关于CDH中hadoop-mapreduce-examples.jar中的例子如何使用？？

我看了下这个hadoop-mapreduce-examples.jar文件里面有很多class文件。应该是针对不同的示例的，如单词统计、求圆周率……
但是不知道 这个示例的使用方法。有这些示例运行所需要的参数说明吗？
该jar文件的内容如下：
[cdhfive@datanode1 ~]$ jar -tf hadoop-mapreduce-examples-2.6.0-cdh5.4.5.jar
META-INF/
META-INF/MANIFEST.MF
org/
org/apache/
org/apache/hadoop/
org/apache/hadoop/examples/
org/apache/hadoop/examples/dancing/
org/apache/hadoop/examples/terasort/
org/apache/hadoop/examples/pi/
org/apache/hadoop/examples/pi/math/
org/apache/hadoop/examples/RandomTextWriter.class
org/apache/hadoop/examples/DBCountPageView$PageviewRecord.class
org/apache/hadoop/examples/DBCountPageView.class
org/apache/hadoop/examples/AggregateWordCount$WordCountPlugInClass.class
org/apache/hadoop/examples/RandomTextWriter$RandomTextMapper.class
org/apache/hadoop/examples/RandomWriter$RandomMapper.class
org/apache/hadoop/examples/SecondarySort$Reduce.class
org/apache/hadoop/examples/DBCountPageView$PageviewReducer.class
org/apache/hadoop/examples/QuasiMonteCarlo.class
org/apache/hadoop/examples/SecondarySort$FirstPartitioner.class
org/apache/hadoop/examples/WordStandardDeviation$WordStandardDeviationReducer.class
org/apache/hadoop/examples/RandomWriter$Counters.class
org/apache/hadoop/examples/WordMedian.class
org/apache/hadoop/examples/QuasiMonteCarlo$HaltonSequence.class
org/apache/hadoop/examples/SecondarySort$MapClass.class
org/apache/hadoop/examples/SecondarySort$IntPair.class
org/apache/hadoop/examples/WordMedian$WordMedianReducer.class
org/apache/hadoop/examples/WordCount$TokenizerMapper.class
org/apache/hadoop/examples/MultiFileWordCount$MyInputFormat.class
org/apache/hadoop/examples/SecondarySort.class
org/apache/hadoop/examples/WordMedian$WordMedianMapper.class
org/apache/hadoop/examples/SecondarySort$FirstGroupingComparator.class
org/apache/hadoop/examples/dancing/Sudoku$SolutionPrinter.class
org/apache/hadoop/examples/dancing/Pentomino$SolutionCategory.class
org/apache/hadoop/examples/dancing/Sudoku$CellConstraint.class
org/apache/hadoop/examples/dancing/OneSidedPentomino.class
org/apache/hadoop/examples/dancing/DistributedPentomino$PentMap$SolutionCatcher.class
org/apache/hadoop/examples/dancing/Pentomino$SolutionPrinter.class
org/apache/hadoop/examples/dancing/DancingLinks$ColumnHeader.class
org/apache/hadoop/examples/dancing/Pentomino.class
org/apache/hadoop/examples/dancing/Sudoku$ColumnName.class
org/apache/hadoop/examples/dancing/DistributedPentomino$PentMap.class

格式都是差不多的
hadoop jar jar包 输入路径 输出路径

hadoop jar /usr/hadoop/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.2.0.jar wordcount /data/wordcount /output/wordcount