java get fd count. openFileDescriptorCount / maxFileDescriptorCount

pom.xml

	<dependency>
		<groupId>sun.jdk</groupId>
		<artifactId>rt.jar</artifactId>
		<version>1.8</version>
		<scope>system</scope>
		<systemPath>${java.home}/lib/rt.jar</systemPath>
	</dependency>

Test.java

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;

import com.sun.management.UnixOperatingSystemMXBean;

public class Test {

	public static void main(String[] args) {
		OperatingSystemMXBean operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean();
		if (operatingSystemMXBean instanceof UnixOperatingSystemMXBean) {
			UnixOperatingSystemMXBean unixOperatingSystemMXBean = (UnixOperatingSystemMXBean) operatingSystemMXBean;

			System.out.println("maxFileDescriptorCount: " + unixOperatingSystemMXBean.getMaxFileDescriptorCount());
			System.out.println("openFileDescriptorCount: " + unixOperatingSystemMXBean.getOpenFileDescriptorCount());
		}
	}
}