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From mcconn...@apache.org
Subject cvs commit: avalon-sandbox/merlin/src/java/org/apache/avalon/merlin/block BlockLoader.java
Date Wed, 11 Dec 2002 04:58:55 GMT
mcconnell    2002/12/10 20:58:55

  Added:       merlin/src/java/org/apache/avalon/merlin/block
                        BlockLoader.java
  Log:
  Abstract of the functionality common to the kernel and blocks supporting the loading of
subsidiary blocks.
  
  Revision  Changes    Path
  1.1                  avalon-sandbox/merlin/src/java/org/apache/avalon/merlin/block/BlockLoader.java
  
  Index: BlockLoader.java
  ===================================================================
  /*
  
   ============================================================================
                     The Apache Software License, Version 1.1
   ============================================================================
  
   Copyright (C) 1999-2002 The Apache Software Foundation. All rights reserved.
  
   Redistribution and use in source and binary forms, with or without modifica-
   tion, are permitted provided that the following conditions are met:
  
   1. Redistributions of  source code must  retain the above copyright  notice,
      this list of conditions and the following disclaimer.
  
   2. Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
  
   3. The end-user documentation included with the redistribution, if any, must
      include  the following  acknowledgment:  "This product includes  software
      developed  by the  Apache Software Foundation  (http://www.apache.org/)."
      Alternately, this  acknowledgment may  appear in the software itself,  if
      and wherever such third-party acknowledgments normally appear.
  
   4. The names "Jakarta", "Apache Avalon", "Avalon Framework" and
      "Apache Software Foundation"  must not be used to endorse or promote
      products derived  from this  software without  prior written
      permission. For written permission, please contact apache@apache.org.
  
   5. Products  derived from this software may not  be called "Apache", nor may
      "Apache" appear  in their name,  without prior written permission  of the
      Apache Software Foundation.
  
   THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
   INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL  THE
   APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY DIRECT,
   INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLU-
   DING, BUT NOT LIMITED TO, PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS
   OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND ON
   ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR TORT
   (INCLUDING  NEGLIGENCE OR  OTHERWISE) ARISING IN  ANY WAY OUT OF THE  USE OF
   THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
   This software  consists of voluntary contributions made  by many individuals
   on  behalf of the Apache Software  Foundation. For more  information on the
   Apache Software Foundation, please see <http://www.apache.org/>.
  
  */
  
  package org.apache.avalon.merlin.block;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.FileInputStream;
  import java.io.InputStream;
  import java.net.URL;
  import java.util.ArrayList;
  import java.util.Enumeration;
  import java.util.jar.JarFile;
  import java.util.jar.Attributes;
  import java.util.jar.Manifest;
  import java.util.zip.ZipEntry;
  import java.net.JarURLConnection;
  
  import org.apache.avalon.framework.CascadingException;
  import org.apache.avalon.framework.logger.Logger;
  import org.apache.avalon.framework.activity.Initializable;
  import org.apache.avalon.framework.activity.Startable;
  import org.apache.avalon.framework.activity.Disposable;
  import org.apache.avalon.framework.configuration.Configuration;
  import org.apache.avalon.framework.configuration.Configurable;
  import org.apache.avalon.framework.configuration.ConfigurationException;
  import org.apache.avalon.framework.configuration.DefaultConfigurationBuilder;
  import org.apache.avalon.framework.configuration.DefaultConfiguration;
  import org.apache.avalon.framework.context.Context;
  import org.apache.avalon.framework.context.DefaultContext;
  import org.apache.avalon.framework.context.Contextualizable;
  import org.apache.avalon.framework.context.ContextException;
  import org.apache.avalon.framework.logger.AbstractLogEnabled;
  import org.apache.avalon.framework.service.DefaultServiceManager;
  import org.apache.avalon.meta.model.LoggingDirective;
  import org.apache.avalon.merlin.block.Block;
  import org.apache.avalon.merlin.block.DefaultBlock;
  import org.apache.avalon.merlin.container.builder.XMLContainerCreator;
  import org.apache.avalon.assembly.logging.LoggingManager;
  import org.apache.avalon.assembly.logging.LoggingDescriptor;
  import org.apache.avalon.assembly.logging.DefaultLoggingManager;
  import org.apache.avalon.assembly.engine.EngineClassLoader;
  import org.apache.avalon.assembly.engine.Engine;
  import org.apache.avalon.assembly.engine.model.LibraryDescriptor;
  import org.apache.avalon.assembly.engine.model.ClasspathDescriptor;
  import org.apache.avalon.assembly.util.ExceptionHelper;
  
