blobstore/src/main/java/org/jclouds/blobstore/config/BlobStoreObjectModule.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jclouds.blobstore.config;

import javax.inject.Inject;
import javax.inject.Provider;

import org.jclouds.blobstore.domain.Blob;
import org.jclouds.blobstore.domain.MutableBlobMetadata;
import org.jclouds.blobstore.domain.internal.BlobImpl;

import com.google.inject.AbstractModule;
import com.google.inject.Provides;
import com.google.inject.Scopes;

/**
 * Configures the domain object mappings needed for all Blob implementations
 */
public class BlobStoreObjectModule extends AbstractModule {

   /**
    * explicit factories are created here as it has been shown that Assisted Inject is extremely
    * inefficient. http://code.google.com/p/google-guice/issues/detail?id=435
    */
   @Override
   protected void configure() {
      bind(Blob.Factory.class).to(BlobFactory.class).in(Scopes.SINGLETON);
   }

   private static class BlobFactory implements Blob.Factory {

      @Inject
      Provider<MutableBlobMetadata> metadataProvider;

      public Blob create(MutableBlobMetadata metadata) {
         return new BlobImpl(metadata != null ? metadata : metadataProvider.get());
      }
   }

   @Provides
   final Blob provideBlob(Blob.Factory factory) {
      return factory.create(null);
   }

}