package com.mozilla.bespin;import org.apache.commons.lang.StringUtils;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.io.IOException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.Arrays;import java.util.HashMap;import java.util.List;import java.util.Map;public class BaseServlet extends HttpServlet {    private Map<MethodCacheKey, Method> methodCache = new HashMap<MethodCacheKey, Method>();    /**     * Dispatches a request to the appropriate handler method.     *     * @param request     * @param response     * @throws ServletException     * @throws IOException     */    @Override    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        List<String> paths = new ArrayList<String>(Arrays.asList(request.getRequestURI().toLowerCase().substring(1).split("/")));        String controllerName = StringUtils.capitalize(paths.remove(0));        Controller controller;        try {            Class controllerClazz = Class.forName("com.mozilla.bespin.controllers." + controllerName);            controller = (Controller) controllerClazz.newInstance();        } catch (ClassNotFoundException e) {            response.sendError(404, String.format("Controller \"%1$s\" not found", controllerName));            return;        } catch (Exception e) {            response.sendError(500, String.format("Controller \"%1$s\" could not be instantiated (%2$s)", controllerName, e.getClass() + ": " + e.getMessage()));            return;        }        // if there's a path element, check for a method with that name        Method method = null;        if (!paths.isEmpty()) {            method = getMethod(paths.get(0), controller.getClass());            if (method != null) paths.remove(0); // if the method was found, remove that path element from the list b/c it is not an arg        }        // if the method is still null, check for a method with the name of the HTTP method        if (method == null) method = getMethod(request.getMethod().toLowerCase(), controller.getClass());        // if the method is still null, check for a default method        if (method == null) method = getMethod("handler", controller.getClass());        if (method != null) {            RequestContext ctx = new RequestContext(this, request, response, paths);            controller.setCtx(ctx);            try {                if (method.isAnnotationPresent(RequiresLogin.class)) {                    if (!controller.isAuthenticated()) {                        response.sendError(401, "You're not logged in, and this request requires you to be");                        return;                    }                }                // if there are any parameters, it'll be for a single RequestContext instance                if (method.getParameterTypes().length != 0) {                    method.invoke(controller, ctx);                } else {                    method.invoke(controller);                }            } catch (Exception e) {                response.sendError(500, String.format("Error invoking method for request"));                return;            }        } else {            response.sendError(400, String.format("Couldn't map request \"%1$s\" to a controller/method", request.getRequestURI()));        }    }    private Method getMethod(String methodName, Class<? extends Object> controllerClass) {        MethodCacheKey key = new MethodCacheKey(controllerClass, methodName);        Method m = methodCache.get(key);        if (m != null) return m;        m = getMethodReflectively(methodName, controllerClass);        if (m != null) methodCache.put(key, m);        return m;    }    private Method getMethodReflectively(String method, Class clazz) {        try {            return clazz.getMethod(method);        } catch (NoSuchMethodException e) {            // fall through to next attempt        } catch (Exception e) {            System.err.println("Unexpected exception in hasMethod");            e.printStackTrace();            return null;        }        // try a method that has a RequestContext arg        try {            return clazz.getMethod(method, RequestContext.class);        } catch (NoSuchMethodException e) {            return null;        } catch (Exception e) {            System.err.println("Unexpected exception in hasMethod");            e.printStackTrace();            return null;        }    }    private class MethodCacheKey {        private Class controller;        private String method;        private MethodCacheKey(Class controller, String method) {            this.controller = controller;            this.method = method;        }        @Override        public boolean equals(Object o) {            if (this == o) return true;            if (o == null || getClass() != o.getClass()) return false;            MethodCacheKey that = (MethodCacheKey) o;            if (!controller.equals(that.controller)) return false;            if (!method.equals(that.method)) return false;            return true;        }        @Override        public int hashCode() {            int result = controller.hashCode();            result = 31 * result + method.hashCode();            return result;        }    }}