我想知道这个错误的根本原因。当我在hadoop-2.6.0中开始运行传统的字数计算程序时，会生成以下异常。您的建议将不胜感激。

16/03/16 11:21:40 INFO mapreduce.Job:  map 0% reduce 0%
    16/03/16 11:21:40 INFO mapreduce.Job: Job job_1458107299826_0002 failed with state FAILED due to: Application application_1458107299826_0002 failed 2 times due to Error launching appattempt_1458107299826_0002_000002. Got exception: java.net.ConnectException: Call From abc-OptiPlex-3020/127.0.1.1 to abc-OptiPlex-3020:52890 failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

我的/etc/hosts文件如下：来自主系统

127.0.0.1   localhost
127.0.1.1   abc-OptiPlex-3020

# The following lines are desirable for IPv6 capable hosts

::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
192.168.12.106  HadoopMaster
192.168.12.105  HadoopSlave1