org.tangram.components.spring.SpringViewUtilities.java Source code

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Here is the source code for org.tangram.components.spring.SpringViewUtilities.java

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/**
 *
 * Copyright 2011-2014 Martin Goellnitz
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 */
package org.tangram.components.spring;

import java.io.IOException;
import java.io.Writer;
import java.util.Locale;
import java.util.Map;
import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.View;
import org.tangram.Constants;
import org.tangram.spring.view.ViewHandler;
import org.tangram.view.RequestParameterAccess;
import org.tangram.view.ViewContext;
import org.tangram.view.ViewContextFactory;
import org.tangram.view.ViewUtilities;

/**
 * Implements the inclusion mechanism of tangram by means of spring views.
 *
 * It might be a good idea to plce this in the view package hierarchy
 */
@Named("viewUtilities")
@Singleton
public class SpringViewUtilities implements ViewUtilities {

    private static final Logger LOG = LoggerFactory.getLogger(SpringViewUtilities.class);

    @Inject
    private ViewContextFactory viewContextFactory;

    @Inject
    private ViewHandler viewHandler;

    /**
     * Value to be used if there is not view in hash tables and the like where the use of null would not indicate
     * if there is no view or if we didn't look it up up to now.
     */
    public final static View NOT_FOUND_DUMMY = new View() {

        @Override
        public String getContentType() {
            return null;
        }

        @Override
        public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response)
                throws Exception {
        }

    };

    @Override
    public ViewContextFactory getViewContextFactory() {
        return viewContextFactory;
    }

    /**
     * Creates a spring request blob wrapper.
     *
     * @param request
     * @return request blob wrapper for the given request
     */
    @Override
    public RequestParameterAccess createParameterAccess(HttpServletRequest request) throws Exception {
        return new SpringRequestParameterAccess(request);
    } // createParameterAccess()

    /**
     * This is a direct converter of tangram view context to spring model and view.
     * We consider it a bug that spring's model and view is not an interfaces which would
     * make things a little bit easier and leaner to implement.
     *
     * @param viewContext
     * @return spring model and view describing exactly the same
     */
    public static ModelAndView createModelAndView(ViewContext viewContext) {
        return viewContext == null ? null : new ModelAndView(viewContext.getViewName(), viewContext.getModel());
    } // createModelAndView()

    public void render(Writer writer, Map<String, Object> model, String view) throws IOException {
        ServletRequest request = (ServletRequest) model.get(Constants.ATTRIBUTE_REQUEST);
        ServletResponse response = (ServletResponse) model.get(Constants.ATTRIBUTE_RESPONSE);

        ViewContext vc = viewContextFactory.createViewContext(model, view);
        ModelAndView mav = SpringViewUtilities.createModelAndView(vc);
        View effectiveView = mav.getView();
        LOG.debug("render() effectiveView={}", effectiveView);
        try {
            if (effectiveView == null) {
                String viewName = mav.getViewName();
                if (viewName == null) {
                    viewName = Constants.DEFAULT_VIEW;
                } // if

                effectiveView = viewHandler.resolveView(viewName, mav.getModel(), Locale.getDefault(), request);
            } // if

            if (writer != null) {
                writer.flush();
            } // if
            LOG.debug("render() model={}", mav.getModel());
            LOG.debug("render({}) effectiveView={}", mav.getViewName(), effectiveView);
            effectiveView.render(mav.getModel(), (HttpServletRequest) request, (HttpServletResponse) response);
        } catch (Exception e) {
            LOG.error("render() #" + view, e);
            if (writer != null) {
                writer.write(e.getLocalizedMessage());
            } // if
        } // try/catch
    } // render()

    @Override
    public void render(Writer writer, Object bean, String view, ServletRequest request, ServletResponse response)
            throws IOException {
        render(writer, viewContextFactory.createModel(bean, request, response), view);
    } // render()

} // SpringViewUtilities