isCanonical;
}
/// <summary>
/// Handles HTTP requests for URL's that are not canonical. Performs a 301 Permanent Redirect to the canonical URL.
/// </summary>
/// <param name="filterContext">An object that encapsulates information that is required in order to use the
/// <see cref="RedirectToCanonicalUrlAttribute" /> attribute.</param>
/// <param name="canonicalUrl">The canonical URL.</param>
protected virtual void HandleNonCanonicalRequest(AuthorizationContext filterContext, string canonicalUrl)
{
filterContext.Result = new RedirectResult(canonicalUrl, true);
}
#endregion
}
确保所有请求都被 301 重定向到正确的规范 URL 的使用示例：
filters.Add(new RedirectToCanonicalUrlAttribute(
RouteTable.Routes.AppendTrailingSlash,
RouteTable.Routes.LowercaseUrls));