| Java Platform, Standard Edition Java Management Extensionsガイド リリース9 E91921-01 |
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/*
* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle or the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Simple definition of a dynamic MBean, named "SimpleDynamic".
*
* The "SimpleDynamic" dynamic MBean shows how to expose for management
* attributes and operations, at runtime, by implementing the
* "javax.management.DynamicMBean" interface.
*
* This MBean exposes for management two attributes and one operation:
* - the read/write "State" attribute,
* - the read only "NbChanges" attribute,
* - the "reset()" operation.
* It does so by putting this information in an MBeanInfo object that
* is returned by the getMBeanInfo() method of the DynamicMBean interface.
*
* It implements the access to its attributes through the getAttribute(),
* getAttributes(), setAttribute(), and setAttributes() methods of the
* DynamicMBean interface.
*
* It implements the invocation of its reset() operation through the
* invoke() method of the DynamicMBean interface.
*
* Note that as "SimpleDynamic" explicitly defines one constructor,
* this constructor must be public and exposed for management through
* the MBeanInfo object.
*/
import java.lang.reflect.Constructor;
import java.util.Iterator;
import javax.management.*;
public class SimpleDynamic
extends NotificationBroadcasterSupport
implements DynamicMBean {
/*
* -----------------------------------------------------
* CONSTRUCTORS
* -----------------------------------------------------
*/
public SimpleDynamic() {
// Build the management information to be exposed by the dynamic MBean
//
buildDynamicMBeanInfo();
}
/*
* -----------------------------------------------------
* IMPLEMENTATION OF THE DynamicMBean INTERFACE
* -----------------------------------------------------
*/
/**
* Allows the value of the specified attribute of the Dynamic MBean to be
* obtained.
*/
public Object getAttribute(String attribute_name)
throws AttributeNotFoundException,
MBeanException,
ReflectionException {
// Check attribute_name is not null to avoid NullPointerException
// later on
//
if (attribute_name == 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 attribute_name and call the corresponding
// getter
//
if (attribute_name.equals("State")) {
return getState();
}
if (attribute_name.equals("NbChanges")) {
return getNbChanges();
}
// If attribute_name has not been recognized throw an
// AttributeNotFoundException
//
throw new AttributeNotFoundException("Cannot find " +
attribute_name +
" attribute in " +
dClassName);
}
/**
* Sets the value of the specified attribute of the Dynamic MBean.
*/
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");
}
// Check for a recognized attribute name and call the corresponding
// setter
//
if (name.equals("State")) {
// if null value, try and see if the setter returns any exception
if (value == null) {
try {
setState( null );
} catch (Exception e) {
throw new InvalidAttributeValueException(
"Cannot set attribute " + name + " to null");
}
}
// if non null value, make sure it is assignable to the attribute
else {
try {
if (Class.forName("java.lang.String").isAssignableFrom(
value.getClass())) {
setState((String) value);
} else {
throw new InvalidAttributeValueException(
"Cannot set attribute " + name + " to a " +
value.getClass().getName() +
" object, String expected");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
// recognize an attempt to set "NbChanges" attribute (read-only):
else if (name.equals("NbChanges")) {
throw new AttributeNotFoundException(
"Cannot set attribute " + name + " because it is read-only");
}
// unrecognized attribute name:
else {
throw new AttributeNotFoundException("Attribute " + name +
" not found in " +
this.getClass().getName());
}
}
/**
* Enables the to get the values of several attributes of the Dynamic MBean.
*/
public AttributeList getAttributes(String[] attributeNames) {
// Check attributeNames is not null to avoid NullPointerException
// later on
//
if (attributeNames == null) {
throw new RuntimeOperationsException(
new IllegalArgumentException("attributeNames[] cannot be null"),
"Cannot invoke a getter of " + dClassName);
}
AttributeList resultList = new AttributeList();
// If attributeNames is empty, return an empty result list
//
if (attributeNames.length == 0)
return resultList;
// Build the result attribute list
//
for (int i = 0 ; i < attributeNames.length ; i++) {
try {
Object value = getAttribute((String) attributeNames[i]);
resultList.add(new Attribute(attributeNames[i],value));
} catch (Exception e) {
e.printStackTrace();
}
}
return resultList;
}
/**
* Sets the values of several attributes of the Dynamic MBean, and returns
* the list of attributes that have been set.
*/
public AttributeList setAttributes(AttributeList attributes) {
// Check attributes is not null to avoid NullPointerException later on
//
if (attributes == null) {
throw new RuntimeOperationsException(
new IllegalArgumentException(
"AttributeList attributes cannot be null"),
"Cannot invoke a setter of " + dClassName);
}
AttributeList resultList = new AttributeList();
// If attributeNames is empty, nothing more to do
//
if (attributes.isEmpty())
return resultList;
// For each attribute, try to set it and add to the result list if
// successfull
//
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(Exception e) {
e.printStackTrace();
}
}
return resultList;
}
/**
* Allows an operation to be invoked on the Dynamic MBean.
