JMX

In-process use code to get
public static void test() throws Exception {
		MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
		ObjectName objectName = new ObjectName("java.nio:type=BufferPool,name=direct");
		MBeanInfo info = mbs.getMBeanInfo(objectName);
		for (MBeanAttributeInfo i : info.getAttributes()) {
			System.out.println(i.getName() + ":" + mbs.getAttribute(objectName, i.getName()));
		}
	}

remote process
JMX get
If the target machine does not have JMX enabled, then add the jvm parameter:
-Dcom.sun.management.jmxremote.port=9999 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremotAe.ssl=false
restart process
The machine is then accessed via a JMX connection:
public static void test02() throws Exception {
		String jmxURL = "service:jmx:rmi:///jndi/rmi://127.0.0.1:9999/jmxrmi";
		JMXServiceURL serviceURL = new JMXServiceURL(jmxURL);
		Map<String, String[]> map = new HashMap<>();
		String[] credentials = new String[] { "monitorRole", "QED" };
		map.put("jmx.remote.credentials", credentials);
		JMXConnector connector = JMXConnectorFactory.connect(serviceURL, map);
		MBeanServerConnection mbsc = connector.getMBeanServerConnection();
		ObjectName objectName = new ObjectName("java.nio:type=BufferPool,name=direct");
		MBeanInfo mbInfo = mbsc.getMBeanInfo(objectName);
		for (MBeanAttributeInfo i : mbInfo.getAttributes()) {
			System.out.println(i.getName() + ":" + mbsc.getAttribute(objectName, i.getName()));
		}
	}