Java SE 6 新特性: JMX 与系统管理

package standardbeans; 
public class ServerImpl { 
    public final long startTime; 
    public ServerImpl() { 
        startTime = System.currentTimeMillis(); 
    } 
} 

package standardbeans; 
public class ServerMonitor implements ServerMonitorMBean { 
    private final ServerImpl target; 
    public ServerMonitor(ServerImpl target){ 
        this.target = target; 
    } 
    public long getUpTime(){ 
        return System.currentTimeMillis() - target.startTime; 
    } 
} 

package standardbeans; 
import javax.management.MBeanServer; 
import javax.management.MBeanServerFactory; 
import javax.management.ObjectName; 
public class Main { 
    private static ObjectName objectName ; 
    private static MBeanServer mBeanServer; 
    public static void main(String[] args) throws Exception{ 
        init(); 
        manage();                
    } 
    private static void init() throws Exception{ 
        ServerImpl serverImpl = new ServerImpl(); 
        ServerMonitor serverMonitor = new ServerMonitor(serverImpl); 
        mBeanServer = MBeanServerFactory.createMBeanServer(); 
        objectName = new ObjectName("objectName:id=ServerMonitor1"); 
        mBeanServer.registerMBean(serverMonitor,objectName);   
    } 
    private static void manage() throws Exception{ 
        Long upTime = (Long) mBeanServer.getAttribute(objectName, 
        "upTime"); 
        System.out.println(upTime); 
    }  
} 

package dynamicbeans; 

import javax.management.*; 
import java.lang.reflect.*; 
public class ServerMonitor implements DynamicMBean { 
  
    private final ServerImpl target;     
    private MBeanInfo mBeanInfo;     
         
    public ServerMonitor(ServerImpl target){ 
        this.target = target; 
    } 
     
    //实现获取被管理的 ServerImpl 的 upTime 
    public long upTime(){ 
        return System.currentTimeMillis() - target.startTime; 
    } 

 //javax.management.MBeanServer 会通过查询 getAttribute("Uptime") 获得 "Uptime" 属性值 
    public Object getAttribute(String attribute) throws AttributeNotFoundException,  
  MBeanException, ReflectionException { 
        if(attribute.equals("UpTime")){ 
            return upTime(); 
        } 
        return null; 
    } 
  
 //给出 ServerMonitor 的元信息。   
    public MBeanInfo getMBeanInfo() { 
        if (mBeanInfo == null) { 
            try { 
                Class cls = this.getClass(); 
                //用反射获得 "upTime" 属性的读方法 
                Method readMethod = cls.getMethod("upTime", new Class[0]);  
                //用反射获得构造方法 
                Constructor constructor = cls.getConstructor(new Class[] 
     {ServerImpl.class}); 
                //关于 "upTime" 属性的元信息:名称为 UpTime，只读属性(没有写方法)。 
                MBeanAttributeInfo upTimeMBeanAttributeInfo = new MBeanAttributeInfo( 
                        "UpTime", "The time span since server start", 
                        readMethod, null); 
                //关于构造函数的元信息 
                MBeanConstructorInfo mBeanConstructorInfo = new MBeanConstructorInfo( 
                        "Constructor for ServerMonitor", constructor); 
                //ServerMonitor 的元信息，为了简单起见，在这个例子里， 
                //没有提供 invocation 以及 listener 方面的元信息  
                mBeanInfo = new MBeanInfo(cls.getName(), 
                        "Monitor that controls the server", 
                        new MBeanAttributeInfo[] { upTimeMBeanAttributeInfo }, 
                        new MBeanConstructorInfo[] { mBeanConstructorInfo }, 
                        null, null);                 
            } catch (Exception e) { 
                throw new Error(e); 
            } 

        } 
        return mBeanInfo; 
    } 

    public AttributeList getAttributes(String[] arg0) {         
        return null; 
    } 
         
    public Object invoke(String arg0, Object[] arg1, String[] arg2)  
  throws MBeanException,  
  ReflectionException {         
        return null; 
    } 

    public void setAttribute(Attribute arg0) throws AttributeNotFoundException,  
  InvalidAttributeValueException, MBeanException, ReflectionException { 
        return;         
    } 

    public AttributeList setAttributes(AttributeList arg0) {         
        return null; 
    }    
}