我制作了一个ftps客户端阵列，并尝试将其连接到我感兴趣的ip端口。这是密码。

public class ftptest 
{   
    public static void delete_files(String path, int n) throws IOException
    {
        String realpath;
        for(int i=0 ; i<n ; i++)
        {
            realpath = path+i;
            File file = new File(realpath);
            FileUtils.cleanDirectory(file);
        }
    }

    public static void main(String[] args) throws Exception
    {
        int number = 1;
        String ip = "some_ip";
        int port = 990;

        FTPSClient[] client = new FTPSClient[number];

        System.out.println(ip);
        System.out.println("port = "+ port);

        for(int i = 0; i < number; i++)
        {
            String path = "D:\\ftptest\\client"+i;          
            File file = new File(path);
            file.mkdir();       

            client[i] = new FTPSClient(true);   
            client[i].setRemoteVerificationEnabled(false);
            client[i].setTrustManager
            (TrustManagerUtils.getAcceptAllTrustManager());         

            client[i].enterLocalPassiveMode();

            client[i].setControlEncoding("UTF-8");
            client[i].connect(ip,port);

            System.out.println("Connected to " + ip + ".");
        }   
    }
}

但不知怎的，它失败了 client[i].connect(ip, port) 放弃错误
线程“main”java.net.connectexception中出现异常：连接被拒绝：>connect at java.net.dualstackplainsocketimpl.connect0（本机方法）at java.net.dualstackplainsocketimpl.socketconnect（未知源）at java.net.abstractplainsocketimpl.doconnect（未知源）at java.net.abstractplainsocketimpl.connecttoaddress（未知源）java.net.abstractplainsocketimpl.connect（未知源），java.net.plainsocketimpl.connect（未知源），java.net.socksocketImpl.connect（未知源），java.net.socket.connect（未知源），org.apache.commons.net.socketclient.connect（socketclient）。java:182)在org.apache.commons.net.socketclient.connect（socketclient。java:203)在org.apache.commons.net.socketclient.connect（socketclient。java:296)在com.samsung.ftptest.ftptest.main（ftptest。java:66)
当它是ftp而不是ftps时，它工作正常。有人知道它为什么不起作用吗？
谢谢您。