alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

What this is

This file is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Other links

The source code


package org.apache.log4j.jmx;

import java.lang.reflect.Constructor;
import org.apache.log4j.Logger;
import org.apache.log4j.Level;
import org.apache.log4j.Appender;
import org.apache.log4j.helpers.OptionConverter;

import java.util.Vector;
import java.util.Enumeration;

import javax.management.MBeanAttributeInfo;
import javax.management.MBeanConstructorInfo;
import javax.management.MBeanNotificationInfo;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanParameterInfo;
import javax.management.ObjectName;
import javax.management.MBeanInfo;
import javax.management.Attribute;

import javax.management.MBeanException;
import javax.management.AttributeNotFoundException;
import javax.management.RuntimeOperationsException;
import javax.management.ReflectionException;
import javax.management.InvalidAttributeValueException;
import javax.management.NotificationListener;
import javax.management.Notification;

public class LoggerDynamicMBean extends AbstractDynamicMBean
                                  implements NotificationListener {

  private MBeanConstructorInfo[] dConstructors = new MBeanConstructorInfo[1];
  private MBeanOperationInfo[] dOperations = new MBeanOperationInfo[1];

  private Vector dAttributes = new Vector();
  private String dClassName = this.getClass().getName();

  private String dDescription =
     "This MBean acts as a management facade for a org.apache.log4j.Logger instance.";

  // This Logger instance is for logging.
  private static Logger cat = Logger.getLogger(LoggerDynamicMBean.class);

  // We wrap this Logger instance.
  private Logger logger;

  public LoggerDynamicMBean(Logger logger) {
    this.logger = logger;
    buildDynamicMBeanInfo();
  }

  public
  void handleNotification(Notification notification, Object handback) {
    cat.debug("Received notification: "+notification.getType());
    registerAppenderMBean((Appender) notification.getUserData() );


  }

  private
  void buildDynamicMBeanInfo() {
    Constructor[] constructors = this.getClass().getConstructors();
    dConstructors[0] = new MBeanConstructorInfo(
             "HierarchyDynamicMBean(): Constructs a HierarchyDynamicMBean instance",
	     constructors[0]);

    dAttributes.add(new MBeanAttributeInfo("name",
					   "java.lang.String",
					   "The name of this Logger.",
					   true,
					   false,
					   false));

    dAttributes.add(new MBeanAttributeInfo("priority",
					   "java.lang.String",
					   "The priority of this logger.",
					   true,
					   true,
					   false));





    MBeanParameterInfo[] params = new MBeanParameterInfo[2];
    params[0] = new MBeanParameterInfo("class name", "java.lang.String",
				       "add an appender to this logger");
    params[1] = new MBeanParameterInfo("appender name", "java.lang.String",
				       "name of the appender");

    dOperations[0] = new MBeanOperationInfo("addAppender",
					    "addAppender(): add an appender",
					    params,
					    "void",
					    MBeanOperationInfo.ACTION);
  }

  protected
  Logger getLogger() {
    return logger;
  }


  public
  MBeanInfo getMBeanInfo() {
    //cat.debug("getMBeanInfo called.");

    MBeanAttributeInfo[] attribs = new MBeanAttributeInfo[dAttributes.size()];
    dAttributes.toArray(attribs);

    MBeanInfo mb = new MBeanInfo(dClassName,
			 dDescription,
			 attribs,
			 dConstructors,
			 dOperations,
			 new MBeanNotificationInfo[0]);
    //cat.debug("getMBeanInfo exit.");
    return mb;
  }

  public
  Object invoke(String operationName, Object params[], String signature[])
    throws MBeanException,
    ReflectionException {

    if(operationName.equals("addAppender")) {
      addAppender((String) params[0], (String) params[1]);
      return "Hello world.";
    }

    return null;
  }


  public
  Object getAttribute(String attributeName) throws AttributeNotFoundException,
                                                   MBeanException,
                                                   ReflectionException {

       // Check attributeName is not null to avoid NullPointerException later on
    if (attributeName == null) {
      throw new RuntimeOperationsException(new IllegalArgumentException(
			"Attribute name cannot be null"),
       "Cannot invoke a getter of " + dClassName + " with null attribute name");
    }

    // Check for a recognized attributeName and call the corresponding getter
    if (attributeName.equals("name")) {
      return logger.getName();
    }  else if(attributeName.equals("priority")) {
      Level l = logger.getLevel();
      if(l == null) {
	return null;
      } else {
	return l.toString();
      }
    } else if(attributeName.startsWith("appender=")) {
      try {
	return new ObjectName("log4j:"+attributeName );
      } catch(Exception e) {
	cat.error("Could not create ObjectName" + attributeName);
      }
    }


    // If attributeName has not been recognized throw an AttributeNotFoundException
    throw(new AttributeNotFoundException("Cannot find " + attributeName +
					 " attribute in " + dClassName));

  }


  void addAppender(String appenderClass, String appenderName) {
    cat.debug("addAppender called with "+appenderClass+", "+appenderName);
    Appender appender = (Appender)
       OptionConverter.instantiateByClassName(appenderClass,
					      org.apache.log4j.Appender.class,
					      null);
    appender.setName(appenderName);
    logger.addAppender(appender);

    //appenderMBeanRegistration();

  }


  public
  void setAttribute(Attribute attribute) throws AttributeNotFoundException,
                                                InvalidAttributeValueException,
                                                MBeanException,
                                                ReflectionException {

    // Check attribute is not null to avoid NullPointerException later on
    if (attribute == null) {
      throw new RuntimeOperationsException(
                  new IllegalArgumentException("Attribute cannot be null"),
		  "Cannot invoke a setter of " + dClassName +
		  " with null attribute");
    }
    String name = attribute.getName();
    Object value = attribute.getValue();

    if (name == null) {
      throw new RuntimeOperationsException(
                    new IllegalArgumentException("Attribute name cannot be null"),
		    "Cannot invoke the setter of "+dClassName+
		    " with null attribute name");
    }


    if(name.equals("priority")) {
      if (value instanceof String) {
	String s = (String) value;
	Level p = logger.getLevel();
	if(s.equalsIgnoreCase("NULL")) {
	  p = null;
	} else {
	  p = OptionConverter.toLevel(s, p);
	}
	logger.setPriority(p);
      }
    } else {
      throw(new AttributeNotFoundException("Attribute " + name +
					   " not found in " +
					   this.getClass().getName()));
    }
  }

  void appenderMBeanRegistration() {
    Enumeration enum = logger.getAllAppenders();
    while(enum.hasMoreElements()) {
      Appender appender = (Appender) enum.nextElement();
      registerAppenderMBean(appender);
    }
  }

  void registerAppenderMBean(Appender appender) {
    String name = appender.getName();
    cat.debug("Adding AppenderMBean for appender named "+name);
    ObjectName objectName = null;
    try {
      AppenderDynamicMBean appenderMBean = new AppenderDynamicMBean(appender);
      objectName = new ObjectName("log4j", "appender", name);
      server.registerMBean(appenderMBean, objectName);

      dAttributes.add(new MBeanAttributeInfo("appender="+name,
					     "javax.management.ObjectName",
					     "The "+name+" appender.",
					     true,
					     true,
					     false));

    } catch(Exception e) {
      cat.error("Could not add appenderMBean for ["+name+"].", e);
    }
  }

  public
  void postRegister(java.lang.Boolean registrationDone) {
    appenderMBeanRegistration();
  }
}
... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.