java - Apache ftp.retrieveFileStream 返回 null

Question

如何使用 apache.commons 从 FTP 下载文件，这是我一直在尝试做的事情:

    ftp = new FTPClient();
    ftp.connect("my.remote");
    ftp.login("username", "password");

    String ftpPath = "/my/file/file.data";
    ftp.setFileTransferMode(FTPClient.BLOCK_TRANSFER_MODE);
    ftp.setFileType(FTP.BINARY_FILE_TYPE);
    System.out.println(ftp.mlistFile(ftpPath));
    InputStream inputStream = ftp.retrieveFileStream(ftpPath);
    if (inputStream == null) {
        System.out.println("Error " + " " + ftp.getReplyCode() +
        " " + ftp.getReplyString());
        return;
    }

但是它给了我一个错误，输出如下。如果我在同一台机器上使用 FileZilla，它确实可以工作

ype=file;Size=33130206;Modify=20170207225217;Perm=adfrw; file.data main
Error 500 500 Illegal PORT command

Answer 1

首先，你确定是FTP而不是FTPS吗？ 其中一部分，尝试使用以下代码:

ftp = new FTPClient();
    ftp.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
    int reply;
    ftp.connect(host,numPort); //if you have not port number, use only host
    reply = ftp.getReplyCode();
    if (!FTPReply.isPositiveCompletion(reply)) {
        ftp.disconnect();
        System.out.println("Error");
    }
    ftp.login(user, pwd);
    ftp.setFileType(ftp.BINARY_FILE_TYPE);
    ftp.enterLocalPassiveMode();
    ftp.printWorkingDirectory(); //print workingdirectory
    ftp.changeWorkingDirectory("/work"); //change directory
    ftp.printWorkingDirectory();
    FTPFile[] files1 = ftp.listFiles();
    for (FTPFile file : files) {
        String details = file.getName();
        Calendar dateOfmyFile=file.getTimestamp();
        boolean isaDir=false;
        if (file.isDirectory()) {
            details = "[" + details + "]";
            isaDir=true;
        }
        else{
           downloadFile(host+details, mylocalFilePath);
          }
       }
public void downloadFile(String remoteFilePath, String localFilePath) throws IOException {
    FileOutputStream fos = null;
    ftp.printWorkingDirectory();
    try {
        fos =new FileOutputStream(localFilePath);
        ftp.retrieveFile(remoteFilePath,fos);
        fos.close();

    } catch (IOException e) {
        e.printStackTrace();
    }
}