BaseDocumentClassifier.java

/*
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distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache 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://www.apache.org/licenses/LICENSE-2.0

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specific language governing permissions and limitations
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*/

package org.apache.streams.converter;

import org.apache.streams.data.DocumentClassifier;
import org.apache.streams.data.util.ActivityUtil;
import org.apache.streams.jackson.StreamsJacksonMapper;
import org.apache.streams.pojo.json.Activity;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Ensures generic String and ObjectNode documents can be converted to Activity
 *
 * <p/>
 * BaseDocumentClassifier is included by default in all
 * @see org.apache.streams.converter.ActivityConverterProcessor
 *
 */
public class BaseDocumentClassifier implements DocumentClassifier {

  private ObjectMapper mapper = StreamsJacksonMapper.getInstance();

  private static final Logger LOGGER = LoggerFactory.getLogger(BaseDocumentClassifier.class);

  @Override
  @SuppressWarnings("unchecked")
  public List<Class> detectClasses(Object document) {

    Activity activity;
    ObjectNode node = null;

    List<Class> classes = new ArrayList<>();
    // Soon javax.validation will available in jackson
    //   That will make this simpler and more powerful
    if ( document instanceof String ) {
      classes.add(String.class);
      try {
        activity = this.mapper.readValue((String)document, Activity.class);
        if (activity != null && ActivityUtil.isValid(activity)) {
          classes.add(Activity.class);
        }
      } catch (IOException e1) {
        try {
          node = this.mapper.readValue((String)document, ObjectNode.class);
          classes.add(ObjectNode.class);
        } catch (IOException ignored) {
          LOGGER.trace("ignoring ", ignored);
        }
      }
    } else if ( document instanceof ObjectNode ) {
      classes.add(ObjectNode.class);
      activity = this.mapper.convertValue(document, Activity.class);
      if (ActivityUtil.isValid(activity)) {
        classes.add(Activity.class);
      }
    } else {
      classes.add(document.getClass());
    }

    return classes;

  }

}