4 Replies Latest reply on Feb 12, 2007 10:28 AM by Thomas Diesler

    VirtualFile abstraction

    Thomas Diesler Master

      Carlo,

      I notice with the latest EJB3 backport to jboss42 there are a lot referrences to VirtualFile commented out. This is of course correct because jboss-vfs.jar cannot be used in jboss42.

      In jbossws we have a simmilar problem in our integration layers for the varios containers, wich we solved by introducing an UnifiedVirtualFile

      /**
       * An adaptor to a VirtualFile from jboss-vfs.jar
       * jboss-vfs cannot be used in jboss-4.x because of its dependeny on jboss-common-core.jar
       *
       * @author Thomas.Diesler@jboss.org
       * @since 05-May-2006
       */
      public interface UnifiedVirtualFile extends Serializable
      {
       UnifiedVirtualFile findChild(String child) throws IOException;
      
       URL toURL();
      }
      


      It turns out that we only need these two methods to find and read resources. There is a trivial implementation for jboss50 that delegates to a VirtualFile

      /**
       * A JBoss50 VirtualFile adaptor
       *
       * @author Thomas.Diesler@jboss.org
       * @since 05-May-2006
       */
      public class VirtualFileAdaptor implements UnifiedVirtualFile
      {
       private static final long serialVersionUID = 6547394037548338042L;
      
       private VirtualFile root;
      
       public VirtualFileAdaptor(VirtualFile root)
       {
       this.root = root;
       }
      
       public UnifiedVirtualFile findChild(String child) throws IOException
       {
       VirtualFile vf = root.findChild(child);
       return new VirtualFileAdaptor(vf);
       }
      
       public URL toURL()
       {
       try
       {
       return root.toURL();
       }
       catch (Exception e)
       {
       return null;
       }
       }
      }
      


      and one for jboss42 that uses a resource class loader

      /**
       * The default file adapter loads resources through an associated classloader.
       * If no classload is set, the the thread context classloader will be used.
       *
       * @author Heiko.Braun@jboss.org
       * @since 25.01.2007
       */
      public class ResourceLoaderAdapter implements UnifiedVirtualFile
      {
       private URL resourceURL;
       private ClassLoader loader;
      
       public ResourceLoaderAdapter()
       {
       this(Thread.currentThread().getContextClassLoader());
       }
      
       public ResourceLoaderAdapter(ClassLoader loader)
       {
       this.loader = loader;
       }
      
       private ResourceLoaderAdapter(ClassLoader loader, URL resourceURL)
       {
       this.resourceURL = resourceURL;
       this.loader = loader;
       }
      
       public UnifiedVirtualFile findChild(String resourcePath) throws IOException
       {
       URL resourceURL = null;
       if (resourcePath != null)
       {
       // Try the child as URL
       try
       {
       resourceURL = new URL(resourcePath);
       }
       catch (MalformedURLException ex)
       {
       // ignore
       }
      
       // Try the filename as File
       if (resourceURL == null)
       {
       try
       {
       File file = new File(resourcePath);
       if (file.exists())
       resourceURL = file.toURL();
       }
       catch (MalformedURLException e)
       {
       // ignore
       }
       }
      
       // Try the filename as Resource
       if (resourceURL == null)
       {
       try
       {
       resourceURL = loader.getResource(resourcePath);
       }
       catch (Exception ex)
       {
       // ignore
       }
       }
       }
      
       if (resourceURL == null)
       throw new IOException("Cannot get URL for: " + resourcePath);
      
       return new ResourceLoaderAdapter(loader, resourceURL);
       }
      
       public URL toURL()
       {
       if (null == this.resourceURL)
       throw new IllegalStateException("UnifiedVirtualFile not initialized");
       return resourceURL;
       }
      }
      


      Maybe this would solve your abstraction problem as well.

      cheers