虚拟机实践（九）关于JMX的一些demo

（一）注册一个MBean

/**
     *  注册新的MBean
     */
    @Test
    public void registerMBean() {
        // 获取当前虚拟机使用的 MBean服务器
        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
        try {
            // 注册一个MBean
            server.registerMBean(new HelloWorld(), new ObjectName("domain1:key1=val1"));
            // 再注册一个MBean
            server.registerMBean(new HelloWorld(), new ObjectName("domain1:key2=val2"));
        } catch (InstanceAlreadyExistsException | MBeanRegistrationException | NotCompliantMBeanException
                | MalformedObjectNameException e) {
            e.printStackTrace();
        }
    }

（二）注册一个JMX端口

/**
     * 注册一个新的端口号用于JMX连接
     * @throws Exception
     */
    @Test
    public void restartServer() throws Exception {
        // 新启用一个端口号用于JMX连接
        LocateRegistry.createRegistry(9999);
        JMXConnectorServer jcs = JMXConnectorServerFactory.newJMXConnectorServer(
                new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:9999/jmxrmi"), 
                null, 
                ManagementFactory.getPlatformMBeanServer());
        jcs.start();
    }

（三）客户端代码

/**
     *  客户端代码
     * @throws Exception 
     */
    @Test
    public void mbeanClient() throws Exception {
        //connect JMX  
        JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:9999/jmxrmi");  
        JMXConnector connector = JMXConnectorFactory.connect(url,null);  
        // 获取JMX连接
        MBeanServerConnection conn = connector.getMBeanServerConnection();       
           
        // 获取所有域名
        String domains[] = conn.getDomains();
        for (int i = 0; i < domains.length; i++) {         
            System.out.println("Domain[" + i +"] = " + domains[i]);      
        }
        
        // 获取 MBean的个数 
        System.out.println("MBean count = " + conn.getMBeanCount()); 
        
        // 获取所有MBean
        Set<ObjectInstance> set = conn.queryMBeans(null, null);  
        for (Iterator<ObjectInstance> it = set.iterator(); it.hasNext();) {  
            ObjectInstance oi = it.next();          
            System.out.println(oi.getObjectName());          
        }   
        
        ObjectName name = new ObjectName("domain1:key1=val1");     
        // 获取一个ObjectName对应的基本信息:MBeanInfo
        MBeanInfo info = conn.getMBeanInfo(name);           
        System.out.println("Class:" + info.getClassName());        
        System.out.println("Attribute:" + info.getAttributes()[0].getName());       
        System.out.println("Operation:" + info.getOperations()[0].getName());     
        
        // 修改MBean属性的方式（一）
        conn.setAttribute(name, new Attribute("Greeting", "JOHNLIUISMINE"));
        conn.getAttribute(name, "Greeting"); 
           
        // 修改MBean属性的方式（二）通过动态代理 ObjectName
        HelloWorldMBean proxy = (HelloWorldMBean) MBeanServerInvocationHandler.newProxyInstance(conn, name, HelloWorldMBean.class, false);          
        proxy.setGreeting("nice to meet u client");
        proxy.getGreeting(); 
           
        // 修改MBean属性的方式（三）通过invoke
        System.out.println(conn.invoke(name, "printGreeting", null, null));           
           
        // 关闭连接
        connector.close();     
    }