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歡迎支持筆者新作：《深入理解Kafka:核心設(shè)計(jì)與實(shí)踐原理》和《RabbitMQ實(shí)戰(zhàn)指南》，同時(shí)歡迎關(guān)注筆者的微信公眾號(hào)：朱小廝的博客。

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歡迎跳轉(zhuǎn)到本文的原文鏈接：https://honeypps.com/java/jmx-quick-start-4-dynamic-mbean/

Apache Commons Modeler

前面的Model MBean的創(chuàng)建方式看上去特別復(fù)雜，一個(gè)簡(jiǎn)單功能的類ModelMBeanUtils 寫了很多代碼，那有木有簡(jiǎn)單點(diǎn)的方式呢，答案是肯定的，這里就引出了Apache Commons Modeler（使用這個(gè)需要在classpath中導(dǎo)入commons-modeler-2.0.1.jar以及modeler的依賴項(xiàng)目commons-logging-1.1.3.jar，下載地址：http://commons.apache.org/proper/commons-modeler/download_modeler.cgi），使用Apache的Moleler庫(kù)創(chuàng)建Model MBean最大幫助是，我們不需要再寫復(fù)雜的代碼來(lái)創(chuàng)建ModelMBeanInfo對(duì)象了。只需要一個(gè)MBean描述符（實(shí)際上就是一個(gè)xml配置文件，Apache Commons Modeler將ModelMBeanUtils 復(fù)雜的創(chuàng)建過(guò)程轉(zhuǎn)移到xml中來(lái)配置，然后自身模塊創(chuàng)建對(duì)象代替ModelMBeanUtils 的功能，簡(jiǎn)化用戶的操作）來(lái)對(duì)Model MBean進(jìn)行描述，就可以輕松的創(chuàng)建Model MBean.

下面來(lái)講前面的Hello.java和HelloAgent.java的例子采用Apache Commons Modele進(jìn)行改造。

首先還是Hello.java，和Model MBean中的一樣，沒(méi)有implements任何接口。

package com.test.jmx.modeler;public class Hello{private String name;public String getName() {return name;}public void setName(String name) {this.name= name;}public void printHello() {System.out.println("Hello World, "+name);}public void printHello(String whoName) {System.out.println("Hello, "+whoName);} }

接下去就是最關(guān)鍵的描述文件(mbeans-descriptors.xml)了：

<?xml version="1.0" encoding="UTF-8" ?> <mbeans-descriptors><mbean name="Hello" description="the hello bean" domain="MyMBean" group="helloGroup" type="com.test.jmx.modeler.Hello"><attribute name="name" description="a name attribute" type="java.lang.String" writeable="true"/><operation name="printHello" description="public void printHello()" impact="ACTION" returnType="void"/><operation name="printHello" description="public void printHello(String whoName)" impact="ACTION" returnType="void"><parameter name="whoName" description="method parameter of printHello" type="java.lang.String"></parameter> </operation></mbean> </mbeans-descriptors>

描述文件的名字可以隨意，最主要的是要和下面的HelloAgent.java對(duì)應(yīng)起來(lái)。
通過(guò)這個(gè)xml文件的定義就描述了Model MBean所需要的metadata信息和一個(gè)基本的ModelMBean實(shí)現(xiàn)。
關(guān)于這個(gè)xml文件有幾個(gè)需要說(shuō)明的地方：

<mbean>的屬性classname,name,type:

• name屬性是每個(gè)MBean被Registry對(duì)象注冊(cè)的對(duì)象名
• type屬性是真正被管理資源的全面（包括包名）
• classname屬性是用戶擴(kuò)展的用于實(shí)現(xiàn)代理功能的Model MBean的全名，如果不提供Modeler會(huì)使用BaseModelMBean；如果提供了代理的ModelMBean對(duì)象，在使用時(shí)可以使用如下的代碼樣本訪問(wèn)他所代理的資源對(duì)象。

其余的標(biāo)簽就比較好理解了。綜述：上面所示代碼聲明了一個(gè)Model MBean, 唯一標(biāo)示是“Hello”,該MBean負(fù)責(zé)管理的對(duì)象是com.test.jmx.modeler.Hello的實(shí)例。域是MyMBean。這個(gè)MBean暴露了一個(gè)屬性name和兩個(gè)方法printHello()和printHello(String whoName).

