mbeanclientinterceptor.java

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	 */
	protected MBeanServer locateMBeanServer(String agentId) throws MBeanServerNotFoundException {
		return JmxUtils.locateMBeanServer(agentId);
	}

	/**
	 * Loads the management interface info for the configured MBean into the caches.
	 * This information is used by the proxy when determining whether an invocation matches
	 * a valid operation or attribute on the management interface of the managed resource.
	 */
	private void retrieveMBeanInfo() throws MBeanServerNotFoundException, MBeanInfoRetrievalException {
		try {
			MBeanInfo info = this.server.getMBeanInfo(this.objectName);

			// get attributes
			MBeanAttributeInfo[] attributeInfo = info.getAttributes();
			this.allowedAttributes = new HashMap(attributeInfo.length);

			for (int x = 0; x < attributeInfo.length; x++) {
				this.allowedAttributes.put(attributeInfo[x].getName(), attributeInfo[x]);
			}

			// get operations
			MBeanOperationInfo[] operationInfo = info.getOperations();
			this.allowedOperations = new HashMap(operationInfo.length);

			for (int x = 0; x < operationInfo.length; x++) {
				MBeanOperationInfo opInfo = operationInfo[x];
				Class[] paramTypes = JmxUtils.parameterInfoToTypes(opInfo.getSignature(), this.beanClassLoader);
				this.allowedOperations.put(new MethodCacheKey(opInfo.getName(), paramTypes), opInfo);
			}
		}
		catch (ClassNotFoundException ex) {
			throw new MBeanInfoRetrievalException("Unable to locate class specified in method signature", ex);
		}
		catch (IntrospectionException ex) {
			throw new MBeanInfoRetrievalException("Unable to obtain MBean info for bean [" + this.objectName + "]", ex);
		}
		catch (InstanceNotFoundException ex) {
			// if we are this far this shouldn't happen, but...
			throw new MBeanInfoRetrievalException("Unable to obtain MBean info for bean [" + this.objectName +
					"]: it is likely that this bean was unregistered during the proxy creation process",
					ex);
		}
		catch (ReflectionException ex) {
			throw new MBeanInfoRetrievalException("Unable to read MBean info for bean [ " + this.objectName + "]", ex);
		}
		catch (IOException ex) {
			throw new MBeanInfoRetrievalException(
					"An IOException occurred when communicating with the MBeanServer. " +
							"It is likely that you are communicating with a remote MBeanServer. " +
							"Check the inner exception for exact details.", ex);
		}
	}


	/**
	 * Route the invocation to the configured managed resource. Correctly routes JavaBean property
	 * access to <code>MBeanServerConnection.get/setAttribute</code> and method invocation to
	 * <code>MBeanServerConnection.invoke</code>. Any attempt to invoke a method that does not
	 * correspond to an attribute or operation defined in the management interface of the managed
	 * resource results in an <code>InvalidInvocationException</code>.
	 * @param invocation the <code>MethodInvocation</code> to re-route.
	 * @return the value returned as a result of the re-routed invocation.
	 * @throws InvocationFailureException if the invocation does not match an attribute or
	 * operation on the management interface of the resource.
	 * @throws Throwable typically as the result of an error during invocation
	 */
	public Object invoke(MethodInvocation invocation) throws Throwable {
		// Lazily connect to MBeanServer?
		if (!this.connectOnStartup) {
			synchronized (this) {
				if (this.server == null) {
					logger.debug("Lazily establishing MBeanServer connection");
					connect();
				}

				if (this.allowedAttributes == null) {
					logger.debug("Lazily initializing MBeanInfo cache");
					retrieveMBeanInfo();
				}
			}
		}

		try {
			PropertyDescriptor pd = BeanUtils.findPropertyForMethod(invocation.getMethod());
			if (pd != null) {
				return invokeAttribute(pd, invocation);
			}
			else {
				return invokeOperation(invocation.getMethod(), invocation.getArguments());
			}
		}
		catch (JMException ex) {
			throw new InvocationFailureException("JMX access failed", ex);
		}
		catch (IOException ex) {
			throw new InvocationFailureException("JMX access failed", ex);
		}
	}

	private Object invokeAttribute(PropertyDescriptor pd, MethodInvocation invocation)
			throws JMException, IOException {

