Retrieving data from an SFTP server using JSch

问题:

I am using JSch for retrieving a file from a remote machine by SFTP. Here is the code

public class TestSFTPinJava {   public static void main(String args[]) {         JSch jsch = new JSch();         Session session = null;         try {             session = jsch.getSession("username", "sftp.abc.com", 22);             session.setConfig("StrictHostKeyChecking", "no");             session.setPassword("password");             session.connect();              Channel channel = session.openChannel("sftp");             channel.connect();             ChannelSftp sftpChannel = (ChannelSftp) channel;             System.out.println("Directory:" + sftpChannel.pwd());             sftpChannel.cd("remoteDirectory/");             System.out.println("Directory after cd:" + sftpChannel.pwd());             sftpChannel.get("remote-data.txt");              sftpChannel.put("C:\\Users\\mona\\Documents\\local-copy.txt");             sftpChannel.exit();             session.disconnect();         } catch (JSchException e) {             e.printStackTrace();           } catch (SftpException e) {             e.printStackTrace();         }     } } 

Now, I have two questions:

• sftpChannel.get("remote-data.txt"); throws an exception:

  no such file
  at com.jcraft.jsch.ChannelSftp.throwStatusError(ChannelSftp.java:2297)
  at com.jcraft.jsch.ChannelSftp._stat(ChannelSftp.java:1750)
  at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:1020)
  at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:995)
  at TestSFTPinJava.main(TestSFTPinJava.java:29)

• I am not sure how to specify the location in my local system where the file will be saved. sftpChannel.put("C:\\Users\\mona\\Documents\\localCopy.txt"); does not look right to me.

Please help with suggestions, Thanks!

回答1:

Concerning your point 1, I suspect that the default directory after connecting is not what you expect. Try using an absolute remote path. Does sftpChannel.pwd() return the directory the file remote-data.txt is in on the remote machine ?

Concerning your point 2, looking at http://grepcode.com/file/repo1.maven.org/maven2/com.jcraft/jsch/0.1.42/com/jcraft/jsch/ChannelSftp.java#290 one sees that there is the following method in ChannelSftp:

 public void put(String src, String dst) 

which indeed has a source and destination file name argument.

I guess you had already a look the Jsch sftp example at http://www.jcraft.com/jsch/examples/Sftp.java ?

回答2:

Simple example of app. I get file from remote server (from /tmp/qtmp) and save it in local machine in the current path

package connector;  import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream;  import com.jcraft.jsch.ChannelSftp; import com.jcraft.jsch.JSch; import com.jcraft.jsch.JSchException; import com.jcraft.jsch.Session; import com.jcraft.jsch.SftpException;  public class Fetcher {      public void fetchFile(String username, String host, String passwd) throws JSchException, SftpException, IOException {         JSch conn = new JSch();         Session session = null;         session = conn.getSession(username, host, 22);         session.setPassword(passwd);         session.setConfig("StrictHostKeyChecking", "no");         session.connect();          ChannelSftp channel = (ChannelSftp)session.openChannel("sftp");         channel.connect();          //change folder on the remote server         channel.cd("/tmp/qtmp");          InputStream in = channel.get("testScp");         // set local file         String lf = "OBJECT_FILE";         FileOutputStream tergetFile = new FileOutputStream(lf);          // read containts of remote file to local         int c;         while ( (c= in.read()) != -1 ) {             tergetFile.write(c);         }           in.close();         tergetFile.close();          channel.disconnect();         session.disconnect();         }  } 

回答3:

i had a similar issue, i was trying to get some files from a server where everything was fine, but i was getting always this error:

sftpChannel.get("fil1.txt","file1.txt")  error message:   2: No such file at com.jcraft.jsch.ChannelSftp.throwStatusError(ChannelSftp.java:2846) at com.jcraft.jsch.ChannelSftp._stat(ChannelSftp.java:2198) at com.jcraft.jsch.ChannelSftp._stat(ChannelSftp.java:2215) at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:913) at com.jcraft.jsch.ChannelSftp.get(ChannelSftp.java:873) ... 

I was listing properly all the elements of the directory by using

java.util.Vector v1 = sftpChannel.ls(dir); 

I think that was that confused me, that i was able to read the content of the directory by using the ls command, when you want to get / put files make sure you move first by using "cd".

The solution was to use the next command to move to the directory that contains my files using a simple cd command:

sftpChannel.cd(dir); 

Hope this helps, i took my sometime to figure it out. jojo.

Lessons learned:

1.- ls can read any directory no matter if you are not inside of it. 2.- To get and put files always make sure you are in the directory that contains the files by using cd.

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