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    <p>I guess this would be the perfect use case for </p> <ol> <li>Java Dynamic Proxys</li> <li>Thread locals</li> </ol> <p>To elucidate:</p> <p>First, create your Facade Interface :</p> <pre> interface UserServiceFacede { List findUsers(UserSearchParameters searchParameters, PagingParameters pagingParameters) throws AuthenticationFault, InvalidIndexFault; void removeUser(User userToRemove) throws AutheticationFault; void addUser(User newUser) throws AuthenticationFault; } </pre> <p>Next you implement your InvocationHandler :</p> <pre> public class UserHandler implements InvocationHandler{ private final UserService service; public UserHandler(UserService service) { this.service = service; } public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { .... // Based on the method argument, call the appropriate function on the actual service // object .... } } </pre> <p>You then create the Proxy object like so :</p> <pre> UserServiceFacade uProxy = (UserServiceFacade)Proxy.newProxyInstance(UserHandler.class.getClassLoader(), new Class[] { UserServiceFacade.class}, new UserHandler(userService)); </pre> <p>The first argument is the classloader, the second is the list of interfaces the Proxy must confirm to and the third is the handler object</p> <p>Now the question is how do you get a handle onto your loggedinUser. This is where <a href="http://download.oracle.com/javase/6/docs/api/java/lang/ThreadLocal.html" rel="nofollow">ThreadLocal</a> comes in.</p> <p>Create a ThreadLocal static variable that holds the loggedin user. Then set the current user into the ThreadLocal before invoking the proxy</p> <pre> private static final ThreadLocal loggedinUser = ...; ... ... loggedinUser.set(currentUser); // Create a user Proxy object as mentioned above.. uProxy.findUser(searchParams, ..); ... </pre> <p>Retrieve the User from the ThreadLocal inside the invoke function of the handler. Now inside the handler, you have access to both the loggedinUser (using <code>loggedinUser.get()</code>) as well as the user service object (You have passed in the service object into your handler's constructor)</p> <p>As far as how you handle exceptions are concerned, WHat I would do is generally keep throwing a subclass of RuntimeExceptions. Then catch these at the periphery layer of your app. By periphery layer I mean, entry point into your app/library. If you were developing a webbApp this would be your Servlet.</p>
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    1. CODon't worry, retrieving the currently logged in user is not an issue.
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    2. COOh.. but did the proxy solution work for u ?
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