com.topsoft.botspider.util.AvroReadTool.java Source code

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Here is the source code for com.topsoft.botspider.util.AvroReadTool.java

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package com.topsoft.botspider.util;
/**
 * 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 under the License.
 */

import java.io.InputStream;
import java.io.PrintStream;
import java.util.List;

import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.FileReader;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import com.topsoft.botspider.avro.mapreduce.FsInput;
import com.topsoft.botspider.io.MapAvroFile;

/** Reads a data file and dumps to JSON */
public class AvroReadTool implements Tool {

    @Override
    public String getName() {
        return "tojson";
    }

    @Override
    public String getShortDescription() {
        return "Dumps an Avro data file as JSON, one record per line.";
    }

    @Override
    public int run(InputStream stdin, PrintStream out, PrintStream err, List<String> args) throws Exception {
        if (args.size() < 1) {
            // Unlike other commands, "-" can't be used for stdin, because
            // we can only use seekable files.
            err.println("Usage: input_file [-num numToRead].");
            return 1;
        }
        int numToRead = Integer.MIN_VALUE;

        for (int i = 0; i < args.size(); i++) {
            if ("-num".equals(args.get(i))) {
                numToRead = Integer.parseInt(args.get(i + 1));
                i++;
            }
        }
        Configuration conf = new Configuration();
        FileSystem fs = FileSystem.get(conf);
        Path inputFile = new Path(args.get(0));
        if (fs.isDirectory(inputFile)) {
            inputFile = new Path(inputFile, MapAvroFile.DATA_FILE_NAME);
        }

        GenericDatumReader<Object> reader = new GenericDatumReader<Object>();
        FileReader<Object> fileReader = new DataFileReader<Object>(new FsInput(inputFile, conf), reader);
        try {
            Schema schema = fileReader.getSchema();
            DatumWriter<Object> writer = new GenericDatumWriter<Object>(schema);
            Encoder encoder = EncoderFactory.get().jsonEncoder(schema, out);
            for (Object datum : fileReader) {
                if (Integer.MIN_VALUE == numToRead || numToRead-- > 0) {
                    //encoder.init(out);
                    writer.write(datum, encoder);
                    encoder.flush();
                    //out.println();
                } else
                    break;
            }
            out.flush();
        } finally {
            fileReader.close();
        }
        return 0;
    }

}