JMX浅谈

一 JMX 是什么？

JMX(Java Management Extensions，即Java管理扩展)

JMX在Java编程语言中定义了应用程序以及网络管理和监控的体系结构、设计模式、应用程序接口以及服务。通常使用JMX来监控系统的运行状态或管理系统的某些方面，比如清空缓存、重新加载配置文件等

优点可以非常容易的使应用程序具有被管理

伸缩性的架构每个JMX Agent服务可以很容易的放入到Agent中，每个JMX的实现都提供几个核心的Agent服务，你也可以自己编写服务，服务可以很容易的部署，取消部署。

主要提供接口，允许有不同的实现
二 JMX 实例分析
分为服务器端和客户端
服务器端
Monitor.java

public class Monitor {
    public Monitor(){
        
    }
    public static void main(String[] args) {
        start();
    }
 
    public static void start() {
        new Thread(new Runnable() {
            public void run() {

                Thread.currentThread().setContextClassLoader(Monitor.class.getClassLoader());
                 
                MBeanServer server = ManagementFactory.getPlatformMBeanServer();
                ObjectName memory;
                try {
                    
                    memory = new ObjectName(Constants.MEMORY_MANAGE_BEAN);
                    //注册待监控Object class
                    server.registerMBean(new MemoryManager(), memory);
                    //监控端口
                    int serverPort = Constants.MONITOR_SERVANT_PORT;
                    
                    LocateRegistry.createRegistry(serverPort);
                    
                    JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:" + serverPort + "/jmxrmi");
                    JMXConnectorServer cs = JMXConnectorServerFactory.newJMXConnectorServer(url, null, server);
                    cs.start();
                    
                    System.out.println("----jmx server start ----- ");
                } catch (Exception e) {
                    System.out.println("----Fail to start server----");
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

被调用类

接口MemoryManagerMXBean.java

public interface MemoryManagerMXBean {
    public void stop();  
 
    public long getTotalPhysicalMemorySize(int mask);
    
    public static class MemoryStateMask{
        public static final int OVERALL_MEMORY_USE = 1;  
        public static final int TYPE_ALLTIME_MEMORY_USE = 2;  /
    }

    public String getMemoryState(int memoryStateMask);
}

MemoryManager.java

public class MemoryManager implements MemoryManagerMXBean{    
    public MemoryManager(){ 
    } 
    @Override
    public String getMemoryState(int mask) {
        String result = "";
        switch(mask){
        case MemoryStateMask.OVERALL_MEMORY_USE:  
            result = getOverallMemoryState(); 
            break;
        case MemoryStateMask.TYPE_ALLTIME_MEMORY_USE:
            result = MonitorRuntime.getTypeMemoryUse(MonitorRuntime.TYPE_MEMORY_USE_OPTION.ALLTIME_USE);
            break;
        } 
        
        return result;
    } 
 private long getUsedMemory(){
        Runtime rt = Runtime.getRuntime();
        long usedMem = rt.totalMemory() - rt.freeMemory();
        return usedMem;
    }
}
 

客户端调用：
JmxWebContainerConnector.java

public class JmxWebContainerConnector {
    private MBeanServerConnection mbsc;
    private ObjectName mbeanName;
    public JmxWebContainerConnector() throws Exception {
        try {
            int serverPort = Constants.MONITOR_SERVANT_PORT;
            JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:" + serverPort + "/jmxrmi");
            JMXConnector jmxc = JMXConnectorFactory.connect(url, null);
            this.mbsc = jmxc.getMBeanServerConnection();
            this.mbeanName = new ObjectName(Constants.MEMORY_MANAGE_BEAN);
        } catch (Exception e) {
            System.err.println("。。。。连接服务器失败。。。。");
            throw new Exception(e);
        }
    }public MemoryState getMemoryState() throws Exception {
        int overallMemoryUseMask = 1;
        String json = (String) mbsc.invoke(mbeanName, "getMemoryState", new Object[] { overallMemoryUseMask }, new String[] { "int" });
        MemoryState state = MemoryState.fromJmxJSON(json);
        return state;
    }
    
}