下面的步骤应该可以得到CPU和RAM。有关更多细节，请参阅管理工厂。

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

private static void printUsage() {
  OperatingSystemMXBean operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean();
  for (Method method : operatingSystemMXBean.getClass().getDeclaredMethods()) {
    method.setAccessible(true);
    if (method.getName().startsWith("get")
        && Modifier.isPublic(method.getModifiers())) {
            Object value;
        try {
            value = method.invoke(operatingSystemMXBean);
        } catch (Exception e) {
            value = e;
        } // try
        System.out.println(method.getName() + " = " + value);
    } // if
  } // for
}

下面的步骤应该可以得到CPU和RAM。有关更多细节，请参阅管理工厂。

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

private static void printUsage() {
  OperatingSystemMXBean operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean();
  for (Method method : operatingSystemMXBean.getClass().getDeclaredMethods()) {
    method.setAccessible(true);
    if (method.getName().startsWith("get")
        && Modifier.isPublic(method.getModifiers())) {
            Object value;
        try {
            value = method.invoke(operatingSystemMXBean);
        } catch (Exception e) {
            value = e;
        } // try
        System.out.println(method.getName() + " = " + value);
    } // if
  } // for
}

在JDK 1.7中，你可以通过com.sun.management.OperatingSystemMXBean获取系统CPU和内存的使用情况。这与java.lang.management.OperatingSystemMXBean不同。

long getCommittedVirtualMemorySize()
// Returns the amount of virtual memory that is guaranteed to be available to the running process in bytes, or -1 if this operation is not supported.

long getFreePhysicalMemorySize()
// Returns the amount of free physical memory in bytes.

long getFreeSwapSpaceSize()
// Returns the amount of free swap space in bytes.

double getProcessCpuLoad()
// Returns the "recent cpu usage" for the Java Virtual Machine process.

long getProcessCpuTime()
// Returns the CPU time used by the process on which the Java virtual machine is running in nanoseconds.

double getSystemCpuLoad()
// Returns the "recent cpu usage" for the whole system.

long getTotalPhysicalMemorySize()
// Returns the total amount of physical memory in bytes.

long getTotalSwapSpaceSize()
// Returns the total amount of swap space in bytes.

这对我来说是完美的，没有任何外部API，只是本地Java隐藏功能:)

import com.sun.management.OperatingSystemMXBean;
...
OperatingSystemMXBean osBean = ManagementFactory.getPlatformMXBean(
                OperatingSystemMXBean.class);
// What % CPU load this current JVM is taking, from 0.0-1.0
System.out.println(osBean.getProcessCpuLoad());

// What % load the overall system is at, from 0.0-1.0
System.out.println(osBean.getSystemCpuLoad());

    OperatingSystemMXBean osBean = ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class);
    System.out.println((osBean.getCpuLoad() * 100) + "%");

进口com.sun.management.OperatingSystemMXBean

它只在第二次调用后开始工作，因此保存osBean并将其放入循环中

来看看这篇非常详细的文章: http://nadeausoftware.com/articles/2008/03/java_tip_how_get_cpu_and_user_time_benchmarking#UsingaSuninternalclasstogetJVMCPUtime

要得到CPU使用的百分比，你只需要做一些简单的数学运算:

MBeanServerConnection mbsc = ManagementFactory.getPlatformMBeanServer();

OperatingSystemMXBean osMBean = ManagementFactory.newPlatformMXBeanProxy(
mbsc, ManagementFactory.OPERATING_SYSTEM_MXBEAN_NAME, OperatingSystemMXBean.class);

long nanoBefore = System.nanoTime();
long cpuBefore = osMBean.getProcessCpuTime();

// Call an expensive task, or sleep if you are monitoring a remote process

long cpuAfter = osMBean.getProcessCpuTime();
long nanoAfter = System.nanoTime();

long percent;
if (nanoAfter > nanoBefore)
 percent = ((cpuAfter-cpuBefore)*100L)/
   (nanoAfter-nanoBefore);
else percent = 0;

System.out.println("Cpu usage: "+percent+"%");

注意:您必须导入com.sun.management.OperatingSystemMXBean，而不是java.lang.management.OperatingSystemMXBean。