integration_test/src/java/com/twitter/heron/integration_test/common/HdfsHelper.java

// Copyright 2016 Twitter. All rights reserved.
//
// Licensed 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.
package com.twitter.heron.integration_test.common;

import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

/**
 * A helper class abstracting away the interaction with HDFS
 * Note: Adding these helper method directly in the spout code results
 * in a ClassNotFoundException for hadoop classes, while deploying a topology, even though
 * those classes are not being accessed during deploy.
 */
public final class HdfsHelper {

  private HdfsHelper() {
  }

  /**
   * Provide an InputStreamReader to read from a hdfs file
   *
   * @param path is the hdfs file location
   */
  public static InputStreamReader getHdfsStreamReader(String path) throws IOException {
    Path pt = new Path(path);
    Configuration conf = new Configuration();
    FileSystem fileSystem = FileSystem.get(conf);
    return new InputStreamReader(fileSystem.open(pt), StandardCharsets.UTF_8);
  }
}