■ はじめに

の続き。

【1】コマンドを実行した場合

 * vmstatコマンドでJavaコードから実行し、CPU情報を抽出する

サンプル

【2】com.sun.management.OperatingSystemMXBean を使った方法

サンプル

import java.lang.management.ManagementFactory;

public class Main {
  @SuppressWarnings("restriction")
  public static void main(String[] args) {
    com.sun.management.OperatingSystemMXBean operatingSystemMXBean =
        (com.sun.management.OperatingSystemMXBean) ManagementFactory.getOperatingSystemMXBean();
     System.out.println("ProcessCpuLoad : " + operatingSystemMXBean.getProcessCpuLoad());
     System.out.println("ProcessCpuTime : " + operatingSystemMXBean.getProcessCpuTime());
     System.out.println("SystemCpuTime : " + operatingSystemMXBean.getSystemCpuLoad());
  }
}

ProcessCpuLoad : -1.0
ProcessCpuTime : 421875000
SystemCpuTime : -1.0

【3】MBeanServer を使った方法

サンプル

import java.lang.management.ManagementFactory;
import javax.management.Attribute;
import javax.management.AttributeList;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;
import javax.management.ReflectionException;

public class Main {
  public static void main(String[] args) throws Exception {
    printCpuInfo();
  }

  public static void printCpuInfo()
      throws InstanceNotFoundException, ReflectionException, MalformedObjectNameException, NullPointerException {
    MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
    ObjectName objectName = ObjectName.getInstance("java.lang:type=OperatingSystem");
    AttributeList attributeList = mbeanServer.getAttributes(objectName,
        new String[] { "ProcessCpuLoad", "ProcessCpuTime", "SystemCpuLoad" });

    if (attributeList.isEmpty()) {
      System.out.println("attributeList is Empty");
    }

    for (Attribute attribute : attributeList.asList()) {
      System.out.println(attribute.getName() + " : " + attribute.getValue());
    }
  }
}

ProcessCpuLoad : 0.37238200554819395
ProcessCpuTime : 578125000
SystemCpuLoad : -1.0

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

public class Main {
  public static void main(String[] args) {
    printUsage();
  }

  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 ex) {
          value = ex;
        }
        System.out.println(method.getName() + " = " + value);
      }
    }
  }
}

getCommittedVirtualMemorySize = 236544000
getFreePhysicalMemorySize = 2628100096
getFreeSwapSpaceSize = 2142429184
getProcessCpuLoad = -1.0
getProcessCpuTime = 515625000
getSystemCpuLoad = -1.0
getTotalPhysicalMemorySize = 8491581440
getTotalSwapSpaceSize = 10035085312

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