Programmatic Servlet 3.0 JSP jsp-property-group configuration

Question

I am able to create servlets and filters in my ServletContainerInitializer, but is it possible to translate this last remaining piece of an old web.xml into Servlet 3.0 programmatic configuration?

<jsp-config>
    <jsp-property-group>
        <url-pattern>*.jsp</url-pattern>
        <page-encoding>UTF-8</page-encoding>
        <trim-directive-whitespaces>true</trim-directive-whitespaces>
    </jsp-property-group>
</jsp-config>

Answer 1

Servlet 3.x specifies only the reading interface for JSP settings.

To write JSP settings, one need to access the JSP engine implementation, or continue using web.xml. The latter is not a big issue since web.xml can safely coexist with ServletContainerInitializer. So advise is to keep web.xml.

It is however an issue with Spring Boot, which ignores web.xml.

With Spring Boot 2 with an embedded Tomcat it can be achieved using TomcatContextCustomizer:

@Component
public class JspConfig implements TomcatContextCustomizer {
    @Override
    public void customize(Context context) {
        JspPropertyGroup pg = new JspPropertyGroup();
        pg.addUrlPattern("/*");
        pg.setPageEncoding("UTF-8");
        pg.setTrimWhitespace("true");
        ArrayList<JspPropertyGroupDescriptor> pgs = new ArrayList<>();
        pgs.add(new JspPropertyGroupDescriptorImpl(pg));
        context.setJspConfigDescriptor(new JspConfigDescriptorImpl(pgs, new ArrayList<TaglibDescriptor>()));
    }
}