Hadoop HDFS Tools

Hadoop HDFS Tools

 PackageCN.BUAA;ImportJava.io.ByteArrayOutputStream;ImportJava.io.IOException;ImportJava.io.InputStream;ImportOrg.apache.hadoop.conf.Configuration;ImportOrg.apache.hadoop.fs.FSDataOutputStream;ImportOrg.apache.hadoop.fs.FileStatus;ImportOrg.apache.hadoop.fs.FileSystem;ImportOrg.apache.hadoop.fs.Path;ImportOrg.apache.hadoop.fs.RemoteIterator;ImportOrg.apache.hadoop.io.IOUtils;/ * * @author LZXYZQ * HDFs Some common commands, can refer to the Hadoop API FileSystem */ Public  class hdfstools {     Public Hdfstools(){ }//Determine if a file exists in the HDFs file system     Public Static Boolean exists(Configuration config,string Path)throwsioexception{//File system objects are formed according to profile informationFileSystem fs = filesystem.get (config);returnFs.exists (Newpath);//Convert file path to path        //Determine if the file already exists}//give a filename and content, we create the file in HDFs     Public Static void CreateFile(Configuration config,string Path,byte[] buf)throwsioexception{//config-->fs-->fos-->write-->closeFileSystem fs = filesystem.get (config); Path path2 =NewPath (path);        Fsdataoutputstream fos = fs.create (path2);        Fos.write (BUF);        Fos.close ();    Fs.close (); } Public Static void CreateFile(Configuration config,string path,string info)throwsioexception{The difference between//and the above function is that the above function passes in the BUF data, and the following string is passed inCreateFile (Config,path,info.getbytes ()); }//Copy a file on HDFs to another location on HDFs     Public Static void copyfromlocal(Configuration config,string path1,string path2)throwsioexception{FileSystem fs = filesystem.get (config); Path P1 =NewPath (path1); Path P2 =NewPath (path2); Fs.copyfromlocalfile (true,true, p1, p2);//delsrc, overwrite, SRCs, DSTFs.close (); }//Delete one of the files on HDFs     Public Static Boolean DeleteFile(Configuration config,string Path,BooleanMarkthrowsioexception{//config-->fs-->delete-->close--> returnFileSystem fs = filesystem.get (config); Path P1 =NewPath (path);BooleanFlag = Fs.delete (P1, Mark); Fs.close ();returnFlag } Public Static Boolean DeleteFile(Configuration config,string Path)throwsioexception{returnDeleteFile (Config,path,true); }//Modify the file name on HDFs string-->path-->fs.renamefile     Public Static Boolean RenameFile(Configuration config,string path1,strign path2) {//config-->fs-->delete-->close--> returnFileSystem fs = filesystem.get (config); Path oldname =NewPath (path1); Path NewName =NewPath (path2);BooleanFlag = Fs.rename (Oldname, newName); Fs.close ();returnFlag }//Create a directory on HDFs     Public Static Boolean MakeDir(Configuration config,string Path)throwsioexception{FileSystem fs = filesystem.get (config); Path name =NewPath (path);BooleanFlag = fs.mkdirs (name); Fs.close ();returnFlag } Public StaticRemoteiterator<locatedfilestatus>Listfiles(Configuration config,string Path,BooleanMarkthrowsioexception{FileSystem fs = filesystem.get (config); remoteiterator<locatedfilestatus> r1 = Fs.listfiles (NewPath (path), Mark);returnR1; } Public StaticRemoteiterator<locatedfilestatus>Listfiles(Configuration config,string Path)throwsioexception{returnListfiles (Config,path,false); } Public StaticFilestatus[]Liststatus(Configuration config, String path)throwsioexception{FileSystem fs = filesystem.get (config); Path path1 =NewPath (path);        Filestatus status[] = Fs.liststatus (path1); Fs.close ();returnStatus }//Read file contents, return string     Public StaticStringReadFile(Configuration config,string Path)throwsioexception{FileSystem fs = filesystem.get (config);        String temp; InputStream is =NULL;//input streamBytearrayoutputstream BAOs =NULL;//output streamPath p =NewPath (path);Try{is =fs.open (p);//Open input stream            //input stream output stream dockingBAOs =NewBytearrayoutputstream (Is.available ());//Import the contents of the input stream into the output streamIoutils.copybytes (is, BAOs, config); temp = baos.tostring ();//Turn the contents of the output stream into a string}finally{//Turn off the input and output stream and file systemIoutils.closestream (IS);            Ioutils.closestream (BAOs);        Fs.close (); }returnTemp } Public Static Boolean CreateDictionary(Configuration config,string Path)throwsioexception{FileSystem fs = filesystem.get (config); Path p =NewPath (path);BooleanFlag = Fs.mkdirs (p); Fs.close ();returnFlag } Public Static void Main(string[] args)throwsioexception{Configuration config =NewConfiguration (); String dir ="/test";BooleanFlag = exists (Config,dir);if(flag==true) {System.out.println ("Sorry It ' s exists"); }Else{flag = CreateDictionary (Config,dir);if(flag==true) {System.out.println ("created successfully"); }Else{System.out.println ("Create failed"); }} String info ="Beihang University!" "; String FileName = dir+"/buaa.txt";        CreateFile (Config,filename,info); System.out.println ("Create file succeeded");        String message = ReadFile (config,filename);        SYSTEM.OUT.PRINTLN (message); Filestatus all[] = liststatus (config,"/"); for(intI=0; i<all.length;i++) {System.out.println (all[i]);        } FileSystem fs = filesystem.get (config); Remoteiterator ri = listfiles (config,"/",true); while(Ri.hasnext ())            {String str = Ri.next (). toString ();        System.out.println (str);        } deletefile (Config,filename); System.out.println (filename+"is deleted"); }}

Hadoop HDFS Tools