JaxbParser.java

/**
 * Licensed to The Apereo Foundation under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 *
 * The Apereo Foundation licenses this file to you under the Educational
 * Community 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://opensource.org/licenses/ecl2.txt
 *
 * 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.opencastproject.util.jaxb;

import static org.opencastproject.util.data.functions.Misc.chuck;

import org.apache.commons.io.IOUtils;

import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.io.Writer;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;

/** Base class for JAXB parser classes. */
public abstract class JaxbParser {
  private final JAXBContext ctx;

  /**
   * Create a new parser.
   *
   * @param contextPath see {@link javax.xml.bind.JAXBContext#newInstance(String, ClassLoader)}
   */
  protected JaxbParser(String contextPath) {
    this.ctx = init(contextPath);
  }

  private JAXBContext init(String contextPath) {
    try {
      return JAXBContext.newInstance(contextPath, this.getClass().getClassLoader());
    } catch (JAXBException e) {
      return chuck(e);
    }
  }

  public JAXBContext getCtx() {
    return ctx;
  }

  /** Unmarshal an instance of class <code>dtoClass</code> from <code>source</code> and close it. */
  public <A> A unmarshal(Class<A> dtoClass, InputStream source) throws IOException {
    try {
      final Unmarshaller unmarshaller = ctx.createUnmarshaller();
      return unmarshaller.unmarshal(new StreamSource(source), dtoClass).getValue();
    } catch (Exception e) {
      throw new IOException(e);
    } finally {
      IOUtils.closeQuietly(source);
    }
  }

  /**
   * Marshal an object into a string.
   */
  public String marshal(Object o) throws IOException {
    try {
      final Marshaller marshaller = ctx.createMarshaller();
      final Writer writer = new StringWriter();
      marshaller.marshal(o, writer);
      return writer.toString();
    } catch (JAXBException e) {
      throw new IOException(e);
    }
  }
}