如何使用Java和JMX获得Tomcat正常运行时间

我想使用Java使用JMX监视Tomcat8。我测试了这段代码：

private MBeanServerConnection connection;
    private JMXConnector connector;

    @Test
    public void testOne() throws Exception
    {
        try
        {
            System.out.println("Starting lookup ...");

            ObjectName mBeanName = new ObjectName("java.lang:type=Runtime");
            String attributeName = "StartTime";

            String host = "51.29.7.12";
            int port = 9999;  // management-native port

            HashMap environment = new HashMap();
            String[] credentials = new String[]
            {
                "admin", "admin"
            };
            environment.put(JMXConnector.CREDENTIALS, credentials);
            String urlString = System.getProperty("jmx.service.url", "service:jmx:remoting-jmx://" + host + ":" + port);
            JMXServiceURL serviceURL = new JMXServiceURL(urlString);
            connector = JMXConnectorFactory.connect(serviceURL, null);
            connection = connector.getMBeanServerConnection();

            Object attrVal = connection.getAttribute(mBeanName, attributeName);
            System.out.println("Value via JMX: " + new Date((Long) attrVal));
            connector.close();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

    }

但我收到消息

java.io.IOException:操作失败，状态为等待

使用JMX连接到远程Tomcat服务器的正确方法是什么