BinaryValueURLLoader.java

/*
 * Copyright (c) 2017 OBiBa. All rights reserved.
 *
 * This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.obiba.magma.support;

import java.io.InputStream;
import java.net.URL;

import javax.validation.constraints.NotNull;

import org.obiba.magma.MagmaRuntimeException;
import org.obiba.magma.ValueLoader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.io.ByteStreams;

/**
 * Loads a binary value from a url.
 */
public class BinaryValueURLLoader implements ValueLoader {

  private static final long serialVersionUID = -8549264329027093382L;

  private static final Logger log = LoggerFactory.getLogger(BinaryValueURLLoader.class);

  private final String url;

  private byte[] value;

  public BinaryValueURLLoader(String url) {
    this.url = url;
  }

  @Override
  public boolean isNull() {
    return url == null || url.isEmpty();
  }

  @NotNull
  @Override
  @edu.umd.cs.findbugs.annotations.SuppressWarnings("EI_EXPOSE_REP")
  public Object getValue() {
    if(value == null) {
      try {
        log.debug("Loading binary from: {}", url);
        URL u = new URL(url);
        try(InputStream in = u.openStream()) {
          value = ByteStreams.toByteArray(in);
        }
        log.debug("Binary loaded from: {}", url);
      } catch(Exception e) {
        value = null;
        throw new MagmaRuntimeException("URL cannot be read: " + url, e);
      }
    }
    return value;
  }

  /**
   * Downloads the value to get its size.
   *
   * @return
   */
  @Override
  public long getLength() {
    getValue();
    return value == null ? 0 : value.length;
  }

}