Mr-Protocol:bin blossommendes$ `hadoop jar /Users/blossommendes/Desktop/Project/mahout-mrlegacy-1.0-SNAPSHOT.jar org.apache.mahout.cf.taste.hadoop.similarity.item.ItemSimilarityJob -Dmapred.input.dir=/xd/hdfsImport -Dmapred.output.dir=/xd/hdfsImport/postsResults --s SIMILARITY_LOGLIKELIHOOD --booleanData`

执行上述命令后，我得到以下异常。。我不知道为什么。。请帮我解决这个问题

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/cli2/Option
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.apache.hadoop.util.RunJar.run(RunJar.java:214)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:136)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.cli2.Option
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 4 more