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How to extract the common condition check in a class

If I have a class, where all methods should evaluate only if a boolean attribute is true, what is the best way to define it in terms of best practices?
Is there a way to replace the recurring isEnabled check in all the methods by a single check? The current form works, I'm looking for a way to improve it to not have isEnabled checked in all the methods.
#Singleton
public class SomeClass implements SomeInterface {
EventPublisher eventPubilsher;
boolean isEnabled;
#Inject
public SomeClass(final Decider decider, EventPublisher, eventPublisher) {
this.isEnabled = decider.isSomethingEnabled();
this.eventPublisher = eventPublisher;
}
#Override
public void method1() {
if(isEnabled){
eventPublisher.publishSomething1();
}
}
#Override
public void method2() {
if(isEnabled){
eventPublisher.publishSomething2();
}
}
#Override
public void method3() {
if(isEnabled){
eventPublisher.publishSomething3();
}
}
}

You can have implementation for enabled stuff, and one for disabled stuff. The disabled implementation won't do anything:
public class DisabledSomeClass implements SomeInterface {
#Override
public void method1() {
}
#Override
public void method2() {
}
#Override
public void method3() {
}
}
Enabled one will publish stuff:
public class EnabledSomeClass implements SomeInterface {
EventPublisher eventPublisher;
public EnabledSomeClass(EventPublisher eventPublisher) {
this.eventPublisher = eventPublisher;
}
#Override
public void method1() {
eventPublisher.publishSomething1();
}
#Override
public void method2() {
eventPublisher.publishSomething2();
}
#Override
public void method3() {
eventPublisher.publishSomething3();
}
}
Then extract the logic, if functionality is enabled in new factory class - SomeInterfaceFactory (probably not the best name, but you get the idea), it will return the correct implementation, depending on whether something is enabled.
public class SomeInterfaceFactory {
public static SomeInterface getInstance(Decider decider, EventPublisher eventPublisher) {
if (decider.isSomethingEnabled()) {
return new EnabledSomeClass(eventPublisher);
} else {
return new DisabledSomeClass();
}
}
}

This should work
#Singleton
public class SomeClass implements SomeInterface {
EventPublisher eventPubilsher;
boolean isEnabled;
#Inject
public SomeClass(final Decider decider, EventPublisher, eventPublisher) {
this.isEnabled = decider.isSomethingEnabled();
this.eventPublisher = eventPublisher;
}
#Override
public void method1() {
publish(ep->ep.publishSomething1());
}
#Override
public void method2() {
publish(ep->ep.publishSomething2());
}
#Override
public void method3() {
publish(ep->ep.publishSomething3());
}
private void publish(Consumer<EventPublisher> callback){
if(isEnabled) callback.accept(eventPublished);
}
}

A Runnable interface can receive a lambda without args and run a lambda function with run() method. So, you can create a method inside your Decider class and receive a Runnable as a parameter, like:
class Decider{
private boolean enabled;
//...
public void execute(Runnable runnable){
if(enabled) runnable.run();
}
}
And receive your Decider and do:
//...
EventPublisher eventPubilsher;
Decider decider;
#Inject
public SomeClass(final Decider decider, EventPublisher, eventPublisher) {
this.decider = decider;
this.eventPublisher = eventPublisher;
}
#Override
public void method1() {
Decider.execute(() -> eventPublisher.publishSomething1());
}
//...

You're locking the evaluation of the condition to the constructor. If you want any flexibility, you should pull it out.
public class SomeClass implements SomeInterface {
boolean isEnabled;
public SomeClass(EventPublisher, eventPublisher) {
//
}
public void addDecide(boolean value){
isEnabled = value;
}
boolean getEnabled(){
return isEnabled;
}
#Override
public void method3() {
if(getEnabled()){
eventPublisher.publishSomething3();
}
}
}
You can even go crazy and add a supplier:
public void addDecide(Supplier<Boolean> supplier){
supplier = supplier;
}
boolean getEnabled(){
return supplier.get();
}

