如何在ASP中将短URL重定向/重写至原始长URL？

Hey there, I’ve worked through similar URL rewrite headaches for ASP.NET-based link shorteners before, so let’s break down how to get your shrtn.aspx handling those short links properly.

First: Make Sure the URL Rewrite Module is Installed #

This is such a common gotcha—if IIS doesn’t have the URL Rewrite Module enabled, none of your rewrite rules will work at all. Check this in IIS Manager: look for "URL Rewrite" in the server/site features list. If it’s missing, install it via the IIS Web Platform Installer.

Correct Web.config Rewrite Rule #

Your goal is to route any short URL like http://localhost:9909/snKcxi to shrtn.aspx?key=snKcxi. Here’s a tested rule set to add to your web.config under the <system.webServer> section:

<rewrite>
  <rules>
    <!-- Skip actual files/directories to avoid breaking static content -->
    <rule name="Skip Existing Resources" stopProcessing="true">
      <match url=".*" />
      <conditions>
        <add input="{REQUEST_FILENAME}" matchType="IsFile" />
        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" />
      </conditions>
      <action type="None" />
    </rule>

    <!-- Rewrite short links to shrtn.aspx with the key parameter -->
    <rule name="Short Link Rewrite" stopProcessing="true">
      <match url="^([a-zA-Z0-9]+)$" />
      <action type="Rewrite" url="shrtn.aspx?key={R:1}" />
    </rule>
  </rules>
</rewrite>

What this does: #

• The first rule ensures requests for real files (like CSS/JS) or directories aren’t rewritten—so your static content still works.
• The second rule matches any URL path that’s just a string of letters/numbers (your short key), then rewrites it to shrtn.aspx with the key passed as a query string parameter.

Update shrtn.aspx Logic #

Make sure your code correctly pulls the key and handles the redirect (and edge cases):

protected void Page_Load(object sender, EventArgs e)
{
    string shortKey = Request.QueryString["key"];

    // Handle empty or invalid key requests
    if (string.IsNullOrEmpty(shortKey))
    {
        Response.StatusCode = 404;
        Response.Write("Invalid short link.");
        Response.End();
        return;
    }

    // Query your database for the original URL
    string originalUrl = FetchOriginalUrlFromDB(shortKey);

    if (!string.IsNullOrEmpty(originalUrl))
    {
        // Use 301 redirect for SEO (permanent), or 302 if links might change later
        Response.RedirectPermanent(originalUrl, true);
    }
    else
    {
        // Key not found in database
        Response.StatusCode = 404;
        Response.Write("Short link not found.");
        Response.End();
    }
}

// Replace this with your actual database lookup method
private string FetchOriginalUrlFromDB(string key)
{
    using (var conn = new SqlConnection("YourDatabaseConnectionString"))
    {
        conn.Open();
        var cmd = new SqlCommand("SELECT OriginalUrl FROM ShortLinks WHERE ShortKey = @Key", conn);
        cmd.Parameters.AddWithValue("@Key", key);
        return cmd.ExecuteScalar()?.ToString();
    }
}

Extra Checks to Fix 404s #

• Verify IIS Site Path: Double-check that your site’s physical path points to the folder where shrtn.aspx lives.
• Disable Friendly Errors: Temporarily turn off IIS’s "Friendly HTTP Errors" to see a more detailed error message that might pinpoint the issue.
• Test the Regex: Use the URL Rewrite Module’s "Test Pattern" tool in IIS Manager to confirm your short key (like snKcxi) matches the rule’s regex.
• Check for Conflicting Rules: If you have other rewrite rules in web.config, make sure they don’t override this one—the stopProcessing="true" attribute helps prevent that.

Once you implement these changes, test your short link again—you should no longer get a 404, and shrtn.aspx will handle the redirect smoothly.

内容的提问来源于stack exchange，提问作者ace