CODEWITHSUNDEEP
javaftpftp-client
User412387
User412387

Reputation: 89

New file is getting created during FTP download

I'm trying to download a file from server using FTP, the Java code works if the file is available in remote server but if the specific file is not available in the remote server a new file is getting created with same file name in local. How can I avoid this?

and I'm trying to check the properties such as last modified time, file created time etc.., of the specific file before download, I used MLST but getting type casting issues..!!

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

public class FTPDownloadFileDemo {

public static void main(String[] args) {
    String server = "www.myserver.com";
    int port = 21;
    String user = "user";
    String pass = "pass";

    FTPClient ftpClient = new FTPClient();
    try {

        ftpClient.connect(server, port);
        ftpClient.login(user, pass);
        ftpClient.enterLocalPassiveMode();
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

        // APPROACH #1: using retrieveFile(String, OutputStream)
        String remoteFile1 = "/test/video.mp4";
        File downloadFile1 = new File("D:/Downloads/video.mp4");
        OutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(downloadFile1));
        boolean success = ftpClient.retrieveFile(remoteFile1, outputStream1);
        outputStream1.close();

        if (success) {
            System.out.println("File #1 has been downloaded successfully.");
        }

        outputStream2.close();
        inputStream.close();

    } catch (IOException ex) {
        System.out.println("Error: " + ex.getMessage());
        ex.printStackTrace();
    } finally {
        try {
            if (ftpClient.isConnected()) {
                ftpClient.logout();
                ftpClient.disconnect();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
}

}

Upvotes: 0

Views: 919

Answers (2)

AJWGeek
AJWGeek

Reputation: 141

The retrieveFile() method always writes a local file, whether or not the remote file exists. Instead, you can use retrieveFileStream() and check the reply code.

A handy list of FTP reply codes is available from Wikipedia. If 550 is received, it means the file does not exist.

Finally, you need to use completePendingCommand() to complete the transaction and a FileOutputStream to write the file. 

InputStream inputStream = ftpClient.retrieveFileStream(remoteFile1);
int returnCode = ftpClient.getReplyCode();
if (inputStream == null || returnCode == 550) {
    System.out.println("Remote file does not exist");
} else {
    ftpClient.completePendingCommand();
    byte[] buffer = new byte[inputStream.available()];
    inputStream.read(buffer);
    OutputStream outputStream = new FileOutputStream(downloadFile1);
    outputStream.write(buffer);
    outputStream.close();
}

Upvotes: 1

Christian
Christian

Reputation: 22343

Your problem is that your Outputstream automatically creates the File, even if the stream is empty.

I would recommend you check first if the file exists on the server and based on that you don't even create the outputStream:

boolean checkFileExists(String filePath) throws IOException {
    InputStream inputStream = ftpClient.retrieveFileStream(remoteFile1);
    returnCode = ftpClient.getReplyCode();
    return inputStream == null || returnCode == 550;
}

Upvotes: 1

Related Questions