如何在JSP中使用c:url创建含路径变量的链接（不修改路由）？

Hey Rafael! Let's get this sorted out for you. The issue you're running into is that <c:url> doesn't natively handle path variable placeholders like {id} out of the box, but there's a straightforward way to generate the correct URL without touching your existing controller route.

First, Fix the Syntax Issue #

Looking at your code snippet, you missed quotes around the var attribute value, which might be causing immediate problems. Always wrap JSP tag attributes in quotes:

<!-- Wrong syntax -->
<c:url value="/movie/${session.id}/details" var=myURL>

<!-- Correct syntax -->
<c:url value="/movie/${session.id}/details" var="myURL">

Method 1: Direct EL String Concatenation with <c:url> #

Since your controller expects a path variable /movie/{id}/details, you can directly inject the session.id value into the URL path before passing it to <c:url>. The <c:url> tag will automatically handle adding your application's context path (if deployed under a subpath), which is the main benefit of using it over a raw anchor tag.

Here's the working code:

<c:url value="/movie/${session.id}/details" var="myURL" />
<a href="${myURL}">View Movie Details</a>

Method 2: Use JSTL Functions for Cleaner Template Replacement #

If you prefer a more structured approach (especially useful if you reuse the URL template elsewhere), you can use the JSTL Functions taglib to replace a placeholder in a base URL template.

First, add the functions taglib to your JSP:

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

Then use fn:replace to swap the placeholder with your session.id value:

<c:set var="baseMovieUrl" value="/movie/{id}/details" />
<c:set var="movieDetailsUrl" value="${fn:replace(baseMovieUrl, '{id}', session.id)}" />
<c:url value="${movieDetailsUrl}" var="myURL" />
<a href="${myURL}">View Movie Details</a>

Why Your Original Attempt Might Have Failed #

• Missing quotes on attributes: As mentioned, var=myURL should be var="myURL" to be valid JSP syntax.
• Empty session.id value: Double-check that session.id is actually populated with a valid integer when this JSP renders. If it's null or empty, the generated URL will be /movie//details, which won't match your controller route.

Both methods above will generate the exact URL your controller expects (/movie/{actual-id}/details) while leveraging <c:url> for context path handling, and you won't need to modify your existing @GetMapping("/movie/{id}/details") route at all.

内容的提问来源于stack exchange，提问作者Rafael Perracini