Downloading files from an SFTP server using JSch

Question

I am using jsch to download files from server, my code below.

public static void downloadFile(TpcCredentialsDTO dto) {
        logger.trace(\"Entering downlo         


        

Answer 1

Please find in the below code sample comprising the file upload and download functionalities. Please pull the relevant details from properties files where ever string marked in lt;sftp.user.namegt;. I am deleting the file once the file is downloaded you can have it as per your requirement.

The event and locale parameters what I have added as part of download functionality is to filter the file(s); you can pass parameters as par you need.

Have placed a check to set proxy which can be used on need basis.

package com.util;

import com.jcraft.jsch.Channel;
import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.ProxyHTTP;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.SftpException;
import java.io.File;
import java.io.FileInputStream;
import java.util.Date;
import java.util.Properties;
import java.util.Vector;

/**
 *
 * @author Dinesh.Lomte
 */
public class SftpUtil {

    /**
     * 
     * @param fileName
     * @throws Exception 
     */
    public static void upload(String fileName)
    throws Exception {

        String method = "upload(String fileName)";
        Session session = null;
        Channel channel = null;
        ChannelSftp channelSftp = null;
        try {
            // Creating and instantiating the jsch specific instance
            JSch jsch = new JSch();
            // Fetching and setting the parameters like: user name, host and port 
            // from the properties file
            session = jsch.getSession("<sftp.user.name>",
                    "<sftp.host>",
                    Integer.valueOf("<sftp.port>"));
            // Fetching and setting the password as configured in properties files
            session.setPassword("<sftp.user.password>");
            // Setting the configuration specific properties
            Properties config = new Properties();
            config.put("StrictHostKeyChecking", "no");
            session.setConfig(config);            
            // Validating if proxy is enabled to access the sftp
            isSftpProxyEnabled(session);
            // Execution start time
            long lStartTime = new Date().getTime();
            System.out.println("Connecting to the sftp...");
            // Connecting to the sftp 
            session.connect();
            System.out.println("Connected to the sftp.");            
            // Execution end time
            long lEndTime = new Date().getTime();
            System.out.println("---------------------------------------------");
            System.out.println("Connected to SFTP in : " + (lEndTime - lStartTime));
            // Setting the channel type as sftp
            channel = session.openChannel("sftp");
            // Establishing the connection
            channel.connect();
            channelSftp = (ChannelSftp) channel;
            // Setting the folder location of the external system as configured
            channelSftp.cd("<sftp.output.folder.url>");
            // Creating the file instance
            File file = new File(fileName);
            // Creating an fileInputStream instance
            FileInputStream fileInputStream = new FileInputStream(file);
            // Transfering the file from it source to destination location via sftp
            channelSftp.put(fileInputStream, file.getName());
            // Closing the fileInputStream instance
            fileInputStream.close();
            // De-allocating the fileInputStream instance memory by assigning null
            fileInputStream = null;
        } catch (Exception exception) {
            throw exception;
        } finally {
            // Validating if channel sftp is not null to exit
            if (channelSftp != null) {
                channelSftp.exit();
            }
            // Validating if channel is not null to disconnect
            if (channel != null) {
                channel.disconnect();
            }
            // Validating if session instance is not null to disconnect
            if (session != null) {
                session.disconnect();
            }
        }
    }

    /**
     * 
     * @param session 
     */
    private static void isSftpProxyEnabled(Session session) {
        // Fetching the sftp proxy flag set as part of the properties file
        boolean isSftpProxyEnabled = Boolean.valueOf("<sftp.proxy.enable>");
        // Validating if proxy is enabled to access the sftp
        if (isSftpProxyEnabled) {
            // Setting host and port of the proxy to access the SFTP
            session.setProxy(new ProxyHTTP("<sftp.proxy.host>", 
                    Integer.valueOf("<sftp.proxy.port>");
        }
        System.out.println("Proxy status: " + isSftpProxyEnabled);
    }

    /**
     * 
     * @param folder
     * @param event
     * @param locale
     */
    public static void download(String folder, String event, String locale) {