Factory Method return Spring service

I want a factory class that return a service that I can use to do some validations. I implemented this class
public class EventUpdateValidatorFactory {
public EventUpdateValidatorStrategy getValidator(EEventStatus eventStatus) {
if (SECOND_APPROVAL.equals(eventStatus)) {
return new EventSecondApprovalValidator();
} else if (APPROVED.equals(eventStatus)) {
return new EventApprovedValidator();
} else if (ACCOUNTING_HQ.equals(eventStatus)) {
return new EventAccountingHqValidator();
}
throw new IllegalArgumentException("Unknown status");
}
}
The interface EventUpdateValidatorStrategy is this
public interface EventUpdateValidatorStrategy {
default <T extends EventUpdateValidatorStrategy> void validate(User user, EventMasterData masterData, Event event, List<EventExternalSystemExpenseSave> expenses,
List<EventExternalSystemSpeakerSave> speakers, long eventId) {
this.validateMasterData(masterData, event);
this.validateSpeakers(speakers, eventId);
this.validateExpenses(expenses, eventId);
this.doUpdate(user, masterData, expenses, speakers, eventId);
}
void validateMasterData(EventMasterData masterData, Event event);
void validateExpenses(List<EventExternalSystemExpenseSave> expenses, long eventId);
void validateSpeakers(List<EventExternalSystemSpeakerSave> speakers, long eventId);
void doUpdate(User user, EventMasterData masterData, List<EventExternalSystemExpenseSave> expenses, List<EventExternalSystemSpeakerSave> speakers, long eventId);
}
The EventSecondApprovalValidator is this
#Service
#Transactional
public class EventSecondApprovalValidator implements EventUpdateValidatorStrategy {
#Autowired
private EventService eventService;
#Autowired
private ContextDateService contextDateService;
#Autowired
private EventExpenseService eventExpenseService;
#Autowired
private EventExternalSystemDAO eventExternalSystemDAO;
#Override
public void validateMasterData(LocalEventMasterData masterData, Event event) {
// some logic
}
#Override
public void validateExpenses(List<EventExternalSystemExpenseSave> expenses, long eventId) {
// some logic
}
#Override
public void validateSpeakers(List<EventExternalSystemSpeakerSave> speakers, long eventId) {
// some logic
}
#Override
public void doUpdate(User user, EventMasterData masterData, List<EventExternalSystemExpenseSave> expenses, List<EventExternalSystemSpeakerSave> speakers, long eventId) {
ofNullable(expenses).ifPresent(expensesToSave -> expensesToSave.forEach(expense -> this.eventExternalSystemDAO.updateExpense(user, expense)));
this.eventExternalSystemDAO.updateEvent(user, masterData, eventId);
}
}
The other EventApprovedValidator and EventAccountingHqValidator implementations are similar.
From main code I do this call
final EventUpdateValidatorStrategy validator = EventUpdateValidatorFactory.getValidator(event.getStatus());
validator.validate(user, eventSave.getMasterData(), event, eventSave.getExpenses(), eventSave.getSpeakers(), eventID);
and the result is that when I enter inside a EventSecondApprovalValidator all the autowired services are null and, obviously, I receive a NPE the first time that I use one of that service.
How I correctly use the factory to return the service that I need based on EEventStatus?

In EventUpdateValidatorFactory.getValidator(EEventStatus) method, you need to return the EventSecondApprovalValidator bean from context, instead of creating a new instance using new keyword.
The class EventSecondApprovalValidator is #Service annotated (and assuming there is only one of this type), an instance of this type will be added to ApplicationContext by Spring with all dependencies injected. So, just fetch it from context and use it.
One quick way to do this is as follows:
public EventUpdateValidatorStrategy getValidator(ApplicationContext context,
EEventStatus eventStatus) {
if (SECOND_APPROVAL.equals(eventStatus)) {
return context.getBean(EventSecondApprovalValidator.class);
} else if (APPROVED.equals(eventStatus)) {
return context.getBean(EventApprovedValidator.class);
} else if (ACCOUNTING_HQ.equals(eventStatus)) {
return context.getBean(EventAccountingHqValidator.class);
}
throw new IllegalArgumentException("Unknown status");
}
You can also #Autowire all validators in EventUpdateValidatorFactory and return the #Autowired instances. This will keep the getValidator method's signature same, but you'll have to make EventUpdateValidatorFactory a #Component-esque class.
#Component
public class EventUpdateValidatorFactory {
#Autowired
EventSecondApprovalValidator a;
#Autowired
EventApprovedValidator b;
#Autowired
EventAccountingHqValidator c;
public EventUpdateValidatorStrategy getValidator(EEventStatus eventStatus) {
if (SECOND_APPROVAL.equals(eventStatus)) {
return a;
} else if (APPROVED.equals(eventStatus)) {
return b;
} else if (ACCOUNTING_HQ.equals(eventStatus)) {
return c;
}
throw new IllegalArgumentException("Unknown status");
}

