package liquibase.servicelocator;

 import java.io.IOException;

 import java.net.URL;

 import java.util.Enumeration;

 /**

  * WebSphere specific resolver to handle loading annotated resources in JAR files.

  */

 public class WebSpherePackageScanClassResolver extends DefaultPackageScanClassResolver {

     private final String resourcePath;

     /**

      * Constructor.

      * 

      * @param resourcePath

      *            the fixed resource path to use for fetching camel jars in WebSphere.

      */

     public WebSpherePackageScanClassResolver(String resourcePath) {

         this.resourcePath = resourcePath;

     }

     /**

      * Is the classloader from IBM and thus the WebSphere platform?

      * 

      * @param loader

      *            the classloader

      * @return <tt>true</tt> if IBM classloader, <tt>false</tt> otherwise.

      */

     public static boolean isWebSphereClassLoader(ClassLoader loader) {

         return loader.getClass().getName().startsWith("com.ibm");

     }

     /**

      * Overloaded to handle specific problem with getting resources on the IBM WebSphere platform.

      * <p/>

      * WebSphere can <b>not</b> load resources if the resource to load is a folder name, such as a packagename, you have

      * to explicit name a resource that is a file.

      * 

      * @param loader

      *            the classloader

      * @param packageName

      *            the packagename for the package to load

      * @return URL's for the given package

      * @throws java.io.IOException

      *             is thrown by the classloader

      */

     @Override

     protected Enumeration<URL> getResources(ClassLoader loader, String packageName) throws IOException {

         // try super first, just in vase

         Enumeration<URL> enumeration = super.getResources(loader, packageName);

         if (!enumeration.hasMoreElements()) {

             log.debug("Using WebSphere workaround to load the camel jars with the annotated converters.");

             // Special WebSphere trick to load a file that exists in the JAR and then let it go from there.

             // The trick is that we just need the URL's for the .jars that contains the type

             // converters that is annotated. So by searching for this resource WebSphere is able to find

             // it and return the URL to the .jar file with the resource. Then the DefaultPackageScanClassResolver

             // can take it from there and find the classes that are annotated.

             enumeration = loader.getResources(resourcePath);

         }

         return enumeration;

     }

 }