I'm developing an application using Spring MVC. In a business process, an image file is generated which needs to retrieved to web server from the application server. I'm using the commons-net api to do it the simple way.
public class FtpUtility{
private FTPClient ftpClient = new FTPClient();
public boolean retriveFileFromApp(String srcFile, String destFile){
boolean flag = false;
try{
connectToFtp()
File dest = new File(destFile);
if(!dest.exists())
dest.mkdirs();
if(dest.exists())
dest.delete();
FileOutputStream destStream = new FileOutputStream(dest);
ftpClient.retrieveFile(srcFile, destStream);
}
catch(Exception e){
//exception handling
}
finally{
disconnect();
}
return flag;
}
private boolean connectToFtp(){
boolean flag = false;
try{
ftpClient.connect(appserverip); // connect to ftp
flag = ftpClient.login(ftpUserId, ftpPassword);
}
catch(Exception e){
//exception handling
}
return flag;
}
private void disconnect(){
try{
ftpClient.logout();
ftpClient.disconnect();
}
catch(Exception e){
//some exception handling
}
}
}
Now while multiple users are using this application, they are simultaneously connecting using an instance of this class and then disconnecting. Even a single user is connecting and disconnecting for each file transfer.
How can I effectively do this like connecting once, then doing the all transfer and then disconnecting, not opening and closing the connection for each transfer.
Will use of static help? If yes how?
This isn't going to work. Either the FTP client is static and you connect it once and use it serially via synchronization, or it is per-session and each session creates and connects and uses its own concurrently. Your present mixture of both can't work.
Related
I'm facing an issue when trying to store a file in an FTP server. When trying to upload a file to the FTP server, the file is created but its contents are not copied.
Context
We use the following configuration to access the FTP server using lftp. I cannot change this configuration, and don't know why do we use FTPS with verify-certificates disabled.
# FTPS_OPTIONS:
set ssl:verify-certificate/testhostname no;
set ftp:ssl-protect-data yes;
set ftp:passive-mode on;
I need to store certain files from a Java application. I'm using apache-commons library. The implemented code looks like this:
#Autowired
public FtpService() {
ftpsClient = new FTPSClient();
ftpsClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out), true));
}
public void uploadFile(String ftpHost, File tempFile, String destination, String filename)
throws UploadException {
ftpsClient.connect(ftpHost, 990);
ftpsClient.execPBSZ(0);
ftpsClient.execPROT("P");
ftpsClient.enterLocalPassiveMode();
ftpsClient.setKeepAlive(true);
ftpsClient.setControlKeepAliveTimeout(3000);
if(ftpsClient.login("user", "password")) {
try (InputStream fileStream = new FileInputStream(tempFile)) {
if (!ftpsClient.changeWorkingDirectory(destination)) {
throwUploadException("Destination directory not available in FTP server");
}
boolean saved = ftpsClient.storeFile(filename, fileStream);
// Following code is not executed since the exception is thrown in the previous line
if (!saved) {
throwUploadException("Unable to save file in FTP server");
}
log.info("Saved FTP file: {}/{}", destination, filename);
}
catch (UploadException | IOException e)
{
throwUploadException(e.getMessage());
}
finally
{
ftpsClient.disconnect();
if (!tempFile.delete()) {
log.warn("Unable to delete '{}' file", tempFile.getAbsolutePath());
}
}
}
}
Problem
I started with a FTPClient (non FTPSClient) but this way I wasn't able to login.
Currently (FTPSClient), I can:
change the working directory
create directories in the FTP server
I cannot:
storeFile: this method throws the following exception, and creates the file in the FTP server, but this is empty
org.apache.commons.net.io.CopyStreamException: IOException caught while copying.
