小编Jot*_*taB的帖子

每次尝试连接时，都会收到异常“连接未打开”。当我尝试通过 FileZilla 或浏览器访问时，服务器运行良好。

我正在使用 apache-common-net 库。

private Boolean downloadAndSaveFile(String server, int portNumber,
                                    String user, String password, String filename, File localFile)
        throws IOException {
    FTPClient ftp = null;

    try {
        ftp = new FTPClient();
        ftp.connect(server, portNumber);

        ftp.login(user, password);

        ftp.setFileType(FTP.BINARY_FILE_TYPE);

        ftp.enterLocalPassiveMode();

        OutputStream outputStream = null;
        boolean success = false;
        try {
            outputStream = new BufferedOutputStream(new FileOutputStream(
                    localFile));
            success = ftp.retrieveFile(filename, outputStream);
        } finally {
            if (outputStream != null) {
                outputStream.close();
            }
        }

        return success;
    } finally {
        if (ftp != null) { …