JMX和Spring –第2部分

嗨，在我的前一篇文章中，我解释了如何通过Spring设置JMX服务器以及如何通过身份验证和授权保护对它的访问。

在本文中，我将展示如何实现一个简单的MBean，该MBean允许用户在运行时更改Log4j记录器的级别，而无需重新启动应用程序。

为了方便测试，Spring配置与我的前一篇文章仅作了些许更改。 实质保持不变。

Spring配置

 <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd">


    <bean id="propertyConfigurer"
       class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:jemos-jmx.properties</value>
                <value>file:///${user.home}/.secure/jmxconnector-credentials.properties</value>
            </list>
        </property>
    </bean>

<!-- In order to automatically detect MBeans we need to recognise Spring beans -->
    <context:component-scan base-package="uk.co.jemos.experiments.jmx.mbeans" />

<!-- This causes MBeans annotations to be recognised and MBeans to be registered with the JMX server -->
    <context:mbean-export default-domain="jemos.mbeans"/>

    <bean id="jemosJmxServer" class="org.springframework.jmx.support.ConnectorServerFactoryBean"
        depends-on="rmiRegistry">
        <property name="objectName" value="connector:name=rmi" />
        <property name="serviceUrl"
            value="service:jmx:rmi://localhost/jndi/rmi://localhost:${jemos.jmx.rmi.port}/jemosJmxConnector" />
        <property name="environment">
            <!-- the following is only valid when the sun jmx implementation is used -->
            <map>
                <entry key="jmx.remote.x.password.file" value="${user.home}/.secure/jmxremote.password" />
                <entry key="jmx.remote.x.access.file" value="${user.home}/.secure/jmxremote.access" />
            </map>
        </property>
    </bean>

    <bean id="rmiRegistry" class="org.springframework.remoting.rmi.RmiRegistryFactoryBean">
        <property name="port" value="${jemos.jmx.rmi.port}" />
    </bean>

<!-- Used for testing -->
    <bean id="clientConnector" class="org.springframework.jmx.support.MBeanServerConnectionFactoryBean"
        depends-on="jemosJmxServer">
          <property name="serviceUrl" value="service:jmx:rmi://localhost/jndi/rmi://localhost:${jemos.jmx.rmi.port}/jemosJmxConnector"/>
          <property name="environment">
            <map>
                <entry key="jmx.remote.credentials">
                  <bean factory-method="commaDelimitedListToStringArray">
                    <constructor-arg value="${jmx.username},${jmx.password}" />
                  </bean>
                </entry>
          </map>
        </property>
    </bean>

    
</beans>

我们唯一感兴趣的配置部分是扫描Spring组件和MBean导出器的声明（这也导致MBean注释被识别，Spring Bean作为MBeans向JMX服务器注册）

LoggerConfigurator MBean

package uk.co.jemos.experiments.jmx.mbeans;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.springframework.jmx.export.annotation.ManagedOperation;
import org.springframework.jmx.export.annotation.ManagedOperationParameter;
import org.springframework.jmx.export.annotation.ManagedOperationParameters;
import org.springframework.jmx.export.annotation.ManagedResource;
import org.springframework.stereotype.Component;

/**
 * MBean which allows clients to change or retrieve the logging level for a
 * Log4j Logger at runtime.
 * 
 * @author mtedone
 * 
 */
@Component
@ManagedResource(objectName = LoggerConfigurator.MBEAN_NAME, //
description = "Allows clients to set the Log4j Logger level at runtime")
public class LoggerConfigurator {
    
    public static final String MBEAN_NAME = "jemos.mbeans:type=config,name=LoggingConfiguration";

    @ManagedOperation(description = "Returns the Logger LEVEL for the given logger name")
    @ManagedOperationParameters({ @ManagedOperationParameter(description = "The Logger Name", name = "loggerName"), })
    public String getLoggerLevel(String loggerName) {

        Logger logger = Logger.getLogger(loggerName);
        Level loggerLevel = logger.getLevel();

        return loggerLevel == null ? "The logger " + loggerName
                + " has not level" : loggerLevel.toString();

    }

    @ManagedOperation(description = "Set Logger Level")
    @ManagedOperationParameters({
            @ManagedOperationParameter(description = "The Logger Name", name = "loggerName"),
            @ManagedOperationParameter(description = "The Level to which the Logger must be set", name = "loggerLevel") })
    public void setLoggerLevel(String loggerName, String loggerLevel) {

        Logger thisLogger = Logger.getLogger(this.getClass());
        thisLogger.setLevel(Level.INFO);

        Logger logger = Logger.getLogger(loggerName);

        logger.setLevel(Level.toLevel(loggerLevel, Level.INFO));

        thisLogger.info("Set logger " + loggerName + " to level "
                + logger.getLevel());

    }

}

除了Spring JMX注释（以粗体显示）之外，这是一个普通的Spring bean。 但是，使用这些注释，我们制作了一个MBean，并且该bean将在启动时向JMX服务器注册。

@ManagedOperation和@ManagedOperationParameters批注确定在jconsole上显示的内容。 可以省略这些注释，但是在不提供任何有关参数类型的信息的情况下，参数名称将不会变成p1和p2之类的东西。

例如，使用值foo.bar.baz和INFO调用该函数将导致以下输出：

...snip

2011-08-11 21:33:36 LoggerConfigurator [INFO] Set logger foo.bar.baz to level INFO

在本系列的下一篇和最后一篇文章中，我将展示如何设置MBean，以在达到HEAP内存阈值时向侦听器发出警报，如我以前的一篇文章中所述

继续第3部分 。

参考： JMX和Spring –我们的JCG合作伙伴 Marco Tedone的第2部分 ，位于Marco Tedone的博客博客中。