问题
I'm using Apache Commons FTP to upload a file. Before uploading I want to check if the file already exists on the server and make a backup from it to a backup directory on the same server.
Does anyone know how to copy a file from a FTP server to a backup directory on the same server?
public static void uploadWithCommonsFTP(File fileToBeUpload){
FTPClient f = new FTPClient();
FTPFile backupDirectory;
try {
f.connect(server.getServer());
f.login(server.getUsername(), server.getPassword());
FTPFile[] directories = f.listDirectories();
FTPFile[] files = f.listFiles();
for(FTPFile file:directories){
if (!file.getName().equalsIgnoreCase("backup")) {
backupDirectory=file;
} else {
f.makeDirectory("backup");
}
}
for(FTPFile file: files){
if(file.getName().equals(fileToBeUpload.getName())){
//copy file to backupDirectory
}
}
} catch (IOException e) {
e.printStackTrace();
}
}
Edited code: still there is a problem, when i backup zip file, the backup-ed file is corrupted.
Does any body know the reason for it?
public static void backupUploadWithCommonsFTP(File fileToBeUpload) {
FTPClient f = new FTPClient();
boolean backupDirectoryExist = false;
boolean fileToBeUploadExist = false;
FTPFile backupDirectory = null;
try {
f.connect(server.getServer());
f.login(server.getUsername(), server.getPassword());
FTPFile[] directories = f.listDirectories();
// Check for existence of backup directory
for (FTPFile file : directories) {
String filename = file.getName();
if (file.isDirectory() && filename.equalsIgnoreCase("backup")) {
backupDirectory = file;
backupDirectoryExist = true;
break;
}
}
if (!backupDirectoryExist) {
f.makeDirectory("backup");
}
// Check if file already exist on the server
f.changeWorkingDirectory("files");
FTPFile[] files = f.listFiles();
f.changeWorkingDirectory("backup");
String filePathToBeBackup="/home/user/backup/";
String prefix;
String suffix;
String fileNameToBeBackup;
FTPFile fileReadyForBackup = null;
f.setFileType(FTP.BINARY_FILE_TYPE);
f.setFileTransferMode(FTP.BINARY_FILE_TYPE);
for (FTPFile file : files) {
if (file.isFile() && file.getName().equals(fileToBeUpload.getName())) {
prefix = FilenameUtils.getBaseName(file.getName());
suffix = ".".concat(FilenameUtils.getExtension(file.getName()));
fileNameToBeBackup = prefix.concat(Calendar.getInstance().getTime().toString().concat(suffix));
filePathToBeBackup = filePathToBeBackup.concat(fileNameToBeBackup);
fileReadyForBackup = file;
fileToBeUploadExist = true;
break;
}
}
// If file already exist on the server create a backup from it otherwise just upload the file.
if(fileToBeUploadExist){
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
f.retrieveFile(fileReadyForBackup.getName(), outputStream);
InputStream is = new ByteArrayInputStream(outputStream.toByteArray());
if(f.storeUniqueFile(filePathToBeBackup, is)){
JOptionPane.showMessageDialog(null, "Backup succeeded.");
f.changeWorkingDirectory("files");
boolean reply = f.storeFile(fileToBeUpload.getName(), new FileInputStream(fileToBeUpload));
if(reply){
JOptionPane.showMessageDialog(null,"Upload succeeded.");
}else{
JOptionPane.showMessageDialog(null,"Upload failed after backup.");
}
}else{
JOptionPane.showMessageDialog(null,"Backup failed.");
}
}else{
f.changeWorkingDirectory("files");
f.setFileType(FTP.BINARY_FILE_TYPE);
f.enterLocalPassiveMode();
InputStream inputStream = new FileInputStream(fileToBeUpload);
ByteArrayInputStream in = new ByteArrayInputStream(FileUtils.readFileToByteArray(fileToBeUpload));
boolean reply = f.storeFile(fileToBeUpload.getName(), in);
System.out.println("Reply code for storing file to server: " + reply);
if(!f.completePendingCommand()) {
f.logout();
f.disconnect();
System.err.println("File transfer failed.");
System.exit(1);
}
if(reply){
JOptionPane.showMessageDialog(null,"File uploaded successfully without making backup." +
"\nReason: There wasn't any previous version of this file.");
}else{
JOptionPane.showMessageDialog(null,"Upload failed.");
}
}
//Logout and disconnect from server
in.close();
f.logout();
f.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}
回答1:
If you are using apache commons net FTPClient, there is a direct method to move a file from one location to another location (if the user has proper permissions).
