org.apache.hadoop.mapred.OutputFormat#getRecordWriter ( )源码实例Demo

@Test(enabled = true)
public void testWriteChunkData() throws Exception {
  NullWritable nada = NullWritable.get();
  MneDurableOutputSession<DurableChunk<?>> sess =
          new MneDurableOutputSession<DurableChunk<?>>(m_tacontext, null,
                  MneConfigHelper.DEFAULT_OUTPUT_CONFIG_PREFIX);
  MneDurableOutputValue<DurableChunk<?>> mdvalue =
          new MneDurableOutputValue<DurableChunk<?>>(sess);
  OutputFormat<NullWritable, MneDurableOutputValue<DurableChunk<?>>> outputFormat =
          new MneOutputFormat<MneDurableOutputValue<DurableChunk<?>>>();
  RecordWriter<NullWritable, MneDurableOutputValue<DurableChunk<?>>> writer =
          outputFormat.getRecordWriter(null, m_conf, null, null);
  DurableChunk<?> dchunk = null;
  Checksum cs = new CRC32();
  cs.reset();
  for (int i = 0; i < m_reccnt; ++i) {
    dchunk = genupdDurableChunk(sess, cs);
    Assert.assertNotNull(dchunk);
    writer.write(nada, mdvalue.of(dchunk));
  }
  m_checksum = cs.getValue();
  writer.close(null);
  sess.close();
}
 

@Test(enabled = true)
public void testWriteLongData() throws Exception {
  NullWritable nada = NullWritable.get();
  MneDurableOutputSession<Long> sess =
          new MneDurableOutputSession<Long>(m_tacontext, null,
                  MneConfigHelper.DEFAULT_OUTPUT_CONFIG_PREFIX);
  MneDurableOutputValue<Long> mdvalue =
          new MneDurableOutputValue<Long>(sess);
  OutputFormat<NullWritable, MneDurableOutputValue<Long>> outputFormat =
          new MneOutputFormat<MneDurableOutputValue<Long>>();
  RecordWriter<NullWritable, MneDurableOutputValue<Long>> writer =
          outputFormat.getRecordWriter(null, m_conf, null, null);
  Long val = null;
  for (int i = 0; i < m_reccnt; ++i) {
    val = m_rand.nextLong();
    m_sum += val;
    writer.write(nada, mdvalue.of(val));
  }
  writer.close(null);
  sess.close();
}
 

@Test(enabled = true)
public void testWritePersonData() throws Exception {
  NullWritable nada = NullWritable.get();
  MneDurableOutputSession<Person<Long>> sess =
          new MneDurableOutputSession<Person<Long>>(m_tacontext, null,
                  MneConfigHelper.DEFAULT_OUTPUT_CONFIG_PREFIX);
  MneDurableOutputValue<Person<Long>> mdvalue =
          new MneDurableOutputValue<Person<Long>>(sess);
  OutputFormat<NullWritable, MneDurableOutputValue<Person<Long>>> outputFormat =
          new MneOutputFormat<MneDurableOutputValue<Person<Long>>>();
  RecordWriter<NullWritable, MneDurableOutputValue<Person<Long>>> writer =
          outputFormat.getRecordWriter(null, m_conf, null, null);
  Person<Long> person = null;
  for (int i = 0; i < m_reccnt; ++i) {
    person = sess.newDurableObjectRecord();
    person.setAge((short) m_rand.nextInt(50));
    person.setName(String.format("Name: [%s]", Utils.genRandomString()), true);
    m_sumage += person.getAge();
    writer.write(nada, mdvalue.of(person));
  }
  writer.close(null);
  sess.close();
}
 

@Test(enabled = true)
public void testWriteBufferData() throws Exception {
  NullWritable nada = NullWritable.get();
  MneDurableOutputSession<DurableBuffer<?>> sess =
      new MneDurableOutputSession<DurableBuffer<?>>(null, m_conf,
          MneConfigHelper.DEFAULT_OUTPUT_CONFIG_PREFIX);
  MneDurableOutputValue<DurableBuffer<?>> mdvalue =
      new MneDurableOutputValue<DurableBuffer<?>>(sess);
  OutputFormat<NullWritable, MneDurableOutputValue<DurableBuffer<?>>> outputFormat =
      new MneOutputFormat<MneDurableOutputValue<DurableBuffer<?>>>();
  RecordWriter<NullWritable, MneDurableOutputValue<DurableBuffer<?>>> writer =
      outputFormat.getRecordWriter(m_fs, m_conf, null, null);
  DurableBuffer<?> dbuf = null;
  Checksum cs = new CRC32();
  cs.reset();
  for (int i = 0; i < m_reccnt; ++i) {
    dbuf = genupdDurableBuffer(sess, cs);
    Assert.assertNotNull(dbuf);
    writer.write(nada, mdvalue.of(dbuf));
  }
  m_checksum = cs.getValue();
  writer.close(null);
  sess.close();
}
 

/**
 * @param jobConf Job configuration.
 * @param taskCtx Task context.
 * @param directWrite Direct write flag.
 * @param fileName File name.
 * @throws IOException In case of IO exception.
 */
HadoopV1OutputCollector(JobConf jobConf, HadoopTaskContext taskCtx, boolean directWrite,
    @Nullable String fileName, TaskAttemptID attempt) throws IOException {
    this.jobConf = jobConf;
    this.taskCtx = taskCtx;
    this.attempt = attempt;

    if (directWrite) {
        jobConf.set("mapreduce.task.attempt.id", attempt.toString());

        OutputFormat outFormat = jobConf.getOutputFormat();

        writer = outFormat.getRecordWriter(null, jobConf, fileName, Reporter.NULL);
    }
    else
        writer = null;
}
 

public RecordWriter<K, V> getRecordWriter( FileSystem fs, JobConf job, String name, Progressable progress )
  throws IOException
{
  String outputFilename = getOutputFilename( job );

  OutputFormat<K,V> of = getOutputFormat( job );

  return of.getRecordWriter( fs, job, outputFilename, progress );
  
}