JAVA编写FTP连接报错java.net.ConnectException: Connection refused: connect FTP

代码如下：
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import sun.net.TelnetOutputStream;
import sun.net.TelnetInputStream;
import sun.net.ftp.FtpClient;

public class FtpTest {
String localfilename;

String remotefilename;

FtpClient ftpClient;

// server：服务器名字
// user：用户名
// password：密码
// path：服务器上的路径
public void connectServer(String ip, int port,String user
, String password,String path) {

try {
ftpClient = new FtpClient();
ftpClient.openServer(ip,port);
ftpClient.login(user, password);
System.out.println("login success!");
if (path.length() != 0) ftpClient.cd(path);
ftpClient.binary();
} catch (IOException ex) {
System.out.println("not login");
System.out.println(ex);
}
}

public void closeConnect() {
try {
ftpClient.closeServer();
System.out.println("disconnect success");
} catch (IOException ex) {
System.out.println("not disconnect");
System.out.println(ex);
}
}

public static void main(String agrs[]) {

FtpTest ft = new FtpTest();
//以连接本机做测试
ft.connectServer("127.0.0.1",21, "实际的账号", "实际密码","/");
}
}
错误提示：

not login
java.net.ConnectException: Connection refused: connect

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