Non invasive GWT and Spring integration

(...)
...)
 
log4jConfigLocation
/WEB-INF/log4j.xml
 
contextConfigLocation
classpath:/META-INF/spring-conf.xml
 
			org.springframework.web.util.Log4jConfigListener
 
			org.springframework.web.context.ContextLoaderListener
 
			org.springframework.web.context.request.RequestContextListener
 
(...)

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
/**
 * Annotation used to flag auto injection.
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(value = ElementType.METHOD)
public @interface AutoInject {
 
}

import java.lang.reflect.Method;
 
import javax.servlet.ServletException;
 
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
 
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
 
/**
 * Provides automatic injection into GWT services. Only setter methods with exactly one parameter and
 * annotated with AutoInject will be considered for auto injection.
 *
 */
public abstract class AutoInjectingRemoteServiceServlet extends RemoteServiceServlet {
 
    /**
     * Logger.
     */
    private static final Logger LOG = LoggerFactory.getLogger(AutoInjectingRemoteServiceServlet.class);
 
    /** Reference for the WebApplicationContext. */
    private WebApplicationContext ctx;
 
    /**
     * {@inheritDoc}
     */
    @Override
    public void init() throws ServletException {
        LOG.debug("Initializing servlet");
        super.init();
        LOG.debug("Get reference to the Spring Application Context");
        ctx = WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());
        System.out.println(ctx);
        LOG.debug("Spring ctx with: {} beans.", ctx.getBeanDefinitionCount());
        this.populateVariables();
    }
 
    /**
     * Performs auto injection on this servlet instance.
     */
    @SuppressWarnings("unchecked")
    private void populateVariables() {
        LOG.debug("Start servlet auto injection");
        Method[] methods = this.getClass().getMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
 
            if (method.getName().startsWith("set") && method.isAnnotationPresent(AutoInject.class)
                    && method.getParameterTypes().length == 1) {
                Class type = method.getParameterTypes()[0];
                LOG.debug("Looking for: {}", type);
                String[] beanNamesForType = ctx.getBeanNamesForType(type, false, true);
                LOG.debug("Got {} with {} elements", beanNamesForType, beanNamesForType.length);
                if (beanNamesForType.length != 1) {
                    LOG.error("There is no bean of type {} for autoinjection", type.toString());
                } else {
                    try {
                        method.invoke(this, ctx.getBean(beanNamesForType[0]));
                        LOG.info("Injected bean: {} on field {} ", beanNamesForType[0], this.getClass().getName());
                    } catch (Throwable e) {
                        LOG.error("Error: could not inject into " + "protected variable {}, cause: {}", method.getName(), e
                                .getMessage());
                        if (LOG.isDebugEnabled()) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }
}

public class GwtLoginServiceImpl extends AutoInjectingRemoteServiceServlet implements GwtLoginService {
 
	private ILoginService loginService;
 
	@AutoInject
	public void setLogService(ILoginService loginService) {
		this.loginService = loginService;
	}
 
	@Override
	public LoginResult doLogin(String username, String password) {
		LoginResult result = new LoginResult();
		try {
			result.loggedInUser = loginService.doLogin(username, password);
			result.successFull = true;
		} catch (BadCredentialsException bce) {
			result.successFull = false;
			result.errorMessage = "Bad credentials.";
		} catch (Throwable t) {
			result.successFull = false;
			result.errorMessage = "Server error.";
		}
		return result;
	}
 
	@Override
	public UserDTO isLoggedIn() {
		return loginService.isLoggedIn();
	}
 
	@Override
	public void doLogout() {
		loginService.doLogout();
	}
}