Connecting to SFTP

SFTP is a network protocol that provides file operation over network .

It  runs on a secure channel.

Below is a sample code for SFTP actions.

 protected JSch jsch = null ;



    protected Session session = null ;



    protected ChannelSftp sftpChannel = null ;





    /** A convenience method for connecting and logging in */

    public boolean connectAndLogin( String host, String userName, String password, String privateKey, String publicKey ) throws IOException, JSchException

    {

        boolean success = false ;



        try

        {

            System.err.println( "Tryign to SECURELY connect " + host + " with user name " + userName + ", password: ************ " ) ;



            this.jsch = new JSch( ) ;



            // will this work?

            java.security.Security.removeProvider( "SunPKCS11-Solaris" ) ;



            JSch.setLogger( this ) ;



            if( !YClientUtils.isBlankTrim( privateKey ) && !YClientUtils.isBlankTrim( publicKey ) )

            {

                this.jsch.addIdentity( userName, privateKey.getBytes( "utf8" ), publicKey.getBytes( "utf8" ), password == null ? null : password.getBytes( "uft8" ) ) ;

            }

            else

            {

                throw new IllegalArgumentException( "Private and public keys must not be null" ) ;

            }



            this.session = this.jsch.getSession( userName, host ) ;



            this.session.setConfig( "StrictHostKeyChecking", "no" ) ;



            this.session.setConfig( "PreferredAuthentications", "publickey" ) ;

            this.session.setTimeout( 120000 ) ;

            

            this.session.connect( ) ;



            Channel channel = this.session.openChannel( "sftp" ) ;

            channel.connect( ) ;



            this.sftpChannel = ( ChannelSftp )channel ;

            success = true ;

        }

        catch( IOException e )

        {

            e.printStackTrace( ) ;

            success = false ;

            throw e ;

        }

        catch( JSchException e )

        {

            e.printStackTrace( ) ;

            success = false ;

            throw e ;

        }

        finally

        {

            System.err.println( "SECURELY connect status  " + host + " with user name " + userName + " :" + ( success ? "SUCCESS" : "FAIL" ) ) ;

        }



        return success ;

    }



    public void close( )

    {

        if( this.sftpChannel != null )

        {

            this.sftpChannel.exit( ) ;

        }



        if( this.session != null )

        {

            this.session.disconnect( ) ;

        }

    }



    public boolean downloadFile( String remoteFile, String localFile )

    {

        try

        {

            this.sftpChannel.get( remoteFile, localFile ) ;



            return true ;

        }

        catch( Exception e )

        {

            e.printStackTrace( ) ;



            return false ;

        }

    }



    public boolean uploadFile( String localFile, String remoteFile )

    {

        try

        {

            this.sftpChannel.put( localFile, remoteFile ) ;



            return true ;

        }

        catch( Exception e )

        {

            e.printStackTrace( ) ;



            return false ;

        }

    }



    public boolean deleteFile( String remoteFile, int tryCount ) throws IOException

    {

        int count = 0 ;



        while( count++ < tryCount )

        {

            try

            {

                this.sftpChannel.rm( remoteFile ) ;



                return true ;

            }

            catch( Exception e )

            {

                System.err.println( "Trial " + count ) ;

                e.printStackTrace( ) ;

            }

        }



        return false ;

    }