Creating an object manually you are not letting Spring perform autowiring. Consider managing your services by Spring as well.
#Component
public class MyServiceAdapter implements MyService {
#Autowired
private MyServiceOne myServiceOne;
#Autowired
private MyServiceTwo myServiceTwo;
#Autowired
private MyServiceThree myServiceThree;
#Autowired
private MyServiceDefault myServiceDefault;
public boolean checkStatus(String service) {
service = service.toLowerCase();
if (service.equals("one")) {
return myServiceOne.checkStatus();
} else if (service.equals("two")) {
return myServiceTwo.checkStatus();
} else if (service.equals("three")) {
return myServiceThree.checkStatus();
} else {
return myServiceDefault.checkStatus();
}
}
}

Replace switch-case with polymorphism

I know there are similar questions already, but looking at them I still have some doubts about how I should design my code. I have a service that allows for User registration / login /update / delete. The thing is that the User is an abstract type, which contains the data typeOfUser based on which the actual registration / update / delete methods should be called, and right now I do that in a switch-case block. I'd like to replace that with some better design.
UserController.java
public class UserController {
public UserDto register(UserDto user) {
switch(user.getTypeOfUser()) {
case DRIVER: return driverService.register(user);
case CUSTOMER: return customerService.register(user);
// ...
}
}
public UserDto update(UserDto user) {
switch(user.getTypeOfUser) {
case DRIVER: return driverService.update((DriverDto) user);
case CUSTOMER: return customerService.update((CustomerDto) user);
// ...
}
}
public UserDto login(long userId) {
loginService.login(userId);
UserBO user = userService.readById(userId);
switch(user.getTypeOfUser) {
case DRIVER: return DriverDto.fromBO((DriverBO) user);
case CUSTOMER: return CustomerDto.fromBO((CustomerBO) user);
// ...
}
}
// ...
}
I understand that something like Visitor pattern could be used, but would I really need to add the methods of registration / login /update / delete in the Enum itself? I don't really have a clear idea on how to do that, any help is appreciated.

I'd like to replace that with some better design.
The first step towards replacing the switch statement and take advantage of Polymorphism instead is to ensure that there is a single contract (read method signature) for each of the operations regardless of the user type. The following steps will explain how to achieve this :
Step 1 : Define a common interface for performing all operations
interface UserService {
public UserDto register(UserDto user);
public UserDto update(UserDto user);
public UserDto login(UserDto user)
}
Step 2 : Make UserController take a UserService as a dependency
public class UserController {
private UserService userService;
public UserController(UserService userService) {
this.userService = userService;
}
public UserDto register(UserDto user) {
userService.register(user);
}
public UserDto update(UserDto user) {
userService.update(user);
}
public UserDto login(long userId) {
userService.login(user);
}
}
Step 3 : Create subclasses to handle different types of users that take CustomerDto and CustomerBO as a dependency
class CustomerService implements UserService {
private CustomerDto userDto;
private CustomerBO userBO;
public CustomerService(UserDto userDto,UserBO userBo) {
this.userDto = (CustomerDto)userDto;
this.userBO= (CustomerBO)userBo;
}
//implement register,login and update methods to operate on userDto and userBo
}
Implement the DriverService class in a similar fashion with a dependency on DriverBo and DriverDto objects respectively.
Step 4 : Implement a runtime factory that decides which service to pass to UserController :
public UserControllerFactory {
public static void createUserController(UserDto user) {
if(user.getTypeOfUser().equals(CUSTOMER)) {
return new UserController(new CustomerService(user));
} else if(user.getTypeOfUser().equals(DRIVER)) {
return new UserController(new DriverService(user));
}
}
}
Step 5 Call the factory to create a user controller
UserDto user = someMethodThatCreatesUserDto(();
UserController controller = UserControllerFactory.createUserController(user);
controller.register();
controller.update();
controller.login();
The advantage of the above approach is that the switch/if-else statements are moved all they way back to a single class i.e the factory.