Cause: javax.net.ssl.SSLProtocolException: Software caused connection abort: socket write error
listFiles()/listDirectories(): when executing this command, the obtained list is always empty. The logged user has all the required permissions in the whole FTP server
Following is the FTP's log (note that I have translated the commands to English between parenthesis), corresponding to the code shown before, that raises the exception mentioned before:
er: testhostname:990
USER *******
331 Usuario testuser OK. Clave requerida ( = User testuser OK. Password required)
PASS *******
230 OK. El directorio restringido actual es / ( = OK. The current restricted directory is /)
CWD /test/upload
250 OK. El directorio actual es /test/upload ( = Ok. The current directory is /test/upload)
PASV
227 Entering Passive Mode (<numbers...>)
[Replacing PASV mode reply address <ip_address> with testhostname]
STOR dummyfile.txt
150 Conexi├│n de datos aceptada ( = Data connection accepted)
If there is anything else I can include to improve the description, please let me know. Thanks for your help!
I had a similar problem from python connecting to an FTPS server. The error was that the server required the data channel session to be the same as the control channel session(reuse the session). The solution was to override one of the methods to do that.
You can test extending FTPClient.java and overriding the next method:
#Override
protected void _prepareDataSocket_(final Socket socket) {
if(preferences.getBoolean("ftp.tls.session.requirereuse")) {
if(socket instanceof SSLSocket) {
// Control socket is SSL
final SSLSession session = ((SSLSocket) _socket_).getSession();
if(session.isValid()) {
final SSLSessionContext context = session.getSessionContext();
context.setSessionCacheSize(preferences.getInteger("ftp.ssl.session.cache.size"));
try {
final Field sessionHostPortCache = context.getClass().getDeclaredField("sessionHostPortCache");
sessionHostPortCache.setAccessible(true);
final Object cache = sessionHostPortCache.get(context);
final Method putMethod = cache.getClass().getDeclaredMethod("put", Object.class, Object.class);
putMethod.setAccessible(true);
Method getHostMethod;
try {
getHostMethod = socket.getClass().getMethod("getPeerHost");
}
catch(NoSuchMethodException e) {
// Running in IKVM
getHostMethod = socket.getClass().getDeclaredMethod("getHost");
}
getHostMethod.setAccessible(true);
Object peerHost = getHostMethod.invoke(socket);
putMethod.invoke(cache, String.format("%s:%s", peerHost, socket.getPort()).toLowerCase(Locale.ROOT), session);
}
catch(NoSuchFieldException e) {
// Not running in expected JRE
log.warn("No field sessionHostPortCache in SSLSessionContext", e);
}
catch(Exception e) {
// Not running in expected JRE
log.warn(e.getMessage());
}
}
else {
log.warn(String.format("SSL session %s for socket %s is not rejoinable", session, socket));
}
}
}
}
I found this Java solution here: https://stackoverflow.com/a/32404418/19599290
I am using socket.io-java-client to communicate with nodejs server.
In my app, there are 5 pages and I want to access the io client on all pages.
I have written a connection code in SocketConnection.java file.
public class SocketConnection {
private Socket mSocket;
{
try {
mSocket = IO.socket(SyncStateContract.Constants.CHAT_SERVER_URL);
mSocket.connect();
} catch (URISyntaxException e) {
throw new RuntimeException(e);
}
}
public Socket getSocket() {
return mSocket;
}
}
But I am importing to file it is creating a new connection every time and because of which more than one connection takes place.
Anyone has any Idea how I set up the IO java client for more than one page.
How to check if server is online or offline, and if is offline start connecting until server is on. I have tried with this:
connectBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new Thread(rConnection).start();
}
});
public Runnable rConnection = new Runnable() {
#Override
public void run() {
boolean status = connect();
while (!status)
{
System.out.println("Connection Status: " + status);
status = Connect();
}
}
};
public boolean Connect() {
boolean status = false;
try {
s = new Socket(SERVER_ADDRESS, TCP_SERVER_PORT);
System.out.println("Socket: " + s.toString());
if (s.toString() != "")
{
status = true;
}
} catch (UnknownHostException e) {
e.printStackTrace();
status = false;
s=null;
} catch (IOException e) {
e.printStackTrace();
status = false;
s=null;
} catch (NullPointerException e)
{
e.printStackTrace();
status = false;
s=null;
}
return status;
}
If server is running before staring app it connects successfully but if server is off or disconnects after some time I don't get any error message and it won't start reconnecting again. How to solve this?
