Question

Is possible to make output generated by my own JSP tags to be shorter ? For example tag defined as below generate 5 lines instead of 1. Is possible to avoid that (without join all 5 lines into 1 in tag source) ?

<%@ tag description="link" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ attribute name="href" required="true" type="java.lang.String" %>
<%@ attribute name="label" required="false" type="java.lang.String" %>
<a href="<c:url value="${href}"/>">${not empty label ? label : href}</a>

not a solution:

<%@ tag description="standard input" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><%@ attribute name="href" required="true" type="java.lang.String" description="address relative to web-app context" %><%@ attribute name="label" required="false" type="java.lang.String" description="link label" %><a href="<c:url value="${href}"/>">${not empty label ? label : href}</a>

Answer 1

Yes, you can globally configure the JSP parser to trim whitespace which are left by script expressions and tags.

Add this to your webapp’s web.xml (which has to be Servlet 2.5 compatible!):

<jsp-config>
    <jsp-property-group>
        <url-pattern>*.jsp</url-pattern>
        <trim-directive-whitespaces>true</trim-directive-whitespaces>
    </jsp-property-group>
</jsp-config>

If you target a Servlet 2.4 container or lower, then you have to edit container’s own web.xml instead to apply this globally. In Tomcat for example, it’s the /conf/web.xml file. Search for the <servlet> declaration of the JspServlet and add the following servlet init parameter inside the <servlet> declaration.

<init-param>
    <param-name>trimSpaces</param-name>
    <param-value>true</param-value>
</init-param>