SchemaLoader.java

/**
 * Copyright (c) 2013, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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.
 */
package com.cloudera.science.avro.common;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;

import org.apache.avro.Schema;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

import eu.dnetlib.iis.common.utils.AvroUtils;
/**
 * Some changes introduced in the original code by Mateusz Kobos
 */
public class SchemaLoader {
  
  private final Configuration conf;
  private final Schema.Parser parser = new Schema.Parser();
  
  public SchemaLoader(Configuration conf) {
    this.conf = conf;
  }
  
  public Schema load(String schemaJson, String schemaUrl, String typeName) throws IOException {
    if (schemaJson != null && !"none".equals(schemaJson)) {
      return loadLiteral(schemaJson);
    } else if (schemaUrl != null && !"none".equals(schemaUrl)) {
      return loadFromUrl(schemaUrl);
    } else if (typeName != null && !"none".equals(typeName)) {
      return loadFromTypeName(typeName);
    } else {
      throw new IllegalArgumentException("No valid schema information provided");
    }
  }
  
  public Schema loadLiteral(String schemaJson) throws IOException {
    return parser.parse(schemaJson);
  }
  
  public Schema loadFromUrl(String schemaUrl) throws IOException {
    if (schemaUrl.toLowerCase().startsWith("hdfs://")) {
      FileSystem fs = FileSystem.get(conf);
      FSDataInputStream input = null;
      try {
        input = fs.open(new Path(schemaUrl));
        return parser.parse(input);
      } finally {
        if (input != null) {
          input.close();
        }
      }
    } else {
      InputStream is = null;
      try {
        is = new URL(schemaUrl).openStream();
        return parser.parse(is);
      } finally {
        if (is != null) {
          is.close();
        }
      }
    }
  }
  
  public Schema loadFromTypeName(String typeName) {
    return AvroUtils.toSchema(typeName);
  }
}