com.oculusinfo.tile.util.AvroJSONConverter.java Source code

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Here is the source code for com.oculusinfo.tile.util.AvroJSONConverter.java

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/*
 * Copyright (c) 2014 Oculus Info Inc.
 * http://www.oculusinfo.com/
 *
 * Released under the MIT License.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.oculusinfo.tile.util;

import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.FileReader;
import org.apache.avro.file.SeekableByteArrayInput;
import org.apache.avro.file.SeekableInput;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.io.JsonEncoder;
import org.apache.commons.io.IOUtils;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * Simple utility class to convert Avro files to JSON (and, maybe, vice versa)
 * 
 * @author nkronenfeld
 */
public class AvroJSONConverter {
    /**
     * Convert an Avro input stream into a JSON object
     * 
     * @param stream The input data
     * @return A JSON representation of the input data
     * @throws IOException
     * @throws JSONException
     */
    public static JSONObject convert(InputStream stream) throws IOException, JSONException {
        SeekableInput input = new SeekableByteArrayInput(IOUtils.toByteArray(stream));
        ByteArrayOutputStream output = new ByteArrayOutputStream();

        // Conversion code taken from org.apache.avro.tool.DataFileReadTool
        GenericDatumReader<Object> reader = new GenericDatumReader<Object>();
        FileReader<Object> fileReader = DataFileReader.openReader(input, reader);
        try {
            Schema schema = fileReader.getSchema();
            DatumWriter<Object> writer = new GenericDatumWriter<Object>(schema);
            JsonEncoder encoder = EncoderFactory.get().jsonEncoder(schema, output);
            for (Object datum : fileReader) {
                encoder.configure(output);
                writer.write(datum, encoder);
                encoder.flush();
                // For some reason, we only contain one record, but the 
                // decoding thinks we contain more and fails; so just break 
                // after our first one.
                break;
            }
            output.flush();
        } finally {
            fileReader.close();
        }
        String jsonString = output.toString("UTF-8");
        return new JSONObject(jsonString);
    }
}