下面是新的HelloAgent.java的代碼：

package com.test.jmx.modeler;import com.sun.jdmk.comm.HtmlAdaptorServer; import org.apache.commons.modeler.ManagedBean; import org.apache.commons.modeler.Registry;import javax.management.MBeanServer; import javax.management.ObjectName; import javax.management.modelmbean.ModelMBean; import java.io.InputStream;public class HelloAgent {public static void main(String[] args) throws Exception { // 需要將xml信息讀入到Registry對(duì)象中Registry registry = Registry.getRegistry(null,null);InputStream stream = HelloAgent.class.getResourceAsStream("mbeans-descriptors.xml");registry.loadMetadata(stream);MBeanServer server = registry.getMBeanServer();// 之前是：MBeanServer server = ManagementFactory.getPlatformMBeanServer();ManagedBean managed = registry.findManagedBean("Hello");ObjectName helloName = new ObjectName(managed.getDomain()+":name=HelloWorld"); // 以前是Hello hello = new Hello(); 為什么要多個(gè)createMBean？因?yàn)楝F(xiàn)在的寫法沒(méi)有寫MBean,所以才要?jiǎng)討B(tài)生成一個(gè)，以前就直接 // 把new hello()注冊(cè)到MBeanServer就可以了，server會(huì)自動(dòng)找到它的HelloMBean接口文件。ModelMBean hello = managed.createMBean(new Hello());server.registerMBean(hello,helloName);ObjectName adapterName = new ObjectName(managed.getDomain()+":name = htmladapter,port=8082");HtmlAdaptorServer adapter = new HtmlAdaptorServer();server.registerMBean(adapter,adapterName);adapter.start();} }

注意這里的Registry是指org.apache.commons.modeler.Registry，因?yàn)镴MX自身也有一個(gè)Registry(java.rmi.registry.Registry)。通過(guò)Modeler組件提供的Registry對(duì)象，可以很方便的完成MBeanServer的創(chuàng)建。
運(yùn)行效果和之前的一樣，這里就不贅述了，有興趣的小伙伴可以試一下。

Dynamic MBean

四種類型的MBean，前面所講的都是常用的，現(xiàn)在還剩兩種Open MBean就不講述了，這里簡(jiǎn)單記錄下Dynamic MBean。
Dynamic MBean不需要自定義MBean接口，只需要實(shí)現(xiàn)DynamicMBean接口即可，Dynamic MBean沒(méi)有任何明顯些在代碼里的屬性和方法，所有的屬性和方法都是通過(guò)反射結(jié)合JMX提供的輔助元數(shù)據(jù)從而動(dòng)態(tài)生成。
下面的代碼中首先定義了一個(gè)屬性name和一個(gè)方法print,之后在管理界面（localhost:8082）中點(diǎn)擊print之后生成一個(gè)print1的方法。
Dynamic MBean的代碼如下：

