URIHandlerImpl.java

/**
 * Copyright (c) 2007-2011 IBM Corporation and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   IBM - Initial API and implementation
 */
package org.eclipse.emf.ecore.resource.impl;


import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import org.eclipse.emf.common.util.Callback;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.ContentHandler;
import org.eclipse.emf.ecore.resource.URIConverter;
import org.eclipse.emf.ecore.resource.URIHandler;


/**
 * An implementation of a {@link URIHandler URI handler}.
 *
 */
public class URIHandlerImpl implements URIHandler
{
  /**
   * Creates an instance.
   */
  public URIHandlerImpl()
  {
    super();
  }

  /**
   * This implementation always returns true; clients are generally expected to override this.
   */
  public boolean canHandle(URI uri)
  {
    return true;
  }

  /**
   * Returns the value of the {@link URIConverter#OPTION_URI_CONVERTER URI converter option}.
   * @param options the options in which to look for the URI converter.
   * @return the value of the URI converter option.
   */
  protected URIConverter getURIConverter(Map<?, ?> options)
  {
    return (URIConverter)options.get(URIConverter.OPTION_URI_CONVERTER);
  }

  /**
   * Returns the value of the {@link URIConverter#OPTION_RESPONSE response option}.
   * @param options the options in which to look for the response option.
   * @return the value of the response option.
   */
  @SuppressWarnings("unchecked")
  protected Map<Object, Object> getResponse(Map<?, ?> options)
  {
    return (Map<Object, Object>)options.get(URIConverter.OPTION_RESPONSE);
  }

  /**
   * Returns the value of the {@link URIConverter#OPTION_REQUESTED_ATTRIBUTES requested attributes option}.
   * @param options the options in which to look for the requested attributes option.
   * @return the value of the requested attributes option.
   */
  @SuppressWarnings("unchecked")
  protected Set<String> getRequestedAttributes(Map<?, ?> options)
  {
    return (Set<String>)options.get(URIConverter.OPTION_REQUESTED_ATTRIBUTES);
  }

  /**
   * Creates an output stream for the URI, assuming it's a URL, and returns it.
   * Specialized support is provided for HTTP URLs.
   * @return an open output stream.
   * @exception IOException if there is a problem obtaining an open output stream.
   */
  public OutputStream createOutputStream(URI uri, Map<?, ?> options) throws IOException
  {
    return null;
  }

  public void store(URI uri, byte[] bytes, Map<?, ?> options, Callback<Map<?, ?>> callback)
  {
    callback.onSuccess(null);
  }

  /**
   * Creates an input stream for the URI, assuming it's a URL, and returns it.
   * @return an open input stream.
   * @exception IOException if there is a problem obtaining an open input stream.
   */
  public InputStream createInputStream(URI uri, Map<?, ?> options) throws IOException
  {
    return null;
  }

  public void createInputStream(URI uri, Map<?, ?> options, Callback<Map<?, ?>> callback)
  {
    callback.onSuccess(null);
  }

  /**
   * Only HTTP connections support delete.
   */
  public void delete(URI uri, Map<?, ?> options) throws IOException
  {
    //
  }

  public void delete(URI uri, Map<?, ?> options, Callback<Map<?, ?>> callback)
  {
    callback.onSuccess(null);
  }

  /**
   * This implementation delegates to the {@link #getURIConverter(Map) URI converter}'s {@link URIConverter#getContentHandlers() content handlers}.
   */
  public Map<String, ?> contentDescription(URI uri, Map<?, ?> options) throws IOException
  {
    URIConverter uriConverter = (URIConverter)options.get(URIConverter.OPTION_URI_CONVERTER);
    InputStream inputStream = null;
    Map<String, ?> result = null;
    Map<Object, Object> context = new HashMap<Object, Object>();
    try
    {
      for (ContentHandler contentHandler : uriConverter.getContentHandlers())
      {
        if (contentHandler.canHandle(uri))
        {
          if (inputStream == null)
          {
            try
            {
              inputStream = createInputStream(uri, options);
            }
            catch (IOException exception)
            {
              throw exception;
            }
            if (!inputStream.markSupported())
            {
              // inputStream = new BufferedInputStream(inputStream);
            }
            inputStream.mark(Integer.MAX_VALUE);
          }
          else
          {
            inputStream.reset();
          }
          Map<String, ?> contentDescription = contentHandler.contentDescription(uri, inputStream, options, context);
          switch ((ContentHandler.Validity)contentDescription.get(ContentHandler.VALIDITY_PROPERTY))
          {
            case VALID:
            {
              return contentDescription;
            }
            case INDETERMINATE:
            {
              if (result == null)
              {
                result = contentDescription;
              }
              break;
            }
            case INVALID:
            {
              break;
            }
          }
        }
      }
    }
    finally
    {
      if (inputStream != null)
      {
        inputStream.close();
      }
    }

    return result == null ? ContentHandler.INVALID_CONTENT_DESCRIPTION : result;
  }

  /**
   * If a stream can be created the file exists.
   * Specialized support is provided for HTTP connections to avoid fetching the whole stream in that case.
   */
  public boolean exists(URI uri, Map<?, ?> options)
  {
    return false;
  }

  public void exists(URI uri, Map<?, ?> options, Callback<Boolean> callback)
  {
    callback.onSuccess(false);
  }

  public Map<String, ?> getAttributes(URI uri, Map<?, ?> options)
  {
    return null;
  }

  public void setAttributes(URI uri, Map<String, ?> attributes, Map<?, ?> options) throws IOException
  {
    // We can't update any properties via just a URL connection.
  }
}