org.apache.hadoop.examples

类 AggregateWordCount.WordCountPlugInClass

java.lang.Object

org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor

org.apache.hadoop.examples.AggregateWordCount.WordCountPlugInClass

所有已实现的接口:

ValueAggregatorDescriptor

封闭类:

AggregateWordCount

public static class AggregateWordCount.WordCountPlugInClass
extends ValueAggregatorBaseDescriptor

字段概要

从类继承的字段 org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor

DOUBLE_VALUE_SUM, inputFile, LONG_VALUE_MAX, LONG_VALUE_MIN, LONG_VALUE_SUM, STRING_VALUE_MAX, STRING_VALUE_MIN, UNIQ_VALUE_COUNT, VALUE_HISTOGRAM

从接口继承的字段 org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorDescriptor

ONE, TYPE_SEPARATOR

构造器概要

构造器

构造器和说明
AggregateWordCount.WordCountPlugInClass()

方法概要

方法

限定符和类型	方法和说明
ArrayList<Map.Entry<Text,Text>>	generateKeyValPairs(Object key, Object val) Generate 1 or 2 aggregation-id/value pairs for the given key/value pair.

从类继承的方法 org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor

configure, generateEntry, generateValueAggregator

从类继承的方法 java.lang.Object

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

构造器详细资料

AggregateWordCount.WordCountPlugInClass

public AggregateWordCount.WordCountPlugInClass()

方法详细资料

generateKeyValPairs

public ArrayList<Map.Entry<Text,Text>> generateKeyValPairs(Object key,
                                                  Object val)

从类复制的说明: ValueAggregatorBaseDescriptor

Generate 1 or 2 aggregation-id/value pairs for the given key/value pair. The first id will be of type LONG_VALUE_SUM, with "record_count" as its aggregation id. If the input is a file split, the second id of the same type will be generated too, with the file name as its aggregation id. This achieves the behavior of counting the total number of records in the input data, and the number of records in each input file.

指定者:

generateKeyValPairs 在接口中 ValueAggregatorDescriptor

覆盖:

generateKeyValPairs 在类中 ValueAggregatorBaseDescriptor

参数:

key - input key

val - input value

返回:

a list of aggregation id/value pairs. An aggregation id encodes an aggregation type which is used to guide the way to aggregate the value in the reduce/combiner phrase of an Aggregate based job.