CutdownPackageResourceStreamLocator.java

import java.util.Arrays;
import java.util.List;
import java.util.ListIterator;

import org.apache.wicket.util.resource.IResourceStream;
import org.apache.wicket.util.resource.locator.ResourceStreamLocator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Locate Wicket resource by path removed a specified package-depth.
 * <h3>Usage</h3>
 * <pre>
 * getResourceSettings().setResourceStreamLocator(CutdownPackageResourceStreamLocator.newInstance(1));
 * </pre>
 * <h4>Example</h4>
 * In case of setting 2 for package depth.
 * <ul>
 *  <li>com/example/Homepage.html => HomePage.html</li>
 *  <li>com/example/item/ItemPage.html => item/ItemPage.html</li>
 *  <li>com/SamplePage.properties => com/SamplePage.properties</li>
 * </ul> 
 *
 */
public class CutdownPackageResourceStreamLocator extends ResourceStreamLocator {

    private static final Logger logger = LoggerFactory.getLogger(CutdownPackageResourceStreamLocator.class);

    private final int packageDepth;

    private CutdownPackageResourceStreamLocator(int packageDepth) {
        this.packageDepth = packageDepth;
    }

    public static CutdownPackageResourceStreamLocator newInstance() {
        return new CutdownPackageResourceStreamLocator(0);
    }

    public static CutdownPackageResourceStreamLocator newInstance(int packageDepth) {
        return new CutdownPackageResourceStreamLocator(packageDepth);
    }

    /*
     * (non-Javadoc)
     * @see org.apache.wicket.util.resource.locator.ResourceStreamLocator#locate(java.lang.Class, java.lang.String)
     */
    @Override
    public IResourceStream locate(Class<?> clazz, String path) {
        String resolvedPath = cutdownPackageFromPath(clazz, path);
        logger.debug("searching {}.", resolvedPath);
        IResourceStream located = super.locate(clazz, resolvedPath);
        if (located != null) {
            return located;
        }
        return super.locate(clazz, path);
    }

    String cutdownPackageFromPath(final Class<?> clazz, final String path) {
        List<String> packageNameList = 
            Arrays.asList(clazz.getPackage().getName().split("\\."));
        int type = packageNameList.size() >= packageDepth ? packageNameList.size() - packageDepth : -1;
        // case: Number of packages is larger than depth.
        if (type > 0) {
            StringBuilder sb = new StringBuilder();
            for (ListIterator<String> itor = packageNameList.listIterator(packageDepth); itor.hasNext();) {
                sb.append(String.valueOf(itor.next()));
                sb.append('/');
            }
            int start = path.indexOf(sb.toString());
            if (start == -1) {
                return path;
            }
            return path.substring(start);
        // case: Number of packages equals depth.
        } else if (type == 0) {
            int start = path.lastIndexOf('/');
            if (start == -1) {
                return path;
            }
            return path.substring(start + 1);
        } else {
            // do nothing.
            return path;
        }
    }
}