ASP.NET高效URL重写

public class UrlRouteModule : IHttpModule
{
private static string URL_FLAG = "/q/"; //Url中区别路径和参数的分隔符
private static string URL_SUFFIX = ".aspx"; //对哪种后缀的Url实施Rewrite

public void Init(HttpApplication context)
{
context.BeginRequest += new EventHandler(context_BeginRequest);
}

private void context_BeginRequest(object sender, EventArgs e)
{
HttpApplication app = sender as HttpApplication;
if (app == null) return;

string currentUrl = app.Context.Request.RawUrl;
if (currentUrl.EndsWith(URL_SUFFIX, StringComparison.OrdinalIgnoreCase) == false) //后缀不符合的跳过
return;

int p = currentUrl.IndexOf(URL_FLAG, StringComparison.OrdinalIgnoreCase); //无参的也跳过
if (p == -1) return;

currentUrl = currentUrl.Substring(0, currentUrl.Length - URL_SUFFIX.Length); //去除后缀
string url = string.Format("{0}.aspx", currentUrl.Substring(0, p));
string query = FormmatUrlToQuery(currentUrl.Substring(p + URL_FLAG.Length));

app.Context.RewritePath(url, string.Empty, query);
}

private string FormmatUrlToQuery(string url)
{
int j = 0; //计数器
int len = url.Length;
char[] chars = new char[len];

for (int i = 0; i < len; i++)
{
if (url[i] != '/')
chars[i] = url[i];
else
{
if (++j % 2 == 1)
chars[i] = '=';
else
chars[i] = '&';
}
}

return new string(chars);
}

public void Dispose() { }
}