odata2-lib/odata-core/src/main/java/org/apache/olingo/odata2/core/ep/producer/JsonCollectionEntityProducer.java

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 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * 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
 * 
 * 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
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package org.apache.olingo.odata2.core.ep.producer;

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

import org.apache.olingo.odata2.api.edm.Edm;
import org.apache.olingo.odata2.api.edm.EdmException;
import org.apache.olingo.odata2.api.ep.EntityProviderException;
import org.apache.olingo.odata2.core.ep.EntityProviderProducerException;
import org.apache.olingo.odata2.core.ep.aggregator.EntityPropertyInfo;
import org.apache.olingo.odata2.core.ep.util.FormatJson;
import org.apache.olingo.odata2.core.ep.util.JsonStreamWriter;

/**
 * Provider for writing a collection of simple-type or complex-type instances in JSON.
 * 
 */
public class JsonCollectionEntityProducer {

  public void append(final Writer writer, final EntityPropertyInfo propertyInfo, final List<?> data)
      throws EntityProviderException {
    JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(writer);

    try {
      jsonStreamWriter.beginObject()
          .name(FormatJson.D)
          .beginObject();

      jsonStreamWriter.name(FormatJson.METADATA)
          .beginObject()
          .namedStringValueRaw(
              FormatJson.TYPE,
              "Collection(" + propertyInfo.getType().getNamespace() + Edm.DELIMITER + propertyInfo.getType().getName()
                  + ")")
          .endObject()
          .separator();

      jsonStreamWriter.name(FormatJson.RESULTS)
          .beginArray();
      boolean first = true;
      for (final Object item : data) {
        if (first) {
          first = false;
        } else {
          jsonStreamWriter.separator();
        }
        JsonPropertyEntityProducer.appendPropertyValue(jsonStreamWriter, propertyInfo, item, true);
      }
      jsonStreamWriter.endArray();

      jsonStreamWriter.endObject()
          .endObject();
    } catch (final IOException e) {
      throw new EntityProviderProducerException(EntityProviderException.EXCEPTION_OCCURRED.addContent(e.getClass()
          .getSimpleName()), e);
    } catch (final EdmException e) {
      throw new EntityProviderProducerException(e.getMessageReference(), e);
    }
  }
}