*/
public Object invoke(String operationName,
Object params[],
String signature[])
throws MBeanException, ReflectionException {
// Check operationName is not null to avoid NullPointerException
// later on
//
if (operationName == null) {
throw new RuntimeOperationsException(
new IllegalArgumentException("Operation name cannot be null"),
"Cannot invoke a null operation in " + dClassName);
}
// Check for a recognized operation name and call the corresponding
// operation
//
if (operationName.equals("reset")) {
reset();
return null;
} else {
// Unrecognized operation name
//
throw new ReflectionException(
new NoSuchMethodException(operationName),
"Cannot find the operation " + operationName +
" in " + dClassName);
}
}
/**
* This method provides the exposed attributes and operations of the
* Dynamic MBean. It provides this information using an MBeanInfo object.
*/
public MBeanInfo getMBeanInfo() {
// Return the information we want to expose for management:
// the dMBeanInfo private field has been built at instanciation time
//
return dMBeanInfo;
}
/*
* -----------------------------------------------------
* OTHER PUBLIC METHODS
* -----------------------------------------------------
*/
/**
* Getter: get the "State" attribute of the "SimpleDynamic" dynamic MBean.
*/
public String getState() {
return state;
}
/**
* Setter: set the "State" attribute of the "SimpleDynamic" dynamic MBean.
*/
public void setState(String s) {
state = s;
nbChanges++;
}
/**
* Getter: get the "NbChanges" attribute of the "SimpleDynamic" dynamic
* MBean.
*/
public Integer getNbChanges() {
return new Integer(nbChanges);
}
/**
* Operation: reset to their initial values the "State" and "NbChanges"
* attributes of the "SimpleDynamic" dynamic MBean.
*/
public void reset() {
AttributeChangeNotification acn =
new AttributeChangeNotification(this,
0,
0,
"NbChanges reset",
"NbChanges",
"Integer",
new Integer(nbChanges),
new Integer(0));
state = "initial state";
nbChanges = 0;
nbResets++;
sendNotification(acn);
}
/**
* Return the "NbResets" property.
* This method is not a Getter in the JMX sense because
* it is not returned by the getMBeanInfo() method.
*/
public Integer getNbResets() {
return new Integer(nbResets);
}
/*
* -----------------------------------------------------
* PRIVATE METHODS
* -----------------------------------------------------
*/
/**
* Build the private dMBeanInfo field,
* which represents the management interface exposed by the MBean,
* that is, the set of attributes, constructors, operations and
* notifications which are available for management.
*
* A reference to the dMBeanInfo object is returned by the getMBeanInfo()
* method of the DynamicMBean interface. Note that, once constructed, an
* MBeanInfo object is immutable.
*/
private void buildDynamicMBeanInfo() {
dAttributes[0] =
new MBeanAttributeInfo("State",
"java.lang.String",
"State string.",
true,
true,
false);
dAttributes[1] =
new MBeanAttributeInfo("NbChanges",
"java.lang.Integer",
"Number of times the " +
"State string has been changed.",
true,
false,
false);
Constructor[] constructors = this.getClass().getConstructors();
dConstructors[0] =
new MBeanConstructorInfo("Constructs a " +
"SimpleDynamic object",
constructors[0]);
MBeanParameterInfo[] params = null;
dOperations[0] =
new MBeanOperationInfo("reset",
"reset State and NbChanges " +
"attributes to their initial values",
params ,
"void",
MBeanOperationInfo.ACTION);
dNotifications[0] =
new MBeanNotificationInfo(
new String[] { AttributeChangeNotification.ATTRIBUTE_CHANGE },
AttributeChangeNotification.class.getName(),
"This notification is emitted when the reset() method is called.");
dMBeanInfo = new MBeanInfo(dClassName,
dDescription,
dAttributes,
dConstructors,
dOperations,
dNotifications);
}
/*
* -----------------------------------------------------
* PRIVATE VARIABLES
* -----------------------------------------------------
*/
private String state = "initial state";
private int nbChanges = 0;
private int nbResets = 0;
private String dClassName = this.getClass().getName();
private String dDescription = "Simple implementation of a dynamic MBean.";
private MBeanAttributeInfo[] dAttributes =
new MBeanAttributeInfo[2];
private MBeanConstructorInfo[] dConstructors =
new MBeanConstructorInfo[1];
private MBeanNotificationInfo[] dNotifications =
new MBeanNotificationInfo[1];
private MBeanOperationInfo[] dOperations =
new MBeanOperationInfo[1];
private MBeanInfo dMBeanInfo = null;
}
