requestbrokerservlet.java

主要是对串口驱动的的一些控制源码！！！ 在下载javacomm20-win32.zip后就可以使用。

		if (logger.isDebugEnabled()) {
			logger.debug("Creating ejb ...");
		}

		String jndiName = request.getJndiName();
		Object[] params = request.getParams();
		String methodName = request.getMethodName();

		Object remoteInterface = null;
		Object homeInterface = null;

		Response response = new Response();

		try {
			EJBData ejbData =
				ServerResourceManager.instance().getEJBData(jndiName);
			if (ejbData == null) {
				throw new Exception(
					"EJB with jndi name "
						+ jndiName
						+ " is not "
						+ "configured!! Please add an entry in your jkf server configuration file.");
			}

			JndiProperties props = ejbData.getJndiProperties();	
									
			Context context = new InitialContext(props.getProperties());
			Object ref = context.lookup(jndiName);

			if (ref == null) {
				throw new Exception(
					"Couldn't get a reference to ejb with jndi name "
						+ jndiName);
			}

			// Get a reference from this to the Bean's Home interface
			homeInterface =
				PortableRemoteObject.narrow(
					ref,
					Class.forName(ejbData.getHomeInterface()));

			// create a array containing the parameter classes
			Method method =
				ReflectionUtils.findMethod(
					homeInterface.getClass(),
					methodName,
					params);

			// invoke the method
			remoteInterface = method.invoke(homeInterface, params);

			// store the new object in the uses HttpSession
			RemoteObjectID remoteId = generateUniqueId();
			session.setAttribute(remoteId.toString(), remoteInterface);
			response.setRemoteObjectId(remoteId);

		} catch (Exception ex) {
			logger.error("Error creating EJB: ", ex);
			response.setRemoteException(
				new JKFCommunicationException(ex.getMessage()));
		} finally {
			return response;
		}
	}

	private Response handleEJBFindByPrimKey(
		EJBFindByPrimKeyRequest request,
		HttpSession session) {
		if (logger.isDebugEnabled()) {
			logger.debug("Trying to find ejb by primary key");
		}

		String jndiName = request.getJndiName();
		Object[] params = request.getParams();
		String methodName = request.getMethodName();

		Object remoteInterface = null;
		Object homeInterface = null;

		Response response = new Response();

		try {
			EJBData ejbData =
				ServerResourceManager.instance().getEJBData(jndiName);
			if (ejbData == null) {
				throw new Exception(
					"EJB with jndi name "
						+ jndiName
						+ " is not "
						+ "configured!! Please add an entry in your jkf server configuration file.");
			}

			JndiProperties props = ejbData.getJndiProperties();						
			Context context = new InitialContext(props.getProperties());
			Object ref = context.lookup(jndiName);
			
			if (ref == null) {
				throw new Exception(
					"Couldn't get a reference to ejb with jndi name "
						+ jndiName);
			}

			// Get a reference from this to the Bean's Home interface
			homeInterface =
				PortableRemoteObject.narrow(
					ref,
					Class.forName(ejbData.getHomeInterface()));

			// create a array containing the parameter classes
			Method method =
				ReflectionUtils.findMethod(
					homeInterface.getClass(),
					methodName,
					params);

			// invoke the method
			remoteInterface = method.invoke(homeInterface, params);

			// store the new object in the uses HttpSession
			RemoteObjectID remoteId = generateUniqueId();
			session.setAttribute(remoteId.toString(), remoteInterface);
			response.setRemoteObjectId(remoteId);

		} catch (Exception ex) {
			logger.error("Error finding ejb by primary key : ", ex);
			response.setRemoteException(
				new JKFCommunicationException(ex.getMessage()));
		} finally {
			return response;
		}
	}

	private Response handleEJBFindByXXX(
		EJBFindByXXXRequest request,
		HttpSession session) {
		if (logger.isDebugEnabled()) {
			logger.debug("Trying to find ejbs ...");
		}

		String jndiName = request.getJndiName();
		Object[] params = request.getParams();
		String methodName = request.getMethodName();

		Collection remoteInterfaces = null;
		Object homeInterface = null;

		EJBFindByXXXResponse response = new EJBFindByXXXResponse();

		try {
			EJBData ejbData =
				ServerResourceManager.instance().getEJBData(jndiName);
			if (ejbData == null) {
				throw new Exception(
					"EJB with jndi name "
						+ jndiName
						+ " is not "
						+ "configured!! Please add an entry in your jkf server configuration file.");
			}

			JndiProperties props = ejbData.getJndiProperties();						
			Context context = new InitialContext(props.getProperties());
			Object ref = context.lookup(jndiName);
			
			if (ref == null) {
				throw new Exception(
					"Couldn't get a reference to ejb with jndi name "
						+ jndiName);
			}

			// Get a reference from this to the Bean's Home interface
			homeInterface =
				PortableRemoteObject.narrow(
					ref,
					Class.forName(ejbData.getHomeInterface()));

			// create a array containing the parameter classes
			Method method =
				ReflectionUtils.findMethod(
					homeInterface.getClass(),
					methodName,
					params);

			// invoke the method
			remoteInterfaces =
				(Collection) method.invoke(homeInterface, params);

