DefaultViewResolver.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 javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.zdevra.guice.mvc.exceptions.NoViewException;
import org.zdevra.guice.mvc.exceptions.NoViewForNameException;
import org.zdevra.guice.mvc.views.JspView;
import org.zdevra.guice.mvc.views.NamedView;

import com.google.inject.ConfigurationException;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Singleton;
import com.google.inject.name.Names;

/**
 * Class provide default behaviour of a view's 
 * resolving.
 * 
 * Resolver resolves only {@link NamedView} views. All other views
 * are renderred normally. Named views are translated to concrete views.
 * In the MvcModule, you may define translation rule for each named view.
 * If there is no rule for named view, view is transformed to {@link JspView}.
 *   
 */
@Singleton
class DefaultViewResolver implements ViewResolver {

    @Inject
    private Injector injector;

    @Override
    public void resolve(ViewPoint view, ModelMap model, HttpServlet servlet, HttpServletRequest req, HttpServletResponse resp) {
        if (view == null || view == ViewPoint.NULL_VIEW) {
            throw new NoViewException(req);
        }

        if (view instanceof NamedView) {
            String viewName = ((NamedView) view).getName();
            try {
                view = injector.getInstance(Key.get(ViewPoint.class, Names.named(viewName)));
            } catch (ConfigurationException e) {
                if (view == null || view == ViewPoint.NULL_VIEW) {
                    throw new NoViewForNameException(viewName);
                } else {
                    view = new JspView(viewName);
                }
            }
        }

        view.render(model, servlet, req, resp);
    }
}