How to get percentage of CPU usage of OS from java

问题

I want to calculate percentage of CPU usage of OS from java code.

There are several ways to find it by unix command [e.g. using mpstat, /proc/stat etc...] and use it from Runtime.getRuntime().exec

But I don\'t want to use the system calls.

I tried ManagementFactory.getOperatingSystemMXBean()

OperatingSystemMXBean osBean =
         (OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
System.out.println(osBean.getSystemLoadAverage());

But it gives the cpu load but not the cpu usage. Is there anyway to find the usage percentage?

回答1:

In Java 7 you can get it like so:

public static double getProcessCpuLoad() throws Exception {

    MBeanServer mbs    = ManagementFactory.getPlatformMBeanServer();
    ObjectName name    = ObjectName.getInstance("java.lang:type=OperatingSystem");
    AttributeList list = mbs.getAttributes(name, new String[]{ "ProcessCpuLoad" });

    if (list.isEmpty())     return Double.NaN;

    Attribute att = (Attribute)list.get(0);
    Double value  = (Double)att.getValue();

    // usually takes a couple of seconds before we get real values
    if (value == -1.0)      return Double.NaN;
    // returns a percentage value with 1 decimal point precision
    return ((int)(value * 1000) / 10.0);
}

回答2:

You can use the SIGAR API. It is cross platform ( but I've only use it on Windows).

The Javadoc is available here and the binaries are here

It is licensed under the terms of the Apache 2.0 license.

来源：https://stackoverflow.com/questions/18489273/how-to-get-percentage-of-cpu-usage-of-os-from-java

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