What are the basic commands commonly used in HDFS
This article mainly introduces what the basic common commands of HDFS are, which can be used for reference by interested friends. I hope you can learn a lot after reading this article.
one。 Create a HDFS file:
Public class Test4CreateFile {/ * create the HDFS file: * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") Byte [] buff = "Hello Hadoop HDFS" .getBytes (); FileSystem fs = FileSystem.get (uri, conf); Path dfs = new Path ("hdfs://192.168.226.129:9000/studyhadoop"); FSDataOutputStream outputStream = fs.create (dfs) OutputStream.write (buff,0,buff.length); FileStatus files [] = fs.listStatus (dfs); for (FileStatus file:files) {System.out.println ("file:" + file.getPath ()) } catch (Exception e) {e.printStackTrace ();}
Two: delete the HDFS file
Public class Test5DeleteFile {/ * Delete the HDFS file: * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") FileSystem fs = FileSystem.get (uri, conf); Path delef = new Path ("hdfs://192.168.226.129:9000/testhadoop1"); boolean isDeleted = fs.delete (delef, false); System.out.println ("isDelete:" + isDeleted) } catch (Exception e) {e.printStackTrace ();}
Three: create a HDFS directory
Create a directory file under public class Test9Mkdir {/ * HDFS * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") FileSystem fs = FileSystem.get (uri, conf); Path dfs = new Path ("hdfs://192.168.226.129:9000/testhadoop"); boolean isMkdirs = fs.mkdirs (dfs); if (isMkdirs) {System.out.println ("Make Dir Successful!") } else {System.out.println ("Make Dir Failure!");} fs.close ();} catch (IllegalArgumentException e) {e.printStackTrace () } catch (URISyntaxException e) {e.printStackTrace ();} catch (IOException e) {e.printStackTrace ();}
Four: rename the HDFS file
Public class Test2Rename {/ * rename the HDFS file: * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") FileSystem fs = FileSystem.get (uri,conf); Path oldpath = new Path ("hdfs://192.168.226.129:9000/testhadoop"); Path newpath = new Path ("hdfs://192.168.226.129:9000/testhadoop1") / / determine whether the file exists boolean isExists = fs.exists (oldpath); System.out.println ("isExists:" + isExists); / / rename the file fs.rename (oldpath, newpath) IsExists = fs.exists (newpath); System.out.println ("newpathisExists:" + isExists);} catch (Exception e) {e.printStackTrace ();}
5: upload local files to HDFS
Public class Test3CopyFile {/ * upload local files to HDFS * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") FileSystem fs = FileSystem.get (uri, conf); Path src = new Path ("F:\\ 04-HadoopStudy\\ mapreduce.txt"); Path dst = new Path ("hdfs://192.168.226.129:9000/rootdir"); fs.copyFromLocalFile (src, dst) System.out.println ("Upload" + conf.get ("fs.default.name")); FileStatus files [] = fs.listStatus (dst); for (FileStatus file:files) {System.out.println (file.getPath ()) } catch (Exception e) {e.printStackTrace ();}
six。 Download files from HDFS to local
Public class Test10CopyToFile {/ * download files from HDFS to local * * / public static void main (String [] args) {try {Configuration conf = new Configuration (); URI uri = new URI ("hdfs://192.168.226.129:9000") FileSystem fs = FileSystem.get (uri, conf); Path src = new Path ("F:\"); Path dst = new Path ("hdfs://192.168.226.129:9000/studyhadoop"); fs.copyToLocalFile (dst, src) System.out.println ("DownLoad" + conf.get ("fs.default.name")); FileStatus files [] = fs.listStatus (dst); for (FileStatus file:files) {System.out.println (file.getPath ()) } catch (IllegalArgumentException e) {e.printStackTrace ();} catch (FileNotFoundException e) {e.printStackTrace ();} catch (URISyntaxException e) {e.printStackTrace () } catch (IOException e) {e.printStackTrace ();} Thank you for reading this article carefully. I hope the article "what are the basic common commands of HDFS" shared by the editor will be helpful to you. At the same time, I also hope that you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!