You'd want something like that:
public abstract class User {
abstract void register();
abstract void update();
abstract void login();
// maybe some more common non-abstract methods
}
Any type of User will have a class that extends this abstract class and therefore must implement all its abstract methods, like this:
public class Driver extends User {
public void register() {
// do whatever a driver does when register...
}
public void update() {
// do whatever a driver does when update...
}
public void login() {
// do whatever a driver does when login...
}
}
public class Customer extends User {
public void register() {
// do whatever a customer does when register...
}
public void update() {
// do whatever a customer does when update...
}
public void login() {
// do whatever a customer does when login...
}
}
This way, you're avoiding any switch case code. For instance, you can have an array of Users, each one them will be instantiated using new Driver() or new Customer(). Then, for example, if you're iterating over this array and executing all the Users login() method, each user's login() will be called according to its specific type ==> no switch-case needed, no casting needed!

Very simple example (only for different login logic for DriverDto and CustomerDto) - I've resigned from field typeOfUser (because it is not necessary in my solution) - I'm not sure that this is possible in your solution:
public abstract class UserDto {
// put some generic data & methods here
}
public class CustomerDto extends UserDto {
private String customerName;
public String getCustomerName() {
return customerName;
}
public void setCustomerName(String customerName) {
this.customerName = customerName;
}
}
public class DriverDto extends UserDto {
private String driverName;
public String getDriverName() {
return driverName;
}
public void setDriverName(String driverName) {
this.driverName = driverName;
}
}
public class ThisIsServiceOrDelegateToOtherServices {
public void login(CustomerDto customer) {
String name = customer.getCustomerName();
System.out.println(name);
// work on name here
}
public void login(DriverDto customer) {
String name = customer.getDriverName();
System.out.println(name);
// work on name here
}
}
Usage:
public static void main(String... args) {
//demo data
CustomerDto customer = new CustomerDto();
customer.setCustomerName("customerName");
DriverDto driver = new DriverDto();
driver.setDriverName("driverName");
// usage
ThisIsServiceOrDelegateToOtherServices service = new ThisIsServiceOrDelegateToOtherServices();
service.login(customer);
service.login(driver);
}

If you really need that TypeOfUser-enum in your UserDTO, then you could extend your enum with a serivce. So you create a TypeOfUserService interface. CustomerSerivce and DriverService will inherit from that service:
public interface TypeOfUserService {
public void register(UserDTO user);
// ...
}
public class CustomerService implements TypeOfUserService {
#Override
public void register(UserDTO user) {
// ...
}
}
public class DriverService implements TypeOfUserService {
#Override
public void register(UserDTO user) {
// ...
}
}
Then you create your register, update, etc. methods in your TypeOfUser enum:
public enum TypeOfUser {
DRIVER(new DriverService()),
CUSTOMER(new CustomerService());
private TypeOfUserService typeOfUserService;
TypeOfUser(TypeOfUserService typeOfUserService) {
this.typeOfUserService = typeOfUserService;
}
public static void register(String typeOfUser, UserDTO user) {
TypeOfUser.valueOf(typeOfUser).typeOfUserService.register(user);
}
// ...
}
You could then call the register method via:
class UserController() {
public UserDto register(UserDto user) {
TypeOfUser.register(user.getTypeOfUser, user);
}
}

