Chain.java 文件源码

protected static void setMapperConf(boolean isMap, Configuration jobConf,
    Class<?> inputKeyClass, Class<?> inputValueClass,
    Class<?> outputKeyClass, Class<?> outputValueClass,
    Configuration mapperConf, int index, String prefix) {
  // if the Mapper does not have a configuration, create an empty one
  if (mapperConf == null) {
    // using a Configuration without defaults to make it lightweight.
    // still the chain's conf may have all defaults and this conf is
    // overlapped to the chain configuration one.
    mapperConf = new Configuration(true);
  }

  // store the input/output classes of the mapper in the mapper conf
  mapperConf.setClass(MAPPER_INPUT_KEY_CLASS, inputKeyClass, Object.class);
  mapperConf
      .setClass(MAPPER_INPUT_VALUE_CLASS, inputValueClass, Object.class);
  mapperConf.setClass(MAPPER_OUTPUT_KEY_CLASS, outputKeyClass, Object.class);
  mapperConf.setClass(MAPPER_OUTPUT_VALUE_CLASS, outputValueClass,
      Object.class);
  // serialize the mapper configuration in the chain configuration.
  Stringifier<Configuration> stringifier = 
    new DefaultStringifier<Configuration>(jobConf, Configuration.class);
  try {
    jobConf.set(prefix + CHAIN_MAPPER_CONFIG + index, stringifier
        .toString(new Configuration(mapperConf)));
  } catch (IOException ioEx) {
    throw new RuntimeException(ioEx);
  }

  // increment the chain counter
  jobConf.setInt(prefix + CHAIN_MAPPER_SIZE, index + 1);
}