SimpleControllerHandlerAdapter

public class SimpleControllerHandlerAdapter implements HandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof Controller);
    }
    @Override
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        return ((Controller) handler).handleRequest(request, response);
    }
    @Override
    public long getLastModified(HttpServletRequest request, Object handler) {
        if (handler instanceof LastModified) {
            return ((LastModified) handler).getLastModified(request);
        }
        return -1L;
    }
}
public interface Controller {
    /**
     * Process the request and return a ModelAndView object which the DispatcherServlet
     * will render. A {@code null} return value is not an error: It indicates that
     * this object completed request processing itself, thus there is no ModelAndView
     * to render.
     * @param request current HTTP request
     * @param response current HTTP response
     * @return a ModelAndView to render, or {@code null} if handled directly
     * @throws Exception in case of errors
     */
    ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response) throws Exception;
}

HttpRequestHandlerAdapter

public class HttpRequestHandlerAdapter implements HandlerAdapter {
    @Override
    public boolean supports(Object handler) {
        return (handler instanceof HttpRequestHandler);
    }
    @Override
    public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        ((HttpRequestHandler) handler).handleRequest(request, response);
        return null;
    }
    @Override
    public long getLastModified(HttpServletRequest request, Object handler) {
        if (handler instanceof LastModified) {
            return ((LastModified) handler).getLastModified(request);
        }
        return -1L;
    }
}
public interface HttpRequestHandler {
    /**
     * Process the given request, generating a response.
     * @param request current HTTP request
     * @param response current HTTP response
     * @throws ServletException in case of general errors
     * @throws IOException in case of I/O errors
     */
    void handleRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException;
}

RequestMappingHandlerAdapter

public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter implements BeanFactoryAware,
        InitializingBean {
        @Override
    public final boolean supports(Object handler) {
        return handler instanceof HandlerMethod && supportsInternal((HandlerMethod) handler);
    }
@Override
    protected final ModelAndView handleInternal(HttpServletRequest request,
            HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
        if (getSessionAttributesHandler(handlerMethod).hasSessionAttributes()) {
            // Always prevent caching in case of session attribute management.
            checkAndPrepare(request, response, this.cacheSecondsForSessionAttributeHandlers, true);
        }
        else {
            // Uses configured default cacheSeconds setting.
            checkAndPrepare(request, response, true);
        }
        // Execute invokeHandlerMethod in synchronized block if required.
        if (this.synchronizeOnSession) {
            HttpSession session = request.getSession(false);
            if (session != null) {
                Object mutex = WebUtils.getSessionMutex(session);
                synchronized (mutex) {
                    return invokeHandleMethod(request, response, handlerMethod);
                }
            }
        }
        return invokeHandleMethod(request, response, handlerMethod);
    }
/**
     * This implementation always returns -1. An {@code @RequestMapping}
     * method can calculate the lastModified value, call
     * {@link WebRequest#checkNotModified(long)}, and return {@code null}
     * if the result of that call is {@code true}.
     */
    @Override
    protected long getLastModifiedInternal(HttpServletRequest request, HandlerMethod handlerMethod) {
        return -1;
    }
}
public class HandlerMethod {
    private final Object bean;
    private final Method method;
}