下面的代码只适用于Linux(可能是Unix)，但它可以在实际项目中工作。

    private double getAverageValueByLinux() throws InterruptedException {
    try {

        long delay = 50;
        List<Double> listValues = new ArrayList<Double>();
        for (int i = 0; i < 100; i++) {
            long cput1 = getCpuT();
            Thread.sleep(delay);
            long cput2 = getCpuT();
            double cpuproc = (1000d * (cput2 - cput1)) / (double) delay;
            listValues.add(cpuproc);
        }
        listValues.remove(0);
        listValues.remove(listValues.size() - 1);
        double sum = 0.0;
        for (Double double1 : listValues) {
            sum += double1;
        }
        return sum / listValues.size();
    } catch (Exception e) {
        e.printStackTrace();
        return 0;
    }

}

private long getCpuT throws FileNotFoundException, IOException {
    BufferedReader reader = new BufferedReader(new FileReader("/proc/stat"));
    String line = reader.readLine();
    Pattern pattern = Pattern.compile("\\D+(\\d+)\\D+(\\d+)\\D+(\\d+)\\D+(\\d+)")
    Matcher m = pattern.matcher(line);

    long cpuUser = 0;
    long cpuSystem = 0;
    if (m.find()) {
        cpuUser = Long.parseLong(m.group(1));
        cpuSystem = Long.parseLong(m.group(3));
    }
    return cpuUser + cpuSystem;
}

    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

通过JMX已经可以获得其中的许多功能。在Java 5中，JMX是内置的，并且包含了一个带有JDK的JMX控制台查看器。

您可以使用JMX进行手动监视，如果在自己的运行时需要这些信息，也可以从Java调用JMX命令。

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.

2008年被接受的答案推荐了SIGAR。然而，正如2014年(@Alvaro)的评论所说:

使用Sigar时要小心，在x64机器上有问题… Sigar 1.6.4正在崩溃:EXCEPTION_ACCESS_VIOLATION，似乎库 从2010年开始就没更新过

我的建议是使用https://github.com/oshi/oshi

或者上面提到的答案。

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());