java - Java客户端连接远程Hadoop机器错误

Question

我正在编写一个Java客户端程序，该程序可以与远程hadoop群集进行交互并打印所有正在运行的作业。

我的本地计算机能够ping运行hadoop的远程计算机。
我尝试下面的代码，并坚持使用参数。我在哪里可以得到这些配置参数值

Configuration conf = new Configuration();
// this should be like defined in your mapred-site.xml
conf.set("mapred.job.tracker", "Hadoopmaster:54311"); 
// like defined in hdfs-site.xml
conf.set("fs.default.name", "hdfs://namenode.com:9000");

System.out.println("got configuration : "+conf);
InetSocketAddress jobtracker = new InetSocketAddress("jobtracker.mapredhost.myhost", 8021);
JobClient jobClient = new JobClient(jobtracker, conf);
JobStatus[] jobs = jobClient.jobsToComplete();

        for (int i = 0; i < jobs.length; i++) {
            JobStatus js = jobs[i];
            if (js.getRunState() == JobStatus.RUNNING) {
                JobID jobId = js.getJobID();
                System.out.println(jobId);
            }
        }
    }

map-red.xml

<property>
  <name>mapred.job.tracker</name>
  <value>Hadoopmaster:54311</value>
  <description>test </description>
</property>

core-site.xml

<property>
  <name>fs.default.name</name>
  <value>hdfs://Hadoopmaster:54310</value>
  <description>test.</description>
</property>

Answer 1

在提供的样本中，配置属性与客户端和群集fs.default.name不匹配
为了通过Java连接到远程hadoop集群，我做了以下代码:

public static void main(String a[]) {
     UserGroupInformation ugi
     = UserGroupInformation.createRemoteUser("root");

     try {


        ugi.doAs(new PrivilegedExceptionAction<Void>() {

            public Void run() throws Exception {

                conf = new Configuration();
                    //fs.default.name should match the corresponding value 
                    // in your core-site.xml in hadoop cluster
                conf.set("fs.default.name","hdfs://hostname:9000");
                conf.set("hadoop.job.ugi", "root");
                    // in case you are running mapreduce job , need to set
                    // 'mapred.job.tracker' as you did
                    conf.set("mapred.job.tracker", "hostname:port"); 

                 // do your code here. 

                return null;
            }
        });

    } catch (Exception e) {
        e.printStackTrace();
    }

}

如果需要默认值，请检查:

http://hadoop.apache.org/docs/current2/hadoop-project-dist/hadoop-common/core-default.xml

和

http://hadoop.apache.org/docs/stable/hadoop-mapreduce-client/hadoop-mapreduce-client-core/mapred-default.xml