IncludeResourcesFilter.java

import com.atlassian.jira.ComponentManager;
import com.atlassian.plugin.webresource.WebResourceManager;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import org.apache.commons.lang.StringUtils;

import javax.servlet.*;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class IncludeResourcesFilter implements Filter
{
// ------------------------------ FIELDS ------------------------------

    private static final String DEPENDENCIES = "resources";
    private static final char SEPARATOR_CHAR = ';';

    private List<String> resourceDependencies = Collections.emptyList();

// --------------------- GETTER / SETTER METHODS ---------------------

    public List<String> getResourceDependencies()
    {
        return resourceDependencies;
    }

// ------------------------ INTERFACE METHODS ------------------------

// --------------------- Interface Filter ---------------------

    public void init(final FilterConfig filterConfig) throws ServletException
    {
        resourceDependencies = ImmutableList.copyOf(getDependencies(filterConfig));
    }

    public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain)
            throws IOException, ServletException
    {
        doIncludeResources(getWebResourceManager(), getResourceDependencies());
        filterChain.doFilter(servletRequest, servletResponse);
    }

    public void destroy()
    {
    }

// -------------------------- OTHER METHODS --------------------------

    private void doIncludeResources(WebResourceManager webResourceManager, Iterable<String> resourceDependencies)
    {
        for (String dependency : resourceDependencies)
        {
            webResourceManager.requireResource(dependency);
        }
    }

    private List<String> getDependencies(FilterConfig filterConfig)
    {
        List<String> dependencies = Lists.newArrayListWithCapacity(2);
        for (String dependency : getResourceDependencies(filterConfig))
        {
            if (StringUtils.isNotBlank(dependency))
            {
                dependencies.add(dependency);
            }
        }
        return dependencies;
    }

    private List<String> getResourceDependencies(FilterConfig filterConfig)
    {
        return Arrays.asList(
                StringUtils.split(StringUtils.defaultString(filterConfig.getInitParameter(DEPENDENCIES)), SEPARATOR_CHAR));
    }

    private WebResourceManager getWebResourceManager() {return ComponentManager.getInstance().getWebResourceManager();}
}