Java - Getting corrupted JPG while uploading using FTP connection?

Question

The following code is being used to upload three JPG-Image files using FTP in JAVA. The files are uploaded and confirmed with a "successful"-message, but the files are corrupted. The small tiny thumbnails-files are partly readable (top quarter).

I tried searching the net and added

setFileType(FTPClient.BINARY_FILE_TYPE);

But the problem still occurs :(

Could somebody have a look at it and give me a hint or advice ?

Code:

package de.immozukunft.programs;

import java.io.*;
import java.util.Locale;
import java.util.ResourceBundle;

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

/**
 * This class enables the ability to connect and trasfer data to the FTP server
 */

public class FtpUpDown {

    static Locale locale = new Locale("de"); // Locale is set to "de" for
                                                // Germany
    static ResourceBundle r = ResourceBundle.getBundle("Strings", locale); // ResourceBundle
                                                                            // for
                                                                            // different
                                                                            // languages
                                                                            // and
                                                                            // String
                                                                            // Management

    // FTP-Connection properties
    static String host = "IP-address"; //Host
    static String username = "username"; // Username
    static int port = 21; //Port
    static String password = "password"; // Password

    /**
     * <h3>FTP-connection tester</h3>
     * 
     */

    public static boolean connect() {

        FTPClient ftpClient = new FTPClient();

        try {
            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
            ftpClient.connect(host, port);
            ftpClient.login(username, password);
            ftpClient.logout();
            ftpClient.disconnect();
        } catch (Exception e) {
            // e.printStackTrace();
            System.err.println("Unable to connect"); // TODO String einfügen
            return (false);
        }
        System.out.println("Connection established"); // TODO String einfügen
        return (true);
    }

    /**
     * <h3>FTP-Status</h3>
     * 
     * @return
     * @throws IOException
     */
    static public String getStatus() {
        if (connect()) {
            return (r.getString("successConnectFTP"));
        } else {
            return (r.getString("unableToConnectFTP"));
        }
    }

    /**
     * <h3>FTP-filelist</h3>
     * 
     * @return String-Array der Dateinamen auf dem FTP-Server
     */

    public static String[] list() throws IOException {
        FTPClient ftpClient = new FTPClient();
        String[] filenameList;

        try {
            ftpClient.connect(host, port);
            ftpClient.login(username, password);
            filenameList = ftpClient.listNames();
            ftpClient.logout();
        } finally {
            ftpClient.disconnect();
        }

        return filenameList;
    }

    /**
     * <h3>FTP-Client-Download:</h3>
     * 
     * @return true falls ok
     */
    public static boolean download(String localResultFile,
            String remoteSourceFile, boolean showMessages) throws IOException {
        FTPClient ftpClient = new FTPClient();
        FileOutputStream fos = null;
        boolean resultOk = true;

        try {
            ftpClient.connect(host, port);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.login(username, password);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            fos = new FileOutputStream(localResultFile);
            resultOk &= ftpClient.retrieveFile(remoteSourceFile, fos);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.logout();
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
        } finally {
            try {
                if (fos != null) {
                    fos.close();
                }
            } catch (IOException e) {/* nothing to do */
            }
            ftpClient.disconnect();
        }

        return resultOk;
    }

    /**
     * <h3>FTP-Client-Upload:</h3>
     * 
     * @param localSourceFile
     *            The source of local file
     * @param remoteResultFile
     *            Set the destination of the file
     * @param showMessages
     *            If set on TRUE messages will be displayed on the console
     * @return true Returns If successfully transfered it will return TRUE, else
     *         FALSE
     */
    public static boolean upload(String localSourceFile,
            String remoteResultFile, boolean showMessages) throws IOException {

        FTPClient ftpClient = new FTPClient();
        FileInputStream fis = null;
        boolean resultOk = true;

        try {
            ftpClient.connect(host, port);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.login(username, password);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            fis = new FileInputStream(localSourceFile);
            resultOk &= ftpClient.storeFile(remoteResultFile, fis);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.logout();
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
        } finally {
            try {
                if (fis != null) {
                    fis.close();
                }
            } catch (IOException e) {/* nothing to do */
            }
            ftpClient.disconnect();
        }

        return resultOk;
    }

    // Setter and Getter-methods
    public static String getHost() {
        return host;
    }

    public static void setHost(String host) {
        FtpUpDown.host = host;
    }

    public static String getUsername() {
        return username;
    }

    public static void setUsername(String username) {
        FtpUpDown.username = username;
    }

    public static int getPort() {
        return port;
    }

    public static void setPort(int port) {
        FtpUpDown.port = port;
    }

    public static String getPassword() {
        return password;
    }

    public static void setPassword(String password) {
        FtpUpDown.password = password;
    }
}

greets

THE-E

Answer 1

So I finally figured out what the problem was.

