Finding file size and last modified of SFTP oldest file using Java

I'm using JSch to get files from an SFTP server, but I'm trying to figure out a way to only get the oldest file, and to make sure that it is not currently being written to. The way I imagine myself doing this is first finding which file in the specified remote folder is oldest. I would then check the file size, wait x seconds (probably about 10, just to be safe) and then check it again. If the file size has not changed, I download the file and process it. However, I have no idea how to do this! If anybody knows how to do this, or knows of something else that supports SFTP that ha开发者_C百科s this built-in (I know Apache Commons does, but only does FTPS), it would be greatly appreciated.

Thanks in advance.

Turns out that this is entirely possible in JSch, the hardest part is simply finding the documentation. Code I used is below, hopefully somebody else will find it helpful! (I'm sure there are optimizations to be made, I know, I know. There are also variables that are defined elsewhere, but hopefully anybody that needs this will be able to figure them out!)

public static String oldestFile() {
    Vector list = null;
    int currentOldestTime;
    int nextTime = 2140000000; //Made very big for future-proofing
    ChannelSftp.LsEntry lsEntry = null;
    SftpATTRS attrs = null;
    String nextName = null;
    try {
        list = Main.chanSftp.ls("*.xml");
        if (list.isEmpty()) {
            fileFound = false;
        }
        else {
            lsEntry = (ChannelSftp.LsEntry) list.firstElement();
            oldestFile = lsEntry.getFilename();
            attrs = lsEntry.getAttrs();
            currentOldestTime = attrs.getMTime();
            for (Object sftpFile : list) {
                lsEntry = (ChannelSftp.LsEntry) sftpFile;
                nextName = lsEntry.getFilename();
                attrs = lsEntry.getAttrs();
                nextTime = attrs.getMTime();
                if (nextTime < currentOldestTime) {
                    oldestFile = nextName;
                    currentOldestTime = nextTime;
                }
            }
            attrs = chanSftp.lstat(Main.oldestFile);
            long size1 = attrs.getSize();
            System.out.println("-Ensuring file is not being written to (waiting 1 minute)");
            Thread.sleep(60000); //Wait a minute to make sure the file size isn't changing
            attrs = chanSftp.lstat(Main.oldestFile);
            long size2 = attrs.getSize();
            if (size1 == size2) {
                System.out.println("-It isn't.");
                fileFound = true;
            }
            else {
                System.out.println("-It is.");
                fileFound = false;
            }
        }
    } catch (Exception ex) {ex.printStackTrace();}
    return Main.oldestFile;
}

You can easily do this using edtFTPj/PRO, which supports SFTP.

Simply get a directory listing, and sort the listing by date. If the oldest date isn't in the last few minutes, you can download.

I don't have a direct answer to your question, but it sounds like you want to do something similar to reliable file transfer. This is part of a larger project in Grid computing that is now apparently organized here. I don't know if it includes security features or if you can add them on, but it is an open source project.

calculate the folder size in remote server just call the ftpFolderSize(ftpFolderSize,client) directory path, and pass the object FTPClient as a parameter. It will return the size of folder.

Works only for FTP.

import org.apache.commons.net.ftp.FTPClient;

import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.io.FileUtils;

long dirSize = 0L; //global variable

private long ftpFolderSize(String directoryPath,FTPClient client){

    try{
        client.changeWorkingDirectory(directoryPath); 
        FTPFile[] ftpFiles = client.listFiles();
        if(client.changeWorkingDirectory(directoryPath))
        {
            for (FTPFile ftpFile : ftpFiles) {
                if(ftpFile.isFile()){
                    dirSize = dirSize+ftpFile.getSize();// file size is calculated
                }
                else if(ftpFile.isDirectory())
                {
                    dirSize = dirSize + 4096;//folder minimum size is 4kb
                    ftpFolderSize(directoryPath+"/"+ftpFile.getName(),client);
                }

            }
        }
    }catch (Exception e) {
        e.printStackTrace();
    }
    return dirSize;
}