ftp4j：client.login返回无法识别的SSL消息，纯文本连接？

Question

这是我的代码

try{
    TrustManager[] trustManager = new TrustManager[] { new X509TrustManager() {
        public X509Certificate[] getAcceptedIssuers() { return null; }
        public void checkClientTrusted(X509Certificate[] certs, String authType) {}
        public void checkServerTrusted(X509Certificate[] certs, String authType) {}
    } };

    SSLContext sslContext = null;

    sslContext = SSLContext.getInstance("TLS");
    sslContext.init(null, trustManager, new SecureRandom());
    SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory();
    FTPClient client = new FTPClient();

    client.setSSLSocketFactory(sslSocketFactory);
    client.setSecurity(FTPClient.SECURITY_FTPES);

    client.connect("xxx.xxx.xxx", 21);
    System.out.println("Connected (" + client.isConnected() + ") to host " + client.getHost() + ":" + client.getPort());
    client.login("xxxxx", "xxxxx");            
}catch (Exception e) {
    e.printStackTrace();
}

运行时返回

Connected (true) to host xxx.xxx.xxx:21

然后在client.login（“ xxxxx”，“ xxxxx”）;上断开 有例外

javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?

知道为什么会这样吗？

Java版本是1.4.2，ftp4j版本是1.7.2

Answer 1

消息很清楚。 您正在与纯文本对等方通信。 该主机的端口21上确实有一个FTPS服务器吗？

Answer 2

请确保使用正确的安全设置，例如FTPClient.SECURITY_FTPS或FTPClient.SECURITY_FTPES

FTPS（基于隐式TLS / SSL的FTP）和FTPES（基于显式TLS / SSL的FTP）