package com.test.jmx.DynamicMBean;import javax.management.*; import java.lang.reflect.Constructor; import java.util.Iterator;/*** Created by hidden on 2016/10/9.*/ public class HelloDynamic implements DynamicMBean {private String name;private MBeanInfo mBeanInfo = null;private String className;private String description;private MBeanAttributeInfo[] attributes;private MBeanConstructorInfo[] constructors;private MBeanOperationInfo[] operations;MBeanNotificationInfo[] mBeanNotificationInfoArray;private void init(){className = this.getClass().getName();description = "Simple implementation of a dynamic MBean.";attributes = new MBeanAttributeInfo[1];constructors = new MBeanConstructorInfo[1];operations = new MBeanOperationInfo[1];mBeanNotificationInfoArray = new MBeanNotificationInfo[0];}private void buildDynamicMBean(){Constructor[] thisConstructors = this.getClass().getConstructors();constructors[0] = new MBeanConstructorInfo("HelloDynamic(): Constructs a HelloDynamic Object",thisConstructors[0]);attributes[0] = new MBeanAttributeInfo("name","java.lang.String","Name:name string.",true,true,false);MBeanParameterInfo[] params = null;operations[0] = new MBeanOperationInfo("print","print():print the name",params,"void",MBeanOperationInfo.INFO);mBeanInfo = new MBeanInfo(className,description,attributes,constructors,operations,mBeanNotificationInfoArray);}public HelloDynamic(){init();buildDynamicMBean();}private void dynamicAddOperation(){init();operations = new MBeanOperationInfo[2];buildDynamicMBean();operations[1] = new MBeanOperationInfo("print1","print1():print the name",null,"void",MBeanOperationInfo.INFO);mBeanInfo = new MBeanInfo(className,description,attributes,constructors,operations,mBeanNotificationInfoArray);}@Overridepublic Object getAttribute(String attribute) throws AttributeNotFoundException, MBeanException, ReflectionException {if (attribute == null) {return null;}if (attribute.equals("Name")) {return name;}return null;}@Overridepublic void setAttribute(Attribute attribute) throws AttributeNotFoundException, InvalidAttributeValueException, MBeanException, ReflectionException {if (attribute == null) {return;}String Name = attribute.getName();Object value = attribute.getValue();try {if (Name.equals("Name")) {if (value == null) {name=null;} else if (Class.forName("java.lang.String").isAssignableFrom(value.getClass())) {name = (String) name;}}} catch (ClassNotFoundException e) {e.printStackTrace();}}@Overridepublic AttributeList getAttributes(String[] attributes) {if (attributes == null) {return null;}AttributeList resultList = new AttributeList(); // if (attributes.length == 0) { // return resultList; // }for(int i=0;i<attributes.length;i++){try {Object value = getAttribute(attributes[i]);resultList.add(new Attribute(attributes[i],value));} catch (AttributeNotFoundException e) {e.printStackTrace();} catch (MBeanException e) {e.printStackTrace();} catch (ReflectionException e) {e.printStackTrace();}}return resultList;}@Overridepublic AttributeList setAttributes(AttributeList attributes) {if (attributes == null) {return null;}AttributeList resultList = new AttributeList();if(attributes.isEmpty()){return resultList;}for(Iterator i = attributes.iterator();i.hasNext();){Attribute attr = (Attribute) i.next();try {setAttribute(attr);String name = attr.getName();Object value = getAttribute(name);resultList.add(new Attribute(name,value));} catch (AttributeNotFoundException e) {e.printStackTrace();} catch (InvalidAttributeValueException e) {e.printStackTrace();} catch (MBeanException e) {e.printStackTrace();} catch (ReflectionException e) {e.printStackTrace();}}return resultList;}@Overridepublic Object invoke(String actionName, Object[] params, String[] signature) throws MBeanException, ReflectionException {if(actionName.equals("print")){System.out.println("Hello, "+name+",this is HelloDynamic!");dynamicAddOperation();return null;}else if(actionName.equals("print1")){System.out.println("這是動(dòng)態(tài)增加的一個(gè)方法print1");return null;}else {throw new ReflectionException(new NoSuchMethodException(actionName),"Cannot find the operation "+actionName+" in "+className);}}@Overridepublic MBeanInfo getMBeanInfo() {return mBeanInfo;} }

通過(guò)Agent調(diào)用Dynamic MBean：

package com.test.jmx.DynamicMBean;import com.sun.jdmk.comm.HtmlAdaptorServer;import javax.management.*; import java.lang.management.ManagementFactory; import java.util.concurrent.TimeUnit;public class HelloAgent {public static void main(String[] args) throws MalformedObjectNameException, NotCompliantMBeanException, InstanceAlreadyExistsException, MBeanRegistrationException {MBeanServer server = ManagementFactory.getPlatformMBeanServer();ObjectName helloName = new ObjectName("MyMBean:name=helloDynamic");HelloDynamic hello = new HelloDynamic();server.registerMBean(hello,helloName);ObjectName adapterName = new ObjectName("MyMBean:name=htmladapter");HtmlAdaptorServer adapter = new HtmlAdaptorServer();server.registerMBean(adapter,adapterName);adapter.start();} }

運(yùn)行效果圖如下：

運(yùn)行結(jié)果：

Hello, null,this is HelloDynamic! 這是動(dòng)態(tài)增加的一個(gè)方法print1

wanna more?

從零開始玩轉(zhuǎn)JMX(一)——簡(jiǎn)介和Standard MBean

從零開始玩轉(zhuǎn)JMX(二)——Condition

從零開始玩轉(zhuǎn)JMX(三)——Model MBean

從零開始玩轉(zhuǎn)JMX(四)——Apache Commons Modeler & Dynamic MBean

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參考資料

JMX整理

JMX簡(jiǎn)介

http://blog.csdn.net/DryKillLogic/article/category/762777

用Apache的commons-modeler來(lái)輔助開發(fā)JMX

歡迎跳轉(zhuǎn)到本文的原文鏈接：https://honeypps.com/java/jmx-quick-start-4-dynamic-mbean/

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歡迎支持筆者新作：《深入理解Kafka:核心設(shè)計(jì)與實(shí)踐原理》和《RabbitMQ實(shí)戰(zhàn)指南》，同時(shí)歡迎關(guān)注筆者的微信公眾號(hào)：朱小廝的博客。

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