Basically you may split this:
s = new Socket(SERVER_ADDRESS, TCP_SERVER_PORT);
into
s = new Socket();
s.connect(remoteAddr,timeout)
And then control if connect returns on timeout or on successfull connection.
Look at this thread for a solution and keywords: How can I monitor the network connection status in Android? . Also, consider retrying requests on a new connection if the underlying connection is lost (or times out).
How to check if server is online or offline, and if is offline start connecting until server is on
Try to connect to it when you need to connect to it, and handle the failures that result. At present you seem to be trying to maintain an eternal connection, which is never going to work. The best way to detect whether a resource is available is to try to use it at the time that you need to use it. Anything is subject to numerous sources of error such as timing window problems, testing the wrong thing, testing the right thing at the wrong time, and at best to overuse of scarce resources. Rethink your requirement.
Part of a Java program I'm creating needs to talk to a service on a remote machine. That remote machine is running a service (written in Delphi I believe) on a Windows platform.
I need to connect to that machine, send command strings and receive (String) responses.
If I connect using Linux CLI telnet session I get responses as expected:
[dafoot#bigfoot ~]$ telnet [host IP] [host port]
Trying [host IP]...
Connected to [host IP].
Escape character is '^]'.
Welcome to MidWare server
ping
200 OK
ProcessDownload 4
200 OK
In the above the lines 'ping' and 'ProcessDownload 4' are me typing in the terminal, other lines are responses from remote system.
I created a Main in my Java class that will do the work to call the appropriate methods to try and test this (I've left out irrelevant stuff):
public class DownloadService {
Socket _socket = null; // socket representing connecton to remote machine
PrintWriter _send = null; // write to this to send data to remote server
BufferedReader _receive = null; // response from remote server will end up here
public DownloadServiceImpl() {
this.init();
}
public void init() {
int remoteSocketNumber = 1234;
try {
_socket = new Socket("1.2.3.4", remoteSocketNumber);
} catch (IOException e) {
e.printStackTrace();
}
if(_socket !=null) {
try {
_send = new PrintWriter(_socket.getOutputStream(), true);
_receive = new BufferedReader(new InputStreamReader(_socket.getInputStream()));
} catch (IOException e) {
e.printStackTrace();
}
}
}
public boolean reprocessDownload(int downloadId) {
String response = null;
this.sendCommandToProcessingEngine("Logon", null);
this.sendCommandToProcessingEngine("ping", null);
this.sendCommandToProcessingEngine("ProcessDownload", Integer.toString(downloadId));
try {
_socket.close();
} catch (IOException e) {
e.printStackTrace();
}
return false;
}
private String sendCommandToProcessingEngine(String command, String param) {
String response = null;
if(!_socket.isConnected()) {
this.init();
}
System.out.println("send '"+command+"("+param+")'");
_send.write(command+" "+param);
try {
response = _receive.readLine();
System.out.println(command+"("+param+"):"+response);
return response;
} catch (IOException e2) {
e2.printStackTrace();
}
return response;
}
public static void main(String[] args) {
DownloadServiceImpl service = new DownloadServiceImpl();
service.reprocessDownload(0);
}
}
As you will see in the code, there are a couple of sys.outs to indicate when the program is attempting to send/receive data.
The output generated:
send 'Logon(null)'
Logon(null):Welcome to MidWare server
send 'ping(null)'
So Java is connecting to the server ok to get the "Welcome to Midware" message back, but when I try to send a command ('ping') I don't get a response.
So the questions:
- does the Java look about right?
- could problem be related to character encoding (Java -> windows)?
You need to flush the output stream:
_send.write(command+" "+param+"\n"); // Don't forget new line here!
_send.flush();
or, since you create a auto-flushing PrintWriter:
_send.println(command+" "+param);
The latter has the disadvantage that the line end can be \n or \r\n, depending on the system on which your Java VM runs. So I prefer the first solution.
