JMX : Standard MBean

Standard MBean由一个接口和一个实现类组成。

命名规范 :

接口 : XXXMBean

实现类 : XXX

按照约定，MBean的name为XXX。自定。

接口中的每个方法定义了一个attribute或operation。

以get或set开头的方法 : 如果符合getter或setter的模式，就是定义了一个attribute，类型为getter的返回值类型或setter参数类型。

其他方法 : 定义了一个operation。

示例:

package test.xue.mbean;

public interface HelloMBean {
	public void sayHello();
	public int add(int x, int y);
	
	public String getName();
	
	public int getCacheSize();
	public void setCacheSize(int size);
	
	public void setText();
	public void settitle(String title);
}

HelloMBean接口定义了3个attribute和3个operation :

attributes:

name : readonly

cacheSize : readable and writable

title : writable

operations:

sayHello

add

setText : 不符合setter模式。

实现类:

package test.xue.mbean;

public class Hello implements HelloMBean {
	
	private final String name = "My HelloMBean";
	private int cacheSize = 1024;
	private String title;

	@Override
	public void sayHello() {
		System.out.println("hello, my HelloMBean");
	}

	@Override
	public int add(int x, int y) {
		return x+y;
	}

	@Override
	public String getName() {
		return name;
	}

	@Override
	public int getCacheSize() {
		return cacheSize;
	}

	@Override
	public void setCacheSize(int size) {
		this.cacheSize = size;
		System.out.println("cacheSize changed : " + size);
	}

	@Override
	public void setText() {
		System.out.println("setText called");
	}
	
	@Override
	public void settitle(String title) {
		this.title = title;
		System.out.println("title changed : " + title);
	}
}

以上，HelloMBean和Hello就定义了一个MBean，通过这个MBean的operation和attribute，就可以管理特定的资源。

现在，就可以创建一个JMX agent来通过MBean管理资源了。

package test.xue.mbean.management;

import java.lang.management.ManagementFactory;

import javax.management.InstanceAlreadyExistsException;
import javax.management.MBeanRegistrationException;
import javax.management.MBeanServer;
import javax.management.MalformedObjectNameException;
import javax.management.NotCompliantMBeanException;
import javax.management.ObjectName;

import test.xue.mbean.Hello;

public class HelloAgent {
	public static void main(String[] args) throws MalformedObjectNameException,
			NullPointerException, InstanceAlreadyExistsException,
			MBeanRegistrationException, NotCompliantMBeanException,
			InterruptedException {
		MBeanServer server = ManagementFactory.getPlatformMBeanServer();
		ObjectName name = new ObjectName("test.xue.mbean:type=Hello"); // any name
//		ObjectName name = new ObjectName("test.xue.mbean22:type=Hello2"); // also works

		Hello mbean = new Hello();
		server.registerMBean(mbean, name);

		System.out.println("waiting here for remote management...");
		Thread.sleep(Long.MAX_VALUE);
	}
}

如上，每个MBean都需要一个ObjectName，ObjectName的命名规范:

domain:(key=value)+

例子中的domain=test.xue.mbean，type=Hello，可任意指定。

可通过JConsole来测试此JMX agent

运行 : jconsole

连接以后，

可以尝试修改attributes，调用operations，同时注意控制台输出。

如果出现javax.management.NotCompliantMBeanException :

Exception in thread "main" javax.management.NotCompliantMBeanException: MBean class test.xue.mbean.Hello2 does not implement DynamicMBean, neither follows the Standard MBean conventions (javax.management.NotCompliantMBeanException: Class test.xue.mbean.Hello2 is not a JMX compliant Standard MBean) nor the MXBean conventions (javax.management.NotCompliantMBeanException: test.xue.mbean.Hello2: Class test.xue.mbean.Hello2 is not a JMX compliant MXBean)
	at com.sun.jmx.mbeanserver.Introspector.checkCompliance(Unknown Source)
	at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(Unknown Source)
	at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(Unknown Source)
	at test.xue.mbean.management.HelloAgent.main(HelloAgent.java:24)

可能的原因是:

接口和实现类的名字不符合命名规范: XXXMBean, XXX。