How to retrieve a file from a server via SFTP?

Question

I\'m trying to retrieve a file from a server using SFTP (as opposed to FTPS) using Java. How can I do this?

Answer 1

Apache Commons SFTP library

Common java properties file for all the examples

serverAddress=111.222.333.444

userId=myUserId

password=myPassword

remoteDirectory=products/

localDirectory=import/

Upload file to remote server using SFTP

import java.io.File;
import java.io.FileInputStream;
import java.util.Properties;

import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.Selectors;
import org.apache.commons.vfs2.impl.StandardFileSystemManager;
import org.apache.commons.vfs2.provider.sftp.SftpFileSystemConfigBuilder;

public class SendMyFiles {

 static Properties props;

 public static void main(String[] args) {

  SendMyFiles sendMyFiles = new SendMyFiles();
  if (args.length < 1)
  {
   System.err.println("Usage: java " + sendMyFiles.getClass().getName()+
     " Properties_file File_To_FTP ");
   System.exit(1);
  }

  String propertiesFile = args[0].trim();
  String fileToFTP = args[1].trim();
  sendMyFiles.startFTP(propertiesFile, fileToFTP);

 }

 public boolean startFTP(String propertiesFilename, String fileToFTP){

  props = new Properties();
  StandardFileSystemManager manager = new StandardFileSystemManager();

  try {

   props.load(new FileInputStream("properties/" + propertiesFilename));
   String serverAddress = props.getProperty("serverAddress").trim();
   String userId = props.getProperty("userId").trim();
   String password = props.getProperty("password").trim();
   String remoteDirectory = props.getProperty("remoteDirectory").trim();
   String localDirectory = props.getProperty("localDirectory").trim();

   //check if the file exists
   String filepath = localDirectory +  fileToFTP;
   File file = new File(filepath);
   if (!file.exists())
    throw new RuntimeException("Error. Local file not found");

   //Initializes the file manager
   manager.init();

   //Setup our SFTP configuration
   FileSystemOptions opts = new FileSystemOptions();
   SftpFileSystemConfigBuilder.getInstance().setStrictHostKeyChecking(
     opts, "no");
   SftpFileSystemConfigBuilder.getInstance().setUserDirIsRoot(opts, true);
   SftpFileSystemConfigBuilder.getInstance().setTimeout(opts, 10000);

   //Create the SFTP URI using the host name, userid, password,  remote path and file name
   String sftpUri = "sftp://" + userId + ":" + password +  "@" + serverAddress + "/" + 
     remoteDirectory + fileToFTP;

   // Create local file object
   FileObject localFile = manager.resolveFile(file.getAbsolutePath());

   // Create remote file object
   FileObject remoteFile = manager.resolveFile(sftpUri, opts);

   // Copy local file to sftp server
   remoteFile.copyFrom(localFile, Selectors.SELECT_SELF);
   System.out.println("File upload successful");

  }
  catch (Exception ex) {
   ex.printStackTrace();
   return false;
  }
  finally {
   manager.close();
  }

  return true;
 }


}

Download file from remote server using SFTP

import java.io.File;
import java.io.FileInputStream;
import java.util.Properties;

import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.Selectors;
import org.apache.commons.vfs2.impl.StandardFileSystemManager;
import org.apache.commons.vfs2.provider.sftp.SftpFileSystemConfigBuilder;

public class GetMyFiles {

 static Properties props;

 public static void main(String[] args) {

  GetMyFiles getMyFiles = new GetMyFiles();
  if (args.length < 1)
  {
   System.err.println("Usage: java " + getMyFiles.getClass().getName()+
   " Properties_filename File_To_Download ");
   System.exit(1);
  }

  String propertiesFilename = args[0].trim();
  String fileToDownload = args[1].trim();
  getMyFiles.startFTP(propertiesFilename, fileToDownload);

