TypeConverterProcessor.java

/*
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regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
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  http://www.apache.org/licenses/LICENSE-2.0

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*/

package org.apache.streams.converter;

import org.apache.streams.core.StreamsDatum;
import org.apache.streams.core.StreamsProcessor;
import org.apache.streams.jackson.StreamsJacksonMapper;

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

import java.io.Serializable;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

/**
 * TypeConverterProcessor converts between String json and jackson-compatible POJO objects.
 *
 * <p/>
 * Activity is one supported jackson-compatible POJO, so JSON String and objects with structual similarities
 *   to Activity can be converted to Activity objects.
 *
 * <p/>
 * However, conversion to Activity should probably use {@link org.apache.streams.converter.ActivityConverterProcessor}
 *
 */
public class TypeConverterProcessor implements StreamsProcessor, Serializable {

  public static final String STREAMS_ID = "TypeConverterProcessor";

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

  private List<String> formats = new ArrayList<>();

  protected ObjectMapper mapper;

  protected Class outClass;

  public TypeConverterProcessor(Class outClass) {
    this.outClass = outClass;
  }

  public TypeConverterProcessor(Class outClass, List<String> formats) {
    this(outClass);
    this.formats = formats;
  }

  @Override
  public String getId() {
    return STREAMS_ID;
  }

  @Override
  public List<StreamsDatum> process(StreamsDatum entry) {

    List<StreamsDatum> result = new LinkedList<>();
    Object inDoc = entry.getDocument();

    Object outDoc = TypeConverterUtil.getInstance().convert(inDoc, outClass, mapper);

    if ( outDoc != null ) {
      entry.setDocument(outDoc);
      result.add(entry);
    }

    return result;
  }

  @Override
  public void prepare(Object configurationObject) {
    if ( formats.size() > 0 ) {
      this.mapper = StreamsJacksonMapper.getInstance(formats);
    } else {
      this.mapper = StreamsJacksonMapper.getInstance();
    }
  }

  @Override
  public void cleanUp() {
    this.mapper = null;
  }

}