java.lang.management 包概述

public class ManagementDemo {

    public static void main(String[] args) {
        showJvmInfo();
        showMemoryInfo();
        showSystem();
        showClassLoading();
        showCompilation();
        showThread();
        showGarbageCollector();
        showMemoryManager();
        showMemoryPool();
    }

    /**
     * Java 虚拟机的运行时系统
     */
    public static void showJvmInfo() {
        RuntimeMXBean mxbean = ManagementFactory.getRuntimeMXBean();
        String vendor = mxbean.getVmVendor();
        System.out.println("jvm name:" + mxbean.getVmName());
        System.out.println("jvm version:" + mxbean.getVmVersion());
        System.out.println("jvm bootClassPath:" + mxbean.getBootClassPath());
        System.out.println("jvm start time:" + mxbean.getStartTime());
    }

    /**
     * Java 虚拟机的内存系统
     */
    public static void showMemoryInfo() {
        MemoryMXBean mem = ManagementFactory.getMemoryMXBean();
        MemoryUsage heap = mem.getHeapMemoryUsage();
        System.out.println("Heap committed:" + heap.getCommitted() + " init:" + heap.getInit() + " max:" + heap.getMax()
                + " used:" + heap.getUsed());
    }

    /**
     * Java 虚拟机在其上运行的操作系统
     */
    public static void showSystem() {
        OperatingSystemMXBean op = ManagementFactory.getOperatingSystemMXBean();
        System.out.println("Architecture: " + op.getArch());
        System.out.println("Processors: " + op.getAvailableProcessors());
        System.out.println("System name: " + op.getName());
        System.out.println("System version: " + op.getVersion());
        System.out.println("Last minute load: " + op.getSystemLoadAverage());
    }

    /**
     * Java 虚拟机的类加载系统
     */
    public static void showClassLoading() {
        ClassLoadingMXBean cl = ManagementFactory.getClassLoadingMXBean();
        System.out.println("TotalLoadedClassCount: " + cl.getTotalLoadedClassCount());
        System.out.println("LoadedClassCount" + cl.getLoadedClassCount());
        System.out.println("UnloadedClassCount:" + cl.getUnloadedClassCount());
    }

    /**
     * Java 虚拟机的编译系统
     */
    public static void showCompilation() {
        CompilationMXBean com = ManagementFactory.getCompilationMXBean();
        System.out.println("TotalCompilationTime:" + com.getTotalCompilationTime());
        System.out.println("name:" + com.getName());
    }

    /**
     * Java 虚拟机的线程系统
     */
    public static void showThread() {
        ThreadMXBean thread = ManagementFactory.getThreadMXBean();
        System.out.println("ThreadCount" + thread.getThreadCount());
        System.out.println("AllThreadIds:" + thread.getAllThreadIds());
        System.out.println("CurrentThreadUserTime" + thread.getCurrentThreadUserTime());
        // ......还有其他很多信息
    }

    /**
     * Java 虚拟机中的垃圾回收器。
     */
    public static void showGarbageCollector() {
        List<GarbageCollectorMXBean> gc = ManagementFactory.getGarbageCollectorMXBeans();
        for (GarbageCollectorMXBean GarbageCollectorMXBean : gc) {
            System.out.println("name:" + GarbageCollectorMXBean.getName());
            System.out.println("CollectionCount:" + GarbageCollectorMXBean.getCollectionCount());
            System.out.println("CollectionTime" + GarbageCollectorMXBean.getCollectionTime());
        }
    }

    /**
     * Java 虚拟机中的内存管理器
     */
    public static void showMemoryManager() {
        List<MemoryManagerMXBean> mm = ManagementFactory.getMemoryManagerMXBeans();
        for (MemoryManagerMXBean eachmm : mm) {
            System.out.println("name:" + eachmm.getName());
            System.out.println("MemoryPoolNames:" + eachmm.getMemoryPoolNames().toString());
        }
    }

    /**
     * Java 虚拟机中的内存池
     */
    public static void showMemoryPool() {
        List<MemoryPoolMXBean> mps = ManagementFactory.getMemoryPoolMXBeans();
        for (MemoryPoolMXBean mp : mps) {
            System.out.println("name:" + mp.getName());
            System.out.println("CollectionUsage:" + mp.getCollectionUsage());
            System.out.println("type:" + mp.getType());
        }
    }

    /**
     * 访问 MXBean 的方法的三种方法
     */
    public static void visitMBean() {
        // 第一种直接调用同一 Java 虚拟机内的 MXBean 中的方法。
        RuntimeMXBean mxbean = ManagementFactory.getRuntimeMXBean();
        String vendor1 = mxbean.getVmVendor();
        System.out.println("vendor1:" + vendor1);

        // 第二种通过一个连接到正在运行的虚拟机的平台 MBeanServer 的 MBeanServerConnection。
        MBeanServerConnection mbs = null;
        // Connect to a running JVM (or itself) and get MBeanServerConnection
        // that has the JVM MXBeans registered in it

        try { // Assuming the RuntimeMXBean has been registered in mbs ObjectName
            oname = new ObjectName(ManagementFactory.RUNTIME_MXBEAN_NAME);
            String vendor2 = (String) mbs.getAttribute(oname, "VmVendor");
            System.out.println("vendor2:" + vendor2);
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 第三种使用 MXBean 代理
        MBeanServerConnection mbs3 = null;
        RuntimeMXBean proxy;
        try {
            proxy = ManagementFactory.newPlatformMXBeanProxy(mbs3, ManagementFactory.RUNTIME_MXBEAN_NAME,
                    RuntimeMXBean.class);
            String vendor = proxy.getVmVendor();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}