Pass variable from a jsp file to a tag

I'm using tags to insert the body of my app into the global layout of the app. I'm trying to insert new css/js files (app specific) declared in the .jsp file, to the tag (not sure if I'm clear, but the codes should clarify that)

Here's my wrapper.tag file (a bit simplified) :

<%@ taglib prefix="spring" uri="http://www.springframework.org/tags"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@tag description="Wrapper Tag" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
    <title>Title of the page</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="robots" content="noindex,nofollow" />

    <!-- Bootstrap -->
    <!-- Latest compiled and minified CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

    <!-- Custom styles -->
    <spring:url value="/resources/core/css/style.css" var="coreCss" />
    <link href="${coreCss}" rel="stylesheet" />

    <!-- jQuery -->
    <script src="https://code.jquery.com/jquery-3.2.1.min.js" crossorigin="anonymous"></script>
    <!-- Bootstrap -->
    <!-- Latest compiled and minified JavaScript -->
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js" integrity="sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa" crossorigin="anonymous"></script>

    <!-- Custom scripts -->
    <spring:url value="/resources/core/js/script.js" var="coreJs" />
    <script src="${coreJs}"></script>
</head>
<body>
    <div class="content">
        <div class="app-content">
            <jsp:doBody/>
        </div>
    </div>
</body>
</html>

And here's an example of a jsp file that use that tag :

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib prefix="t" tagdir="/WEB-INF/tags" %>

<t:wrapper>
    <div class="container">
        <form class="form-signin">
            <h2 class="form-signin-heading">Please sign in</h2>
            <label for="inputEmail" class="sr-only">Email address</label>
            <input type="email" id="inputEmail" class="form-control" placeholder="Email address" required autofocus>

            <label for="inputPassword" class="sr-only">Password</label>
            <input type="password" id="inputPassword" class="form-control" placeholder="Password" required>

            <div class="checkbox">
                <label>
                    <input type="checkbox" value="remember-me"> Remember me
                </label>
            </div>

            <button class="btn btn-lg btn-primary btn-block" type="submit">Sign in</button>
        </form>
    </div>
</t:wrapper>

I would like to declare in the jsp files variables to insert new css/js files to load in the <head> of the wrapper tag.

Solution

I found a way, here's how to achieve that.

Just pass an attribute in the tag call in the jsp file:

<spring:url value="/resources/user/css/login.css" var="loginCss" />

<t:wrapper css="${loginCss}">

And add in the <head> of the wrapper tag:

<%@ attribute name="css" %>
<c:if test="${!empty css}" >
    <link href="${css}" rel="stylesheet" />
</c:if>

Same for JS.