ClassScanner.java

/*****************************************************************************
 * Copyright 2011 Zdenko Vrabel
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 *****************************************************************************/
package org.zdevra.guice.mvc;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

import org.zdevra.guice.mvc.annotations.Controller;
import org.zdevra.guice.mvc.annotations.DELETE;
import org.zdevra.guice.mvc.annotations.GET;
import org.zdevra.guice.mvc.annotations.HEAD;
import org.zdevra.guice.mvc.annotations.Model;
import org.zdevra.guice.mvc.annotations.POST;
import org.zdevra.guice.mvc.annotations.PUT;
import org.zdevra.guice.mvc.annotations.Path;
import org.zdevra.guice.mvc.exceptions.ScannerException;

import com.google.inject.Injector;

/**
 * The method provide scanning of Controller class
 * and produce the invoker for controller. It's factory
 * class for {@link ClassInvoker}
 *
 * @see ClassInvoker
 */
class ClassScanner {

    /**
     * Method do scanning of controller's class and produce
     * {@link ClassInvoker} object
     * 
     * @param controllerClass
     * @param injector
     * 
     * @return instance of the class invoker for annotated class.
     * @throws Exception
     */
    public ClassInvoker scan(Class<?> controllerClass, Injector injector) {
        try {
            InterceptorService interceptorService = injector.getInstance(InterceptorService.class);
            if (interceptorService == null) {
                throw new IllegalStateException("The InterceptorService doesn't exists in guice module");
            }

            Controller controllerAnotation = controllerClass.getAnnotation(Controller.class);
            if (controllerAnotation == null) {
                throw new IllegalStateException("Class is not defined as a controller. Missing @Controller annotation.");
            }

            //scan session attributes & default view
            List<String> sessionAttrList = Arrays.asList(controllerAnotation.sessionAttributes());

            //scan methods
            List<Method> methods = Arrays.asList(controllerClass.getMethods());
            List<MethodInvoker> scannedInvokers = new LinkedList<MethodInvoker>();
            for (Method method : methods) {
                MappingData reqMappingData = mappingDataForNewAnot(method);
                if (reqMappingData == null) {
                    reqMappingData = mappingDataForNewAnot(method);
                }

                if (reqMappingData != null) {
                    reqMappingData.injector = injector;
                    reqMappingData.controllerClass = controllerClass;
                    reqMappingData.method = method;

                    //create the invoker
                    MethodInvoker invoker = MethodInvokerImpl.createInvoker(reqMappingData);

                    //at the end is filter decorator
                    MethodInvoker filteredInvoker = new MethodInvokerFilter(reqMappingData, invoker);
                    scannedInvokers.add(filteredInvoker);
                }
            }

            if (scannedInvokers != null) {
                Collections.sort(scannedInvokers);
            }

            return new ClassInvoker(controllerClass, scannedInvokers, sessionAttrList);
        } catch (Exception e) {
            throw new ScannerException(controllerClass, e);
        }
    }

    /**
     * new version of mapping annotations
     */
    private MappingData mappingDataForNewAnot(Method method) {
        Path path = method.getAnnotation(Path.class);
        if (path == null) {
            return null;
        }

        MappingData reqMapping = new MappingData(
                null,
                null,
                HttpMethodType.ALL,
                path.value(),
                method.getName(),
                null);

        Model resultName = method.getAnnotation(Model.class);
        if (resultName != null) {
            reqMapping.resultName = resultName.value();
        }

        //resolve HTTP method
        if (method.getAnnotation(GET.class) != null) {
            reqMapping.httpMethodType = HttpMethodType.GET;
        } else if (method.getAnnotation(POST.class) != null) {
            reqMapping.httpMethodType = HttpMethodType.POST;
        } else if (method.getAnnotation(PUT.class) != null) {
            reqMapping.httpMethodType = HttpMethodType.PUT;
        } else if (method.getAnnotation(DELETE.class) != null) {
            reqMapping.httpMethodType = HttpMethodType.DELETE;
        } else if (method.getAnnotation(HEAD.class) != null) {
            reqMapping.httpMethodType = HttpMethodType.HEAD;
        } else {
            reqMapping.httpMethodType = HttpMethodType.ALL;
        }

        return reqMapping;
    }
}