ftpClient.rename(from, to);
or, If you are familiar with ftp commands, you can use something like
ftpClient.sendCommand(FTPCommand.yourCommand, args);
if(FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
//command successful;
} else {
//check for reply code, and take appropriate action.
}
If you are using any other client, go through the documentation, There wont be much changes between client implementations.
UPDATE:
Above approach moves the file to to directory, i.e, the file won't be there in from directory anymore. Basically ftp protocol meant to be transfer the files from local <-> remote or remote <-> other remote but not to transfer with in the server.
The work around here, would be simpler, get the complete file to a local InputStream and write it back to the server as a new file in the back up directory.
to get the complete file,
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ftpClient.retrieveFile(fileName, outputStream);
InputStream is = new ByteArrayInputStream(outputStream.toByteArray());
now, store this stream to backup directory. First we need to change working directory to backup directory.
// assuming backup directory is with in current working directory
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);//binary files
ftpClient.changeWorkingDirectory("backup");
//this overwrites the existing file
ftpClient.storeFile(fileName, is);
//if you don't want to overwrite it use storeUniqueFile
Hope this helps you..
回答2:
Try this way,
I am using apache's library .
ftpClient.rename(from, to) will make it easier, i have mentioned in the code below where to add ftpClient.rename(from,to).
public void goforIt(){
FTPClient con = null;
try
{
con = new FTPClient();
con.connect("www.ujudgeit.net");
if (con.login("ujud3", "Stevejobs27!!!!"))
{
con.enterLocalPassiveMode(); // important!
con.setFileType(FTP.BINARY_FILE_TYPE);
String data = "/sdcard/prerakm4a.m4a";
ByteArrayInputStream(data.getBytes());
FileInputStream in = new FileInputStream(new File(data));
boolean result = con.storeFile("/Ads/prerakm4a.m4a", in);
in.close();
if (result)
{
Log.v("upload result", "succeeded");
//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$Add the backup Here$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//
// Now here you can store the file into a backup location
// Use ftpClient.rename(from, to) to place it in backup
//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$Add the backup Here$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$//
}
con.logout();
con.disconnect();
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
回答3:
There's no standard way to duplicate a remote file over FTP protocol. Some FTP servers support proprietary or non-standard extensions for this though.
So if your are lucky that your server is ProFTPD with mod_copy module, you can use FTP.sendCommand to issue these two commands:
f.sendCommand("CPFR sourcepath");
f.sendCommand("CPTO targetpath");
The second possibility is that your server allows you to execute arbitrary shell commands. This is even less common. If your server supports this you can use SITE EXEC command:
SITE EXEC cp -p sourcepath targetpath
Another workaround is to open a second connection to the FTP server and make the server upload the file to itself by piping a passive mode data connection to an active mode data connection. Implementation of this solution (in PHP though) is shown in FTP copy a file to another place in same FTP.
If neither of this works, all you can do is to download the file to a local temporary location and re-upload it back to the target location. This is that the answer by @RP- shows.
See also FTP copy a file to another place in same FTP.
回答4:
To backup at same Server (move), can you use:
String source="/home/user/some";
String goal ="/home/user/someOther";
FTPFile[] filesFTP = cliente.listFiles(source);
clientFTP.changeWorkingDirectory(goal); // IMPORTANT change to final directory
for (FTPFile f : archivosFTP)
{
if(f.isFile())
{
cliente.rename(source+"/"+f.getName(), f.getName());
}
}
来源：https://stackoverflow.com/questions/11202215/how-to-copy-a-file-on-the-ftp-server-to-a-directory-on-the-same-server-in-java