FTPClient download file failed，the retrieveFile() method replyCode=550

Question

/* I run a FTP server on localhost.when I download files use ftpClient.retrieveFile() method,it's replyCode is 550 . I read the API of commons-net and find the 550 replyCode,the defines is" public static final int FILE_UNAVAILABLE 550".but I cannot find the problem from my codes.
thanks for your help.

*/

    FTPClient ftpClient = new FTPClient();
    FileOutputStream fos = null;

    try {
        ftpClient.connect("192.168.1.102",2121);
        ftpClient.login("myusername", "12345678");
        ftpClient.setControlEncoding("UTF-8");
        ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
        String remoteFileName = "ftpserver.zip";//this file in the rootdir
        fos = new FileOutputStream("f:/down.zip");
        ftpClient.setBufferSize(1024);
        ftpClient.enterLocalPassiveMode();
        ftpClient.enterLocalActiveMode();
        ftpClient.retrieveFile(remoteFileName, fos);  
        System.out.println("retrieveFile?"+ftpClient.getReplyCode());
        fos.close();
        ftpClient.logout();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            ftpClient.disconnect();
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException("关闭FTP异常", e);
        }
    }

Answer 1

I found that Apache retrieveFile(...) sometimes did not work with File Sizes exceeding a certain limit. To overcome that I would used retrieveFileStream() instead. Prior to download I have set the Correct FileType and set the Mode to PassiveMode

So the code will look like

    ....
    ftpClientConnection.setFileType(FTP.BINARY_FILE_TYPE);
    ftpClientConnection.enterLocalPassiveMode();
    ftpClientConnection.setAutodetectUTF8(true);

    //Create an InputStream to the File Data and use FileOutputStream to write it
    InputStream inputStream = ftpClientConnection.retrieveFileStream(ftpFile.getName());
    FileOutputStream fileOutputStream = new FileOutputStream(directoryName + "/" + ftpFile.getName());
    //Using org.apache.commons.io.IOUtils
    IOUtils.copy(inputStream, fileOutputStream);
    fileOutputStream.flush();
    IOUtils.closeQuietly(fileOutputStream);
    IOUtils.closeQuietly(inputStream);
    boolean commandOK = ftpClientConnection.completePendingCommand();
    ....