Other way to achive GWTP placeManager than Constructor's #Inject annotation

I use GWTP and restyGWT. I would like to use placeManager in restyGWT DispatcherCallback, when my rest server will answer with 401 unauthorised I would like to redirect application to login page, that User could apply credentials and retried his request.
To do this I have to somehow get instance of PlaceManager (from gwtp framework). I cannot use #Inject annotation, cause I have manuall call to constructor as follow:
public class ForbiddenDispatcherFilter implements DispatcherFilter {
#Override
public boolean filter(Method method, RequestBuilder builder) {
builder.setCallback(new ForbiddenDispatcherCallback(method));
return true;
}
}
public class ForbiddenDispatcherCallback implements RequestCallback {
protected RequestCallback requestCallback;
public ForbiddenDispatcherCallback(Method method) {
this.requestCallback = method.builder.getCallback();
}
#Override
public void onResponseReceived(Request request, Response response) {
if (response.getStatusCode() == Response.SC_FORBIDDEN || response.getStatusCode() == Response.SC_UNAUTHORIZED) {
// make a hard redirect to login page
// TODO change redirect to GWTP native
Window.Location.assign("#login");
// PlaceRequest placeRequest = new
// PlaceRequest.Builder(placeManager.getCurrentPlaceRequest()).nameToken(Routing.Url.login).build();
// placeManager.revealPlace(placeRequest);
} else {
requestCallback.onResponseReceived(request, response);
}
}
public class RestyDispatcher extends DefaultFilterawareDispatcher {
public RestyDispatcher() {
addFilter(new ForbiddenDispatcherFilter());
addFilter(new BasicAuthHeaderDispatcherFilter());
}
#Override
public Request send(Method method, RequestBuilder builder) throws RequestException {
return super.send(method, builder);
}
}
Please help.
Edit
public class ClientModule extends AbstractPresenterModule {
#Override
protected void configure() {
bind(RestyGwtConfig.class).asEagerSingleton();
install(new DefaultModule.Builder()//
.defaultPlace(Routing.HOME.url)//
.errorPlace(Routing.ERROR.url)//
.unauthorizedPlace(Routing.LOGIN.url)//
.tokenFormatter(RouteTokenFormatter.class).build());
install(new AppModule());
// install(new
// GinFactoryModuleBuilder().build(AssistedInjectionFactory.class));
bind(CurrentUser.class).in(Singleton.class);
bind(IsAdminGatekeeper.class).in(Singleton.class);
bind(UserLoginGatekeeper.class).in(Singleton.class);
// Google Analytics
// bindConstant().annotatedWith(GaAccount.class).to("UA-8319339-6");
// Load and inject CSS resources
bind(ResourceLoader.class).asEagerSingleton();
}
}
and:
public class RestyGwtConfig {
static {
// GWT.log("--> RestyGwtConfig -> setDispatcher");
Defaults.setDispatcher(new RestyDispatcher());
// GWT.log("--> RestyGwtConfig -> setServiceRoot");
Defaults.setServiceRoot(new Resource(GWT.getModuleBaseURL()).resolve(ServiceRouting.SERVICE_ROOT).getUri());
UserCredentials.INSTANCE.setUserName("ronan");
UserCredentials.INSTANCE.setPassword("password");
}
}

How and where do you create your ForbiddenDispatcherFilter ?
You could use guice's AssistedInjection to inject the PlaceManager into your ForbiddenDispatcherCallback.
public class ForbiddenDispatcherCallback implements RequestCallback {
protected RequestCallback requestCallback;
protected PlaceManager placeManager;
#Inject
public ForbiddenDispatcherCallback(PlaceManager placeManager, #Assisted Method method) {
this.placeManager = placeManager;
this.requestCallback = method.builder.getCallback();
}
}
You need to define an factory interface:
public interface AssistedInjectionFactory {
ForbiddenDispatcherCallback createForbiddenCallback(Method method);
}
In the configure method of your ClientModule you need to call:
install(new GinFactoryModuleBuilder().build(AssistedInjectionFactory.class));
Then you can instantiate your class this way:
public class ForbiddenDispatcherFilter implements DispatcherFilter {
AssistedInjectionFactory factory;
#Inject
public ForbiddenDispatcherFilter(AssistedInjectionFactory factory)
{
this.factory = factory;
}
#Override
public boolean filter(Method method, RequestBuilder builder) {
builder.setCallback(factory.AssistedInjectionFactory(method))
return true;
}
}
Of course this requires that you also inject the ForbiddenDispatcherFilter.
Edit:
You could try to pass the RestyDispatcher to the constructor of your RestyGWTConfig:
public class RestyGwtConfig {
#Inject
public RestyGwtConfig(RestyDispatcher dispatcher) {
Defaults.setDispatcher(dispatcher);
}
static {
// GWT.log("--> RestyGwtConfig -> setServiceRoot");
Defaults.setServiceRoot(new Resource(GWT.getModuleBaseURL()).resolve(ServiceRouting.SERVICE_ROOT).getUri());
UserCredentials.INSTANCE.setUserName("ronan");
UserCredentials.INSTANCE.setPassword("password");
}
}
The RestyDispatcher looks like this:
public class RestyDispatcher extends DefaultFilterawareDispatcher {
#Inject
public RestyDispatcher(ForbiddenDispatcherFilter filter) {
addFilter(filter);
addFilter(new BasicAuthHeaderDispatcherFilter());
}
#Override
public Request send(Method method, RequestBuilder builder) throws RequestException {
return super.send(method, builder);
}
}

