HDFS API Learning: A few common APIs

1.hadoop-1.2.1 API Documentation: http://hadoop.apache.org/docs/r1.2.1/api/

2. Several APIs:

　　create(Path f): Opens an fsdataoutputstream at the indicated Path.

　　copyFromLocalFile(Path src, Path dst): The src file is on the local disk.

　　create(Path f): Opens an fsdataoutputstream at the indicated Path.

　　booleanexists(Path f): Check if exists.

　　get(URI uri, Configuration conf):Returns the FileSystem for this URI‘s scheme and authority.

　　listStatus(Path f): List the statuses of the files/directories in the given path if the path is a directory.

　　mkdirs(Path f): Call with mkdirs(Path, FsPermission) default permission.

　　rename(Path src, Path dst): Renames path src to path DST.

3. Code implementation:

Importjava.io.IOException;ImportJava.net.URI;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; Public classTesthdfs {StaticString HDFs = "hdfs://localhost:9000"; StaticConfiguration conf =NewConfiguration ();  Public Static voidCreateFolder ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path Path=NewPath ("/test");        Fs.mkdirs (path);    Fs.close (); }     Public Static voidCreateFile ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path Path=NewPath ("/test/test3.txt"); Fsdataoutputstream out=fs.create (path); Out.write ("Hello Hadoop.". GetBytes ()); }     Public Static voidRenameFile ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path Path=NewPath ("/test/test1.txt"); Path NewPath=NewPath ("/test/test2.txt");    System.out.println (Fs.rename (path, NewPath)); }     Public Static voidUploadfiletohdfs ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path src=NewPath ("/home/ares/test.txt"); Path DST=NewPath ("/test");    Fs.copyfromlocalfile (SRC, DST); }     Public Static voidListFile ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path Path=NewPath ("/test"); filestatus[] Files=fs.liststatus (path);  for(Filestatus file:files) {System.out.println (File.getpath (). toString ()); }    }     Public Static voidDeletefileonhdfs ()throwsIOException {FileSystem fs=Filesystem.get (Uri.create (HDFS), conf); Path Path=NewPath ("/test/test2.txt"); BooleanIsexists =fs.exists (path); if(isexists) {fs.delete (path, isexists); System.out.println ("File is deleted."); } Else{System.out.println ("File is exist."); }    }     Public Static voidMain (string[] args)throwsIOException {//CreateFolder (); //CreateFile (); //RenameFile (); //Uploadfiletohdfs (); //listfile ();Deletefileonhdfs (); }}

HDFS API Learning: A few common APIs