WebObjects/Web Applications/Development/Custom Resource Manager

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Petite Abeille[edit]

Here is a little example on how to write your own WOResourceManager:

The main methods to implement are urlForResourceNamed() and bytesForResourceNamed().

  • urlForResourceNamed simply build an URL for a resource from wherever you would like (eg a jar file). Unfortunately, urlForResourceNamed uses pathForResourceNamed so you will need to rewrite that also:
 private URL urlForResourceNamed(String aResourceName)
 {
   return this.getClass().getResource( aResourceName );
 }
 
 public String pathForResourceNamed(String aResourceName, String aFrameworkName, NSArray someLanguages)
 {
   URL  anURL = this.urlForResourceNamed( aResourceName );
   
   if ( anURL != null )
   {
     return anURL.toExternalForm();
   }
   
   return null;
 }
 
 public String urlForResourceNamed(String aResourceName, String aFrameworkName, NSArray someLanguages, WORequest aRequest)
 {
   String  anURL = super.urlForResourceNamed( aResourceName, aFrameworkName, someLanguages, aRequest );
   
   this.bytesForResourceNamed( aResourceName, aFrameworkName, someLanguages );
 
   return anURL;
 }
  • bytesForResourceNamed simply retrieve a resource from wherever you would like (eg a jar file):
 public InputStream inputStreamForResourceNamed(String aResourceName, String aFrameworkName, NSArray someLanguages)
 {
   return this.getClass().getResourceAsStream( aResourceName );
 }
 
 public byte[] bytesForResourceNamed(String aResourceName, String aFrameworkName, NSArray someLanguages)
 {
   if ( aResourceName != null )
   {
     URL  anURL = this.urlForResourceNamed( aResourceName );
     
     if ( anURL != null )
     {
       String      aKey = anURL.toString();
       WOURLValuedElementData  anElement = (WOURLValuedElementData) _cache.get( aKey );
       
       if ( anElement == null )
       {
         synchronized( this )
         {
           InputStream  anInputStream = this.inputStreamForResourceNamed( aResourceName, null, null );
           
           if ( anInputStream != null )
           {
             try
             {
               InputStream  aBufferStream = new BufferedInputStream( anInputStream );
               byte[]    someBytes = new byte[ aBufferStream.available() ];
               
               aBufferStream.read( someBytes );
               aBufferStream.close();
               anInputStream.close();
   
               {
                 Data  someData = new Data( someBytes );
                 String  aType = this.contentTypeForResourceNamed( aKey );
                 
                 anElement = new WOURLValuedElementData( someData, aType, aKey );
                 
                 _cache.put( aKey, anElement );
               }
             }
             catch(Exception anException)
             {
               SZLog.warning( anException );
             }
           }
         }
       }
       
       return ( (Data) anElement.data() ).bytesNoCopy();
     }
     
     SZLog.debug( "Null url for resource named '" + aResourceName + "'." );
     
     return null;
   }
   
   throw new IllegalArgumentException ( "ResourceManager.bytesForResourceNamed: null resource name." );
 }
  • Last but not least, you need to take care of those funky WOURLValuedElementData so dataForResourceNamed will work:
 public NSData dataForResourceNamed(String aResourceName)
 {
   this.bytesForResourceNamed( aResourceName, null, null );
 
   String      aKey = this.urlForResourceNamed( aResourceName ).toString();
   WOURLValuedElementData  anElement = (WOURLValuedElementData) _cache.get( aKey );
   
   return anElement.data();
 }
  • Finally, you need to register your resource manager with WOApplication:
 anApplication.setResourceManager( new ResourceManager() );

Handling of languages and frameworks are left as an exercise to the reader.