org.apache.hadoop.mapred.lib.aggregate
Class UserDefinedValueAggregatorDescriptor

java.lang.Object
  org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor
      org.apache.hadoop.mapred.lib.aggregate.UserDefinedValueAggregatorDescriptor

All Implemented Interfaces:

ValueAggregatorDescriptor

@InterfaceAudience.Public
@InterfaceStability.Stable
public class UserDefinedValueAggregatorDescriptor
extends UserDefinedValueAggregatorDescriptor
implements ValueAggregatorDescriptor

This class implements a wrapper for a user defined value aggregator descriptor. It serves two functions: One is to create an object of ValueAggregatorDescriptor from the name of a user defined class that may be dynamically loaded. The other is to delegate invocations of generateKeyValPairs function to the created object.

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor

theAggregatorDescriptor

Fields inherited from interface org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorDescriptor

ONE, TYPE_SEPARATOR

Constructor Summary

UserDefinedValueAggregatorDescriptor(String className, JobConf job)

Method Summary

void	configure(JobConf job) Do nothing.
static Object	createInstance(String className) Create an instance of the given class

Methods inherited from class org.apache.hadoop.mapreduce.lib.aggregate.UserDefinedValueAggregatorDescriptor

configure, generateKeyValPairs, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorDescriptor

configure, generateKeyValPairs

Constructor Detail

UserDefinedValueAggregatorDescriptor

public UserDefinedValueAggregatorDescriptor(String className,
                                            JobConf job)

Parameters:

className - the class name of the user defined descriptor class

job - a configure object used for decriptor configuration

Method Detail

createInstance

public static Object createInstance(String className)

Create an instance of the given class

Parameters:

className - the name of the class

Returns:

a dynamically created instance of the given class

configure

public void configure(JobConf job)

Do nothing.

Parameters:

job - a JobConf object that may contain the information that can be used to configure the object.