java - FTPClient下载文件失败，retrieveFile()方法replyCode = 550

/ *
我在localhost上运行FTP服务器。当我使用ftpClient.retrieveFile()方法下载文件时，其ReplyCode为550。我阅读了commons-net的API并找到了550 ReplyCode，其定义为“public static final int FILE_UNAVAILABLE 550”。但是我无法从代码中找到问题。
谢谢你的帮助。

* /

    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);
        }
    }

最佳答案

我发现Apache RetrieveFile(...)有时无法使用超过特定限制的文件大小。为了克服这个问题，我将改用retrieveFileStream()。在下载之前，我已经设置了正确的FileType并将Mode设置为PassiveMode

所以代码看起来像

    ....
    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();
    ....