The problem was caused by the order of setFileType(FTPClient.BINARY_FILE_TYPE). It needs to be positioned in the upload()-method after the fis = new FileInputStream(localSourceFile) and before the ftpClient.storeFile(remoteResultFile, fis)

So the full working code is:

import java.io.*;
import java.util.Locale;
import java.util.ResourceBundle;

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

/**
 * This class enables the ability to connect and trasfer data to the FTP server
 */

public class FtpUpDown {

    static Locale locale = new Locale("de"); // Locale is set to "de" for
                                                // Germany
    static ResourceBundle r = ResourceBundle.getBundle("Strings", locale); // ResourceBundle
                                                                            // for
                                                                            // different
                                                                            // languages
                                                                            // and
                                                                            // String
                                                                            // Management

    // FTP-Connection properties
    static String host = "IP-Address"; // IP-address
    static String username = "username"; // Username
    static int port = 21; // Port
    static String password = "password"; // Password

    /**
     * <h3>FTP-connection tester</h3>
     * 
     */

    public static boolean connect() {

        FTPClient ftpClient = new FTPClient();

        try {
            ftpClient.connect(host, port);
            ftpClient.login(username, password);
            ftpClient.logout();
            ftpClient.disconnect();
        } catch (Exception e) {
            // e.printStackTrace();
            System.err.println("Unable to connect"); // TODO String einfügen
            return (false);
        }
        System.out.println("Connection established"); // TODO String einfügen
        return (true);
    }

    /**
     * <h3>FTP-Status</h3>
     * 
     * @return
     * @throws IOException
     */
    static public String getStatus() {
        if (connect()) {
            return (r.getString("successConnectFTP"));
        } else {
            return (r.getString("unableToConnectFTP"));
        }
    }

    /**
     * <h3>FTP-filelist</h3>
     * 
     * @return String-Array der Dateinamen auf dem FTP-Server
     */

    public static String[] list() throws IOException {
        FTPClient ftpClient = new FTPClient();
        String[] filenameList;

        try {
            ftpClient.connect(host, port);
            ftpClient.login(username, password);
            filenameList = ftpClient.listNames();
            ftpClient.logout();
        } finally {
            ftpClient.disconnect();
        }

        return filenameList;
    }

    /**
     * <h3>FTP-Client-Download:</h3>
     * 
     * @return true falls ok
     */

    public static boolean download(String localResultFile,
            String remoteSourceFile, boolean showMessages) throws IOException {
        FTPClient ftpClient = new FTPClient();
        FileOutputStream fos = null;
        boolean resultOk = true;

        try {
            ftpClient.connect(host, port);
            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.login(username, password);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            fos = new FileOutputStream(localResultFile);
            resultOk &= ftpClient.retrieveFile(remoteSourceFile, fos);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.logout();
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
        } finally {
            try {
                if (fos != null) {
                    fos.close();
                }
            } catch (IOException e) {/* nothing to do */
            }
            ftpClient.disconnect();
        }

        return resultOk;
    }


    /**
     * <h3>FTP-Client-Upload:</h3>
     * 
     * @param localSourceFile
     *            The source of local file
     * @param remoteResultFile
     *            Set the destination of the file
     * @param showMessages
     *            If set on TRUE messages will be displayed on the console
     * @return true Returns If successfully transfered it will return TRUE, else
     *         FALSE
     */
    public static boolean upload(String localSourceFile,
            String remoteResultFile, boolean showMessages) throws IOException {

        FTPClient ftpClient = new FTPClient();
        FileInputStream fis = null;
        boolean resultOk = true;

        try {
            ftpClient.connect(host, port);

            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.login(username, password);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }

            fis = new FileInputStream(localSourceFile);
            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);

            resultOk &= ftpClient.storeFile(remoteResultFile, fis);
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
            resultOk &= ftpClient.logout();
            if (showMessages) {
                System.out.println(ftpClient.getReplyString());
            }
        } finally {
            try {
                if (fis != null) {
                    fis.close();
                }
                ftpClient.disconnect();
            } catch (IOException e) {/* nothing to do */
            }
        }

        return resultOk;
    }   


    // Setter and Getter-methods
    public static String getHost() {
        return host;
    }

    public static void setHost(String host) {
        FtpUpDown.host = host;
    }

    public static String getUsername() {
        return username;
    }

    public static void setUsername(String username) {
        FtpUpDown.username = username;
    }

    public static int getPort() {
        return port;
    }

    public static void setPort(int port) {
        FtpUpDown.port = port;
    }

    public static String getPassword() {
        return password;
    }

    public static void setPassword(String password) {
        FtpUpDown.password = password;
    }
}

Answer 2

You create a new connection for every operation, and some code paths don't set the "binary file" flag (i.e. the upload and download methods).

Answer 3

setFileType(FTPClient.BINARY_FILE_TYPE) is the right thing to do, but in the code you provided it is only being done in connect(), which isn't called in download().

Even if it was called in download(), disconnect() is called which ends the session.

Bottom line: You need to call setFileType(FTPClient.BINARY_FILE_TYPE) in the download() method and the upload() method after ftpClient.connect(host, port)