			// store the new objects in the uses HttpSession
			RemoteObjectID remoteId = null;
			Iterator it = remoteInterfaces.iterator();
			Object remoteInterface = null;
			while (it.hasNext()) {
				remoteInterface = it.next();
				remoteId = generateUniqueId();
				session.setAttribute(remoteId.toString(), remoteInterface);
				response.addRemoteObjectId(remoteId);
			}

			if (logger.isDebugEnabled()) {
				logger.debug("Leaving ...");
			}
		} catch (Exception ex) {
			logger.error("Error finding ejbs : ", ex);
			response.setRemoteException(
				new JKFCommunicationException(ex.getMessage()));
		} finally {
			return response;
		}
	}

	/*
	 * Method handleQuery. This method is called, if a client application
	 * wants to invoke any methods of a remote object.
	 * 
	 * @param datagramm - QueryRequest that holds all necessary information 
	 * 						for querying the object(id, method name, parameters)
	 * 
	 * @return Object - The QueryRequest filled with informations from 
	 * 						the method call.
	 */
	private Response handleQuery(QueryRequest datagramm, HttpSession session) {

		DataResponse response = new DataResponse();

		try {
			// retrieve the object from the session by the specified id			
			Object ob =
				session.getAttribute(datagramm.getRemoteObjectId().toString());

			// get the name of the method, that should be called
			String methodName = datagramm.getMethodName();

			// get the parameters for the method call and create an array
			// of class objects, to determin the correct method that should 
			// be called. Method itself is not serializable and declared as
			// final. Therefore we'll have to do some workaround.
			Object[] params = datagramm.getParams();
			Method method =
				ReflectionUtils.findMethod(ob.getClass(), methodName, params);

			// invoke the method and store the result in the given 
			// QueryRequest
			Object result = method.invoke(ob, params);
			response.setData(result);
		} catch (Exception ex) {
			// set the exception field of the response, if any exception
			// occures
			logger.error("Error handling query of a remote object", ex);
			response.setRemoteException(
				new JKFCommunicationException(ex.getMessage()));
		} finally {
			return response;
		}
	}

	/*
	 * Method for generating a unique RemoteObjectID
	 * that is used to identify Objets.
	 */
	private RemoteObjectID generateUniqueId() {
		return new RemoteObjectID(new UID().toString());
	}

	/*
	 * Method for handling logging messages from clients.
	 * A separate Thread is started if there are any 
	 * messages available.
	 */
	private void handleClientLogging(Request wrapper, HttpSession session) {
		Vector buffer = wrapper.getLogMessages();

		// if there are no existing messages, exit method
		if (buffer == null) {
			if (logger.isInfoEnabled()) {
				logger.info("no client log messages available");
			}

			return;
		}

		// start a Thread, that logs all messages
		ClientLoggerThread thread =
			new ClientLoggerThread(
				buffer,
				(Logger) session.getAttribute(USER_LOGGER));
		thread.start();

	}

	/*
	 * Method for handling garbage collection of remote
	 * Objects. Before the Object is removed from the 
	 * specified HttpSession, it's tried to invoke the
	 * finalize() Method of the Object if anyone 
	 * exists.
	 */
	private void handleGarbageCollection(
		Request wrapper,
		HttpSession session) {

		String id = null;

		if (logger.isInfoEnabled()) {
			logger.info("handling remote gc ...");
		}

		// get all RemoteObjectIDs for the Objects
		// that should be garbage collected
		Vector gcObjects = wrapper.getGCMessages();

		// if no remote objects needs to be garbage collected
		// exit method		
		if (gcObjects == null) {
			if (logger.isInfoEnabled()) {
				logger.info("no gc messages available");
			}

			return;
		}

		for (int i = 0; i < gcObjects.size(); i++) {

			Object o = gcObjects.elementAt(i);
			
			if(o == null) {
				System.out.println("Object that should be RemoteObjectID is null in gc thread");
			}else {
				id = ((RemoteObjectID) gcObjects.elementAt(i)).toString();

				if (logger.isInfoEnabled()) {
					logger.info("removing " + id + " from session ...");
				}

				// remove the object from session	
				session.removeAttribute(id);
			}
		}
	}

	/**
	 * This method is called if a client makes an inital registration request.
	 * This request is performed automatically by the jkf client framework, 
	 * before the user can work with the server communication framework.
	 * In the RegisterRequest is transfered a user name. The user name 
	 * is needed to generate a logger object, that is responsible for 
	 * logging messages, that are retrieved from this user and only from
	 * this user. The user name defines the file name to which this logger
	 * is logging. e.g. user name = foobar --> logging to foobar.log
	 * Therefore it would be good if the user name is unique. If not, users
	 * with the same user name log to the same logfile.
	 * 
	 * @param request	the Request object, that stores all necessary information
	 * 					for registration
	 * @param session	the HttpSession in which the user name and the generated
	 * 					Logger object is stored
	 */
	private void registerUser(RegisterRequest request, HttpSession session) {
		session.setAttribute(USER_NAME, request.getUserName());
		session.setAttribute(
			USER_LOGGER,
			ServerLoggingManager.instance().generateClientLogger(
				request.getUserName()));

	}
}