Please figure this out. The code runs properly without any exception.
try
{
FTPClient ftp = new FTPClient();
ftp.connect(server);
if(!ftp.login(username, password))
{
ftp.logout();
return false;
}
int reply = ftp.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply))
{
ftp.disconnect();
return false;
}
InputStream in = new FileInputStream(localfile);
ftp.setFileType(ftp.BINARY_FILE_TYPE, ftp.BINARY_FILE_TYPE);
ftp.setFileTransferMode(ftp.BINARY_FILE_TYPE);
Store = ftp.storeFile(destinationfile, in);
in.close();
ftp.logout();
ftp.disconnect();
}
catch (Exception ex)
{
ex.printStackTrace();
return false;
}
return Store;
Butm the return statement always returns false and the file is not uploaded on the server. Someone please help on this.
For your information, I am in an office network. ---> do we need to add any proxies?
File file = new File("C:\\Users\\sg0214273\\Desktop\\seagate\\seagate.txt");
FileInputStream input = new FileInputStream(file);
client.setFileType(FTP.BINARY_FILE_TYPE);
if (!client.storeFile(file.getName(), input)) {
System.out.println("upload failed!");
}
reply = client.getReplyCode();
if(!FTPReply.isPositiveCompletion(reply)) {
System.out.println("upload failed!");
}
Login success...
230 User ******** logged in.
upload failed!-----> is form boolean return value of storefile
upload failed!---------> is from replycode...
Logout from FTP server...
Please help out.
The exact failure message can be found by calling FtpClient#getReplyCode(). From that page (my emphasis):
Immediately after connecting is the only real time you need to check
the reply code (because connect is of type void). The convention for
all the FTP command methods in FTPClient is such that they either
return a boolean value or some other value. The boolean methods return
true on a successful completion reply from the FTP server and false on
a reply resulting in an error condition or failure. The methods
returning a value other than boolean return a value containing the
higher level data produced by the FTP command, or null if a reply
resulted in an error condition or failure. If you want to access the
exact FTP reply code causing a success or failure, you must call
getReplyCode after a success or failure.
To see what a return code means, you can see Wikipedia: List of FTP server return codes.
Topic is quite old but maybe I will help to any other. I compared what FileZilla sends to FTP server and my program did. I needed to use ftp.enterLocalPassiveMode() to make it work, ftp.pasv() no good :)
And for debugging is better to use getReplyString() than only getReplyCode().
Modify you code to switch to passive mode before you transfer the file with storeFile() as follows:
...
ftp.setFileTransferMode(ftp.BINARY_FILE_TYPE);
ftp.enterLocalPassiveMode();//Switch to passive mode
Store = ftp.storeFile(destinationfile, in);
in.close();
...
Hope that helps.
please add the apache library for this code
this are the impoted class
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
rest import class is from java.io or java.net
public boolean upload(String server,String username,String password,File localfile ){
boolean Store=false;
try{
FTPClient ftp = new FTPClient();
// ftp.connect(server);
/* you can use either code which is written above above or below code as ftp port 20 is used for the data transfer and port 21 is used for command and controlls */
ftp.connect(InetAddress.getByName(server),21);
//here 'server' is your domain name of ftp server or url
if(!ftp.login(username, password))
{
ftp.logout();
return false;
}
ftp.sendNoOp();//used so server timeout exception will not rise
int reply = ftp.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply))
{
ftp.disconnect();
return false;
}
ftp.enterLocalPassiveMode(); /* just include this line here and your code will work fine */
InputStream in = new FileInputStream(localfile);
// ftp.setFileType(ftp.BINARY_FILE_TYPE, ftp.BINARY_FILE_TYPE);
ftp.setFileType(FTP.BINARY_FILE_TYPE);
// ftp.setFileTransferMode(ftp.BINARY_FILE_TYPE);
Store = ftp.storeFile(destinationfile, in);
in.close();
//ftp.disconnect();
//here logout will close the connection for you
ftp.logout();
}
catch (Exception ex)
{
ex.printStackTrace();
return false;
}
return Store;
}
Try to use ftp.enterLocalPassiveMode(); before ftp.storeFile(destinationfile, in);