  /**
   * Default kernel implementation.  The implementation provides support for
   * the following sequence of activties:
   *
   * <ul>
   * <li>loading internal jar-file dependencies
   * <li>establishment of a logging system
   * <li>creation of a root container
   * <li>startup of the container
   * <li>management of interupt conditions or request for kernel disposal
   * <li>error reporting
   * </ul>
   *
   * @see DefaultKernel
   *
   * @author <a href="mailto:avalon-dev@jakarta.apache.org">Avalon Development Team</a>
   * @version $Revision: 1.1 $ $Date: 2002/12/11 04:58:55 $
   */
  
  public class BlockLoader extends AbstractLogEnabled 
  {
      //==============================================================
      // static
      //==============================================================
  
      protected static final String BLOCK_XML_ENTRY = "BLOCK-INF/block.xml";
  
      protected static final XMLContainerCreator CREATOR = new XMLContainerCreator();
  
      //==============================================================
      // BlockLoader
      //==============================================================
  
      protected Block[] install( Engine engine, File home, URL[] urls ) throws Exception
      {
          ArrayList blocks = new ArrayList();
          for( int i=0; i<urls.length; i++ )
          {
              URL url = urls[i];
              try
              {
                  blocks.add( installBlock( engine, home, url ) );
              }
              catch( Throwable e )
              {
                  final String error = 
                    "Error during block deployment for url: " + url;
              }
          }
  
          Block[] result = (Block[]) blocks.toArray( new Block[0] );
  
          int n = result.length;
          if( n > 0 )
          {
              if( n > 1 )
              {
                  getLogger().debug( "installed " + urls.length + " blocks." );
              }
              else
              {
                  getLogger().debug( "installed one subsidiary block." );
              }
          }
  
          return result;
      }
  
      private Block installBlock( Engine engine, File home, URL url ) throws Exception
      {
           JarFile jar = getJarFile( url );
           Manifest manifest = jar.getManifest();
           if( !isBlock( manifest ) )
           {
               final String warning = 
                 "Manifest does not declare a block on resource: " + url;
               throw new IllegalArgumentException( warning );
           }
  
           Configuration blockConfig = getBlockConfiguration( jar );
  
           String name = DefaultBlock.getName( manifest );
           if( name == null )
           {
               final String error = "Missing name in block: " + url;
               throw new IllegalArgumentException( error );
           }
  
           Logger logger = getLogger().getChildLogger( name ) ;
           logger.debug( "[" + name + "]");
           DefaultBlock block = new DefaultBlock();
           block.enableLogging( logger );
           DefaultContext context = new DefaultContext();
           context.put( "urn:assembly:classloader", engine );
           context.put( "urn:merlin:block.manifest", manifest );
           context.put( "urn:merlin:block.url", url );
           context.put( "urn:avalon:home", home );
           context.makeReadOnly();
           block.contextualize( context );
           block.initialize();
           return block;
      }
  
      protected boolean isBlock( Manifest manifest )
      {
          if( manifest == null )
          {
              return false;
          }
          return ( manifest.getAttributes( Block.AVALON_BLOCK_KEY ) != null );
      }
  
      protected JarFile getJarFile( URL url )
      {
          try
          {
              JarURLConnection connection = (JarURLConnection) url.openConnection();
              return connection.getJarFile();
          }
          catch( IOException ioe )
          {
              final String error = 
                "Unexpected IO Exception while jar file from url: " + url;
              throw new RuntimeException( error );
          }
      }
  
      protected Configuration getBlockConfiguration( JarFile jar ) throws Exception
      {
          if( jar == null )
          {
              throw new NullPointerException( "jar" );
          }
  
          ZipEntry entry = jar.getEntry( BLOCK_XML_ENTRY );
          if( entry == null )
          {
              if( getLogger().isDebugEnabled() )
              {
                  final String msg = "No block configuration - applying defaults.";
                  getLogger().debug( msg );
              }
              return new DefaultConfiguration( "default", null );
          }
  
          try
          {
              DefaultConfigurationBuilder builder = new DefaultConfigurationBuilder();
              InputStream is = jar.getInputStream( entry );
              if( is == null )
              {
                  throw new RuntimeException(
                      "Could not load the configuration resource \"" + jar.getName() + "\""
);
              }
              return builder.build( is );
          }
          catch( Throwable e )
          {
              final String error = "Unable to create configuration from jar file: " + jar.getName();
              throw new BlockException( error, e );
          }
      }
  }
  
  
  

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