Android Open Source - interdroid-vdb Avro Content Provider Proxy

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Copyright (c) 2008-2012 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...

Java Source Code

/*
 * Copyright (c) 2008-2012 Vrije Universiteit, The Netherlands All rights
 * reserved./*from ww  w.  j  a  va2 s  .  c  om*/
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * 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.
 *
 * Neither the name of the Vrije Universiteit nor the names of its contributors
 * may be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, 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.
 */
package interdroid.vdb.content.avro;

import java.io.IOException;

import interdroid.vdb.Authority;
import interdroid.vdb.content.ContentChangeHandler;
import interdroid.vdb.content.CrossProcessCursorWrapper;
import interdroid.vdb.content.EntityUriMatcher;
import interdroid.vdb.content.EntityUriMatcher.UriMatch;

import org.apache.avro.Schema;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.pm.ProviderInfo;
import android.database.Cursor;
import android.net.Uri;

/**
 * Proxies for a remote content provider that is using an avro content provider.
 *
 * @author nick <palmer@cs.vu.nl>
 *
 */
public class AvroContentProviderProxy extends ContentProvider {

  /**
   * Access to logger.
   */
  private static final Logger LOG =
      LoggerFactory.getLogger(AvroContentProviderProxy.class);

  // TODO: Need to proxy content change delete update etc notifications.
  // TODO: Need to check for installation of vdb-ui.

  /**
   * The schema for the provider.
   */
  private final Schema mSchema;

  /**
   * Constructs a proxy for a provider using the given schema.
   * @param schema the schema for the provider
   */
  public AvroContentProviderProxy(final String schema) {
    this(Schema.parse(schema));
  }

  /**
   * Constructs a proxy for a provider using the given schema.
   * @param schema the schema for the provider
   */
  public AvroContentProviderProxy(final Schema schema) {
    LOG.debug("Constructing provider proxy.");
    mSchema = schema;
  }

  /**
   * Remaps a URI from the native URI to the internal URI.
   * @param uri the uri to remap to an internal URI
   * @return the internal URI equivalent
   */
  private Uri remapUri(final Uri uri) {
    // TODO: This should be done with EntityURIBuilder no?
    Uri.Builder builder = new Uri.Builder();
    builder.scheme(uri.getScheme());
    builder.authority(Authority.VDB);
    builder.path(uri.getAuthority() + uri.getPath());
    builder.query(uri.getQuery());
    Uri built = builder.build();
    LOG.debug("remapped: {} to {}", uri, built);
    return built;
  }

  @Override
  public final int delete(final Uri uri, final String selection,
      final String[] selectionArgs) {
    return getContext().getContentResolver().delete(
        remapUri(uri), selection, selectionArgs);
  }

  @Override
  public final String getType(final Uri uri) {
    return getContext().getContentResolver().getType(remapUri(uri));
  }

  @Override
  public final Uri insert(final Uri uri, final ContentValues values) {
    final UriMatch result = EntityUriMatcher.getMatch(uri);
    ContentChangeHandler handler =
        ContentChangeHandler.getHandler(
            result.authority, result.entityName);
    if (handler != null) {
      handler.preInsertHook(values);
    }
    Context context = getContext();
    ContentResolver resolver = context.getContentResolver();
    Uri mappedUri = remapUri(uri);
    LOG.debug("Inserting into:" + mappedUri + " values: " + values);

    return resolver.insert(mappedUri, values);
  }

  @Override
  public final void attachInfo(final Context context,
      final ProviderInfo info) {
    super.attachInfo(context, info);

    // Make sure we are registered.
    LOG.debug("attachInfo");
    LOG.debug("Registering schema: {}", mSchema.getName());

    try {
      AvroSchemaRegistrationHandler.registerSchema(context, mSchema);
    } catch (IOException e) {
      LOG.error("Caught IOException while registering.", e);
    }

  }

  @Override
  public final Cursor query(final Uri uri, final String[] projection,
      final String selection, final String[] selectionArgs,
      final String sortOrder) {
    return new CrossProcessCursorWrapper(getContext()
        .getContentResolver().query(
            remapUri(uri), projection,
            selection, selectionArgs, sortOrder));
  }

  @Override
  public final int update(final Uri uri, final ContentValues values,
      final String selection, final String[] selectionArgs) {
    return getContext().getContentResolver().update(
        remapUri(uri), values, selection, selectionArgs);
  }

  @Override
  public final boolean onCreate() {
    return false;
  }

}

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