        String method = "download(String folder, String event, String locale)";
        Session session = null;
        Channel channel = null;
        ChannelSftp channelSftp = null;
        try {
            // Creating and instantiating the jsch specific instance
            JSch jsch = new JSch();
            // Fetching and setting the parameters like: user name, host and port 
            // from the properties file
            session = jsch.getSession("<sftp.user.name>",
                    "<sftp.host>",
                    Integer.valueOf("<sftp.port>"));
            // Fetching and setting the password as configured in properties files
            session.setPassword("<sftp.user.password>");
            // Setting the configuration specific properties
            Properties config = new Properties();
            config.put("StrictHostKeyChecking", "no");
            session.setConfig(config);            
            // Validating if proxy is enabled to access the sftp
            isSftpProxyEnabled(session);
            // Execution start time
            long lStartTime = new Date().getTime();
            System.out.println("Connecting to the sftp...");
            // Connecting to the sftp 
            session.connect();
            System.out.println("Connected to the sftp.");            
            // Execution end time
            long lEndTime = new Date().getTime();
            System.out.println("---------------------------------------------");
            System.out.println("Connected to SFTP in : " + (lEndTime - lStartTime));
            // Setting the channel type as sftp
            channel = session.openChannel(SFTP);
            // Establishing the connection
            channel.connect();
            channelSftp = (ChannelSftp) channel;
            try {
                // Setting the folder location of the external system as configured 
                // to download the file from
                channelSftp.cd("<sftp.input.folder.url>");
            } catch (SftpException sftpException) {
                System.out.println("Failed to change the directory in sftp.");                
            }
            // Listing all the .csv file(s) specific to the source system, event type (download) and locale code
            Vector<ChannelSftp.LsEntry> lsEntries = channelSftp.ls(
                    new StringBuilder("*").append("<sys.code>").append("*").append(event)
                    .append("*").append(locale).append("*").append(".csv").toString());
            // Validating if files exist to process the request further
            if (lsEntries.isEmpty()) {
                System.out.println("No file exist in the specified sftp folder location.");
            }
            // Iterating the list of entries to download the file(s) from the sftp 
            for (ChannelSftp.LsEntry entry : lsEntries) {
                try {
                    // Downloading the specified file from the sftp to the specified folder path
                    channelSftp.get(entry.getFilename(), new StringBuilder(folder)
                            .append(File.separator).append(entry.getFilename()).toString());
                } catch (SftpException sftpException) {
                    System.out.println("Failed to download the file the sftp folder location.");                    
                }                
            }
            // Iterating the list of entries to delete the file(s) from the sftp 
            for (ChannelSftp.LsEntry entry : lsEntries) {
                try {
                    // Deleting the specified file from the sftp
                    channelSftp.rm(entry.getFilename());
                } catch (SftpException sftpException) {
                    System.out.println("Failed to delete the file from the sftp folder location.");                    
                }                
            }
        } catch (Exception exception) {
            System.out.println("Failed to download the file(s) from SFTP.");            
        } finally {
            // Validating if channel sftp is not null to exit
            if (channelSftp != null) {
                channelSftp.exit();
            }
            // Validating if channel is not null to disconnect
            if (channel != null) {
                channel.disconnect();
            }
            // Validating if session instance is not null to disconnect
            if (session != null) {
                session.disconnect();
            }
        }
    }
}

Answer 2

Try using paths instead of stream:

String destPath = "filename.txt";        

if (!filesToDownload.isEmpty()) {
    for (String fileDownloadName : filesToDownload) {
        success = false;
        sftpChannel.get(fileDownloadName , destPath);  

If you wanna use file and streams check this example:
http://kodehelp.com/java-program-for-downloading-file-from-sftp-server/

Answer 3

I fixed in this way:

Vector<ChannelSftp.LsEntry> files = sftp.ls(remotePath);
String remotePath = properties.getFtpPath();
Vector<ChannelSftp.LsEntry> files = sftp.ls(remotePath);

for (ChannelSftp.LsEntry entry : files) {

    InputStream stream = sftp.get(remotePath + "/" + entry.getFilename());
    // Your business code here

}

Where remotePath is the remote SFTP folder name.