Java - Execute a class method with a specify annotation

I have a android application, but it is not relevant.
I have a class called "Front controller" which will receive some message
through it's constructor. The message, for brievity, could be an integer.
I want somewhere else to create a new controller which will execute
a method based on the integer defined above
public class OtherController {
#MessageId("100")
public void doSomething(){
//execute this code
}
#MessageId("101")
public void doSomethingElse(){
//code
}
}
The front controller could be something like this:
public class FrontController {
private int id;
public FrontController(int id){
this.id=id;
executeProperControllerMethodBasedOnId();
}
public void executeProperControllerMethodBasedOnId(){
//code here
}
public int getId(){
return id;
}
}
So, if the Front Controller will receive the integer 100, it
will execute the method annotated with #MessageId(100). The
front controller don't know exactly the class where this method
is.
The problem which I found is that I need to register somehow
each controller class. I Spring I had #Component or #Controller
for autoloading. After each controllers are register, I need to
call the properly annotated method.
How to achieve this task? In Spring MVC, I had this system
implemented, used to match the HTTP routes. How could I implement
this in a plain java project?
Any suggestions?

Thanks to Google Reflections (hope you can integrate this in your android project.)
<dependency>
<groupId>org.reflections</groupId>
<artifactId>reflections-maven</artifactId>
<version>0.9.8</version>
</dependency>
For optimisation I've added the requirement to also annotate the class with MessageType annotation and the classes should be in the same package (org.conffusion in my example):
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.TYPE)
public #interface MessageType {
}
The OtherController looks like:
#MessageType
public class OtherController {
#MessageId(id=101)
public void method1()
{
System.out.println("executing method1");
}
#MessageId(id=102)
public void method2()
{
System.out.println("executing method2");
}
}
The implementation will look like:
public void executeProperControllerMethodBasedOnId() {
Set<Class<?>> classes = new org.reflections.Reflections("org.conffusion")
.getTypesAnnotatedWith(MessageType.class);
System.out.println("found classes " + classes.size());
for (Class<?> c : classes) {
for (Method m : c.getMethods()) {
try {
if (m.isAnnotationPresent(MessageId.class)) {
MessageId mid = m.getAnnotation(MessageId.class);
Object o = c.newInstance();
if (mid.id() == id)
m.invoke(o);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
Maybe you can optimise and build a static hashmap containing already scanned message ids.

You need to implement some of the work by yourself using reflection, I would recommend to prepare message handlers on initial phase in regards to performance. Also you possibly want to think about Singleton/Per Request controllers. Some of the ways to implement the solution:
interface MessageProcessor {
void execute() throws Exception;
}
/* Holds single instance and method to invoke */
class SingletonProcessor implements MessageProcessor {
private final Object instance;
private final Method method;
SingletonProcessor(Object instance, Method method) {
this.instance = instance;
this.method = method;
}
public void execute() throws Exception {
method.invoke(instance);
}
}
/* Create instance and invoke the method on execute */
class PerRequestProcessor implements MessageProcessor {
private final Class clazz;
private final Method method;
PerRequestProcessor(Class clazz, Method method) {
this.clazz = clazz;
this.method = method;
}
public void execute() throws Exception {
Object instance = clazz.newInstance();
method.invoke(instance);
}
}
/* Dummy controllers */
class PerRequestController {
#MessageId(1)
public void handleMessage1(){System.out.println(this + " - Message1");}
}
class SingletonController {
#MessageId(2)
public void handleMessage2(){System.out.println(this + " - Message2");}
}
class FrontController {
private static final Map<Integer, MessageProcessor> processors = new HashMap<Integer, MessageProcessor>();
static {
try {
// register your controllers
// also you can scan for annotated controllers as suggested by Conffusion
registerPerRequestController(PerRequestController.class);
registerSingletonController(SingletonController.class);
} catch (Exception e) {
throw new ExceptionInInitializerError();
}
}
private static void registerPerRequestController(Class aClass) {
for (Method m : aClass.getMethods()) {
if (m.isAnnotationPresent(MessageId.class)) {
MessageId mid = m.getAnnotation(MessageId.class);
processors.put(mid.value(), new PerRequestProcessor(aClass, m));
}
}
}
private static void registerSingletonController(Class aClass) throws Exception {
for (Method m : aClass.getMethods()) {
if (m.isAnnotationPresent(MessageId.class)) {
MessageId mid = m.getAnnotation(MessageId.class);
Object instance = aClass.newInstance();
processors.put(mid.value(), new SingletonProcessor(instance, m));
}
}
}
/* To process the message you just need to look up processor and execute */
public void processMessage(int id) throws Exception {
if (processors.containsKey(id)) {
processors.get(id).execute();
} else {
System.err.print("Processor not found for message " + id);
}
}
}