hadoop java tutorial

This article describes the configuration method for using the HDFs Java API.1, first solve the dependence, pomDependency> groupId>Org.apache.hadoopgroupId> Artifactid>Hadoop-clientArtifactid> version>2.7.2version> Scope>ProvidedScope> Dependency>2, configuration files, storage HDFs cluster configuration information, basically from Core-site.xml and Hdfs-sit

Hadoop reading Notes (i) Introduction to Hadoop: http://blog.csdn.net/caicongyang/article/details/39898629Hadoop Reading notes (ii) the shell operation of HDFs :http://blog.csdn.net/caicongyang/article/details/41253927JAVA URL Operation HDFsOperatebyurl.javaPackage Hdfs;import Java.io.inputstream;import Java.net.url;import org.apache.hadoop.fs.FsUrlStreamHandlerFactory; Import Org.apache.hadoop.io.ioutils;p

classes that are used by the entire jobJob.setjarbyclass (Wcrunner.class);Job.setmapperclass (Wcmapper.class);Job.setreducerclass (Wcreducer.class);Map output Data kv typeJob.setmapoutputkeyclass (Text.class);Job.setmapoutputvalueclass (Longwritable.class);Reduce output data kv typeJob.setoutputkeyclass (Text.class);Job.setoutputvalueclass (Longwritable.class);Path to execute input dataFileinputformat.setinputpaths (Job, New Path ("/wordcount/inpput"));Path to execute output dataFileoutputforma

Configuration file m103 Replace with the HDFs service address.To use the Java client to access the file on the HDFs, have to say is the configuration file Hadoop-0.20.2/conf/core-site.xml, originally I was here to eat a big loss, so I am not even hdfs, file can not be created, read. Configuration item: Hadoop.tmp.dir represents the directory location on the named node where the metadata resid

Running the Hadoop routine in Java error: Org.apache.hadoop.fs.LocalFileSystem cannot be cast to Org.apache. The code is as follows: PackageCom.pcitc.hadoop;Importjava.io.IOException;Importorg.apache.hadoop.conf.Configuration;ImportOrg.apache.hadoop.fs.FileSystem;ImportOrg.apache.hadoop.hdfs.DistributedFileSystem;ImportOrg.apache.hadoop.hdfs.protocol.DatanodeInfo;/*** Get all node names on the HDFs cluster

When connecting to a Hadoop cluster through the Java API, if the cluster supports HA mode, it can be set up to automatically switch to the active master node as follows. Wherein, clustername can be arbitrarily specified, with the cluster configuration independent, Dfs.ha.namenodes.ClusterName can also arbitrarily specify the name, there are several master write a few, followed by the corresponding settings

")); SYSTEM.OUT.PRINTLN (flag); @Test public void Testupload () throws IllegalArgumentException, ioexception{fsdataoutputstream out = FS . Create (New Path ("/words.txt")); FileInputStream in = new FileInputStream (New File ("E:/w.txt")); Ioutils.copybytes (in, out, 2048, true); public static void Main (string[] args) throws Exception {Configuration conf = new Configuration (); Conf.set ("Fs.defaultfs", "hdfs://123.206.xxx.xxx:9000"); Conf.set (

The client needs to specify the NS name, node configuration, Configuredfailoverproxyprovider and other information.code example:Package Cn.itacst.hadoop.hdfs;import Java.io.fileinputstream;import java.io.inputstream;import Java.io.outputstream;import Java.net.uri;import Org.apache.hadoop.conf.configuration;import Org.apache.hadoop.fs.filesystem;import Org.apache.hadoop.fs.path;import org.apache.hadoop.io.IOUtils; Public classHdfs_ha { Public Static voidMain (string[] args) throws Exception {Conf

CD hadoop-2.4.1/lib/nativeFile libhadoop.so.1.0.0 to view your own version of HadoopView dependent libraries with the LDD commandLDD libhadoop.so.1.0.0LDD--version native version of GCChttp://blog.csdn.net/l1028386804/article/details/51538611Should be due to the GCC version of the problem, this will be compiled for a long time, so the solution is to comment out the log4j inside, or in the beginning of the installation of Linux after the upgrade and gl

to be closed manually, System.out is also an output stream, and if true, it will not output theIoutils.copybytes (in, System.out, 1024,false); In.close (); }Delete a file or folder/**Delete a file or folder * True: Indicates whether to delete recursively, if it is a file, here is True,false is indifferent, * folder must be true, otherwise error *@throwsurisyntaxexception*/ Public Static voidDelete ()throwsIOException, urisyntaxexception {FileSystem FileSystem=Getfilesystem (); BooleanisD

(Text.class); Job.setmapoutputvalueclass (Longwritable.class); Job.setreducerclass (Jreducer.class); Job.setoutputkeyclass (Text.class); Job.setoutputvalueclass ( Longwritable.class); Fileoutputformat.setoutputpath (Job, Outpath); Job.setoutputformat (textoutputformat.class);// Use Jobclient.runjob instead of job.waitForCompletionJobClient.runJob (job);}}Can seeIn fact, the old version of the API is not very different, just a few classes replaced itNote that the old version of the API class is

Parameters required for configuration:Configuration conf = new Configuration();conf.set("fs.defaultFS", "hdfs://hadoop2cluster");conf.set("dfs.nameservices", "hadoop2cluster");conf.set("dfs.ha.namenodes.hadoop2cluster", "nn1,nn2");conf.set("dfs.namenode.rpc-address.hadoop2cluster.nn1", "10.0.1.165:8020");conf.set("dfs.namenode.rpc-address.hadoop2cluster.nn2", "10.0.1.166:8020");conf.set("dfs.client.failover.proxy.provider.hadoop2cluster", "org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFai

The Hadoop installation in this article is based on the Hortonworks RPMs installation Documents See: Http://docs.hortonworks.com/CURRENT/index.htm Http://www.oracle.com/technetwork/java/javase/downloads/jdk-6u31-download-1501634.html Download Java jdk-6u31-linux-x64.bin #Java settings chmod U+x/home/jdk-6u31-linux

(i) Download installation1. Download VISUALVMDownload on official website, with Mac version2, tools-Plug-ins, select the plug of interest to installAt this point, if there is a local running Java process, then the local there is already able to monitor the analysis(ii) Remote server configuration1, in any directory to establish the file Jstatd.all.policy, the contents are as follows:Grant CodeBase "file:${java.home}/. /lib/tools.jar "{Permission java.