我对oozie很陌生，正在尝试用它来编写oozie工作流 CDH4.1.1 . 因此，我启动了oozie服务，然后使用以下命令检查状态： sudo service oozie status 我得到消息： running 然后我尝试了这个命令来检查状态： oozie admin --oozie http://localhost:11000/oozie status 我得到了以下例外：

java.lang.NullPointerException
    at java.io.Writer.write(Writer.java:140)
    at org.apache.oozie.client.AuthOozieClient.writeAuthToken(AuthOozieClient.java:182)
    at org.apache.oozie.client.AuthOozieClient.createConnection(AuthOozieClient.java:137)
    at org.apache.oozie.client.OozieClient.validateWSVersion(OozieClient.java:243)
    at org.apache.oozie.client.OozieClient.createURL(OozieClient.java:344)
    at org.apache.oozie.client.OozieClient.access$000(OozieClient.java:76)
    at org.apache.oozie.client.OozieClient$ClientCallable.call(OozieClient.java:410)
    at org.apache.oozie.client.OozieClient.getSystemMode(OozieClient.java:1299)
    at org.apache.oozie.cli.OozieCLI.adminCommand(OozieCLI.java:1323)
    at org.apache.oozie.cli.OozieCLI.processCommand(OozieCLI.java:499)
    at org.apache.oozie.cli.OozieCLI.run(OozieCLI.java:466)
    at org.apache.oozie.cli.OozieCLI.main(OozieCLI.java:176)
null

读取异常堆栈时，我无法找出此异常的原因。请让我知道为什么我得到这个例外，以及如何解决这个问题。