Error accessing Hadoop cluster: Access denied for user Administrator. Superuser privilege is required

After the Hadoop cluster is set up, the Hadoop cluster is accessed locally via the Java API, as follows (see all node name information on the Hadoop cluster)

Import org.apache.hadoop.conf.Configuration;
Import Org.apache.hadoop.fs.FileSystem;
Import Org.apache.hadoop.hdfs.DistributedFileSystem;
Import Org.apache.hadoop.hdfs.protocol.DatanodeInfo;

Import java.io.IOException;
Import Java.net.URI;

public class Accesshdfs {public
    static void Main (string[] args) throws IOException {
        Configuration conf=new confi Guration ();
        FileSystem fs= Filesystem.get (uri.create ("Hdfs://your-ip:9000/file-path"), conf);
        Distributedfilesystem DFS = (distributedfilesystem) fs;
        datanodeinfo[] Datanodestats = Dfs.getdatanodestats ();

        for (int i=0; i<datanodestats.length; i++) {
            System.out.println ("Datanode_" + i + "_node:" + datanodestats[i]. GetHostName ());}}

The access denied for user Administrator appears. Superuser privilege is required error message:

Exception in thread "main" org.apache.hadoop.ipc.RemoteException (org.apache.hadoop.security.AccessControlException ): Access denied for user Administrator. Superuser privilege is required at Org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkSuperuserPrivilege (Fspermissionchecker.java :) at Org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkSuperuserPrivilege (fsnamesystem.java:4484) at Org.apache.hadoop.hdfs.server.namenode.FSNamesystem.datanodeReport (fsnamesystem.java:4137) at Org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getDatanodeReport (namenoderpcserver.java:1151) at Org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.getDatanodeReport ( clientnamenodeprotocolserversidetranslatorpb.java:728) at Org.apache.hadoop.hdfs.protocol.proto.clientnamenodeprotocolprotos$clientnamenodeprotocol$2.callblockingmethod (Clientnamenodeprotocolprotos.java) at Org.apache.hadoop.ipc.protobufrpcengine$server$protobufrpcinvoker.call ( Protobufrpcengine.java:503) at Org.apache.hadoop.ipc.rpc$server.call (rpc.java:989) at org.apache.hadoop.ipc.server$ Rpccall.run (server.java:868) at Org.apache.hadoop.ipc.server$rpccall.run (server.java:814) at
	Java.security.AccessController.doPrivileged (Native method) at Javax.security.auth.Subject.doAs (subject.java:422) At Org.apache.hadoop.security.UserGroupInformation.doAs (usergroupinformation.java:1886) at Org.apache.hadoop.ipc.server$handler.run (server.java:2603) at Org.apache.hadoop.ipc.Client.call (client.java:1470 ) at Org.apache.hadoop.ipc.Client.call (client.java:1401) at Org.apache.hadoop.ipc.protobufrpcengine$invoker.invoke (protobufrpcengine.java:232) at Com.sun.proxy. $Proxy 9.getDatanodeReport (Unknown Source) at Org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getDatanodeReport ( clientnamenodeprotocoltranslatorpb.java:607) at Sun.reflect.NativeMethodAccessorImpl.invoke0 (Native method) at Sun.reflect.NativeMethodAccessorImpl.invoke (Nativemethodaccessorimpl.java:62) at Sun.reflect.DelegatingMethodAccessorImpl.invoke (delegatingmethodaccessorimpl.java:43) at Java.lang.reflect.Method.invoke (method.java:498) at Org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod (retryinvocationhandler.java:187) at Org.apache.hadoop.io.retry.RetryInvocationHandler.invoke (retryinvocationhandler.java:102) at com.sun.proxy.$
	Proxy10.getdatanodereport (Unknown Source) at Org.apache.hadoop.hdfs.DFSClient.datanodeReport (dfsclient.java:2390) At Org.apache.hadoop.hdfs.DistributedFileSystem.getDataNodeStats (distributedfilesystem.java:1009) at Org.apache.hadoop.hdfs.DistributedFileSystem.getDataNodeStats (distributedfilesystem.java:1003) at Com.fhpt.AccessHdfs.main (accesshdfs.java:28)

The reason for this error is that the administrator user does not have permission to refer to the http://blog.sina.com.cn/s/blog_e699b42b0102xfnd.html or to use the following simple method.

Add the following information to your code, where "root" is the user name with access to the Hadoop cluster

System.setproperty ("Hadoop_user_name", "root");