 }

 public boolean startFTP(String propertiesFilename, String fileToDownload){

  props = new Properties();
  StandardFileSystemManager manager = new StandardFileSystemManager();

  try {

   props.load(new FileInputStream("properties/" + propertiesFilename));
   String serverAddress = props.getProperty("serverAddress").trim();
   String userId = props.getProperty("userId").trim();
   String password = props.getProperty("password").trim();
   String remoteDirectory = props.getProperty("remoteDirectory").trim();
   String localDirectory = props.getProperty("localDirectory").trim();


   //Initializes the file manager
   manager.init();

   //Setup our SFTP configuration
   FileSystemOptions opts = new FileSystemOptions();
   SftpFileSystemConfigBuilder.getInstance().setStrictHostKeyChecking(
     opts, "no");
   SftpFileSystemConfigBuilder.getInstance().setUserDirIsRoot(opts, true);
   SftpFileSystemConfigBuilder.getInstance().setTimeout(opts, 10000);

   //Create the SFTP URI using the host name, userid, password,  remote path and file name
   String sftpUri = "sftp://" + userId + ":" + password +  "@" + serverAddress + "/" + 
     remoteDirectory + fileToDownload;

   // Create local file object
   String filepath = localDirectory +  fileToDownload;
   File file = new File(filepath);
   FileObject localFile = manager.resolveFile(file.getAbsolutePath());

   // Create remote file object
   FileObject remoteFile = manager.resolveFile(sftpUri, opts);

   // Copy local file to sftp server
   localFile.copyFrom(remoteFile, Selectors.SELECT_SELF);
   System.out.println("File download successful");

  }
  catch (Exception ex) {
   ex.printStackTrace();
   return false;
  }
  finally {
   manager.close();
  }

  return true;
 }

}

Delete a file on remote server using SFTP

import java.io.FileInputStream;
import java.util.Properties;

import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.impl.StandardFileSystemManager;
import org.apache.commons.vfs2.provider.sftp.SftpFileSystemConfigBuilder;

public class DeleteRemoteFile {

 static Properties props;

 public static void main(String[] args) {

  DeleteRemoteFile getMyFiles = new DeleteRemoteFile();
  if (args.length < 1)
  {
   System.err.println("Usage: java " + getMyFiles.getClass().getName()+
   " Properties_filename File_To_Delete ");
   System.exit(1);
  }

  String propertiesFilename = args[0].trim();
  String fileToDownload = args[1].trim();
  getMyFiles.startFTP(propertiesFilename, fileToDownload);

 }

 public boolean startFTP(String propertiesFilename, String fileToDownload){

  props = new Properties();
  StandardFileSystemManager manager = new StandardFileSystemManager();

  try {

   props.load(new FileInputStream("properties/" + propertiesFilename));
   String serverAddress = props.getProperty("serverAddress").trim();
   String userId = props.getProperty("userId").trim();
   String password = props.getProperty("password").trim();
   String remoteDirectory = props.getProperty("remoteDirectory").trim();


   //Initializes the file manager
   manager.init();

   //Setup our SFTP configuration
   FileSystemOptions opts = new FileSystemOptions();
   SftpFileSystemConfigBuilder.getInstance().setStrictHostKeyChecking(
     opts, "no");
   SftpFileSystemConfigBuilder.getInstance().setUserDirIsRoot(opts, true);
   SftpFileSystemConfigBuilder.getInstance().setTimeout(opts, 10000);

   //Create the SFTP URI using the host name, userid, password,  remote path and file name
   String sftpUri = "sftp://" + userId + ":" + password +  "@" + serverAddress + "/" + 
     remoteDirectory + fileToDownload;

   //Create remote file object
   FileObject remoteFile = manager.resolveFile(sftpUri, opts);

   //Check if the file exists
   if(remoteFile.exists()){
    remoteFile.delete();
    System.out.println("File delete successful");
   }

  }
  catch (Exception ex) {
   ex.printStackTrace();
   return false;
  }
  finally {
   manager.close();
  }

  return true;
 }

}