Question

As far as I know both tags import variables from tiles context to JSP so variables are made visible in the JSP. Please elaborate the difference between importAttribute and useAttribute.

Answer 1

Apparently there’s no difference between the two except that in useAttribute lets you specify the class name of the expected variable.

Here’s the code for importAttribute tag:

@Override
public void doTag() throws JspException {
    JspContext jspContext = getJspContext();
    Map<String, Object> attributes = model.getImportedAttributes(JspUtil
            .getCurrentContainer(jspContext), name, toName, ignore,
            jspContext);
    int scopeId = JspUtil.getScope(scopeName);
    for (Map.Entry<String, Object> entry : attributes.entrySet()) {
        jspContext.setAttribute(entry.getKey(), entry.getValue(), scopeId);
    }
}

and the code for useAttribute tag:

@Override
public void doTag() throws JspException {
    JspContext pageContext = getJspContext();
    Map<String, Object> attributes = model.getImportedAttributes(JspUtil
            .getCurrentContainer(pageContext), name, id, ignore,
            pageContext);
    if (!attributes.isEmpty()) {
        int scopeId = JspUtil.getScope(scopeName);
        pageContext.setAttribute(getScriptingVariable(), attributes
                .values().iterator().next(), scopeId);
    }
}