		String attributeName = JmxUtils.getAttributeName(pd, this.useStrictCasing);
		MBeanAttributeInfo inf = (MBeanAttributeInfo) this.allowedAttributes.get(attributeName);

		// If no attribute is returned, we know that it is not defined in the
		// management interface.
		if (inf == null) {
			throw new InvalidInvocationException(
					"Attribute '" + pd.getName() + "' is not exposed on the management interface");
		}
		if (invocation.getMethod().equals(pd.getReadMethod())) {
			if (inf.isReadable()) {
				return this.server.getAttribute(this.objectName, attributeName);
			}
			else {
				throw new InvalidInvocationException("Attribute '" + attributeName + "' is not readable");
			}
		}
		else if (invocation.getMethod().equals(pd.getWriteMethod())) {
			if (inf.isWritable()) {
				this.server.setAttribute(this.objectName, new Attribute(attributeName, invocation.getArguments()[0]));
				return null;
			}
			else {
				throw new InvalidInvocationException("Attribute '" + attributeName + "' is not writable");
			}
		}
		else {
			throw new IllegalStateException(
					"Method [" + invocation.getMethod() + "] is neither a bean property getter nor a setter");
		}
	}

	/**
	 * Routes a method invocation (not a property get/set) to the corresponding
	 * operation on the managed resource.
	 * @param method the method corresponding to operation on the managed resource.
	 * @param args the invocation arguments
	 * @return the value returned by the method invocation.
	 */
	private Object invokeOperation(Method method, Object[] args) throws JMException, IOException {
		MethodCacheKey key = new MethodCacheKey(method.getName(), method.getParameterTypes());
		MBeanOperationInfo info = (MBeanOperationInfo) this.allowedOperations.get(key);
		if (info == null) {
			throw new InvalidInvocationException("Operation '" + method.getName() +
					"' is not exposed on the management interface");
		}

		String[] signature = null;
		synchronized (this.signatureCache) {
			signature = (String[]) this.signatureCache.get(method);
			if (signature == null) {
				signature = JmxUtils.getMethodSignature(method);
				this.signatureCache.put(method, signature);
			}
		}
		return this.server.invoke(this.objectName, method.getName(), args, signature);
	}

	/**
	 * Closes any <code>JMXConnector</code> that may be managed by this interceptor.
	 */
	public void destroy() throws Exception {
		if (this.connector != null) {
			this.connector.close();
		}
	}


	/**
	 * Simple wrapper class around a method name and its signature.
	 * Used as the key when caching methods.
	 */
	private static class MethodCacheKey {

		private final String name;

		private final Class[] parameterTypes;

		/**
		 * Create a new instance of <code>MethodCacheKey</code> with the supplied
		 * method name and parameter list.
		 * @param name the name of the method
		 * @param parameterTypes the arguments in the method signature
		 */
		public MethodCacheKey(String name, Class[] parameterTypes) {
			this.name = name;
			this.parameterTypes = (parameterTypes != null ? parameterTypes : new Class[0]);
		}

		public boolean equals(Object other) {
			if (other == null) {
				return false;
			}
			if (other == this) {
				return true;
			}
			MethodCacheKey otherKey = null;
			if (other instanceof MethodCacheKey) {
				otherKey = (MethodCacheKey) other;
				return this.name.equals(otherKey.name) && Arrays.equals(this.parameterTypes, otherKey.parameterTypes);
			}
			else {
				return false;
			}
		}

		public int hashCode() {
			return this.name.hashCode();
		}
	}

}