View.java

package act.view;

/*-
 * #%L
 * ACT Framework
 * %%
 * Copyright (C) 2014 - 2017 ActFramework
 * %%
 * 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.
 * #L%
 */

import act.Act;
import act.app.App;
import act.app.event.AppEventId;
import act.plugin.AppServicePlugin;
import act.util.ActContext;
import org.osgl.http.H;
import org.osgl.util.C;
import org.osgl.util.IO;
import org.osgl.util.S;

import java.io.File;
import java.util.List;

/**
 * The base class that different View solution should extends
 */
public abstract class View extends AppServicePlugin {

    /**
     * Returns the View solution's name. Recommended name should
     * be in lower case characters. E.g. freemarker, velocity,
     * rythm etc
     */
    public abstract String name();

    @Override
    protected void applyTo(final App app) {
        Act.viewManager().register(this);
        app.jobManager().on(AppEventId.CLASS_LOADER_INITIALIZED, new Runnable() {
            @Override
            public void run() {
                init(app);
            }
        });
    }

    public boolean appliedTo(ActContext context) {
        H.Format format = context.accept();
        return format.isText();
    }

    /**
     * Sub class must implement this method to load the template
     *
     * @param resourcePath the path to the template
     * @param context      the view context
     * @return the template instance or {@code null} if template not found
     */
    protected abstract Template loadTemplate(String resourcePath, ActContext context);

    /**
     * Sub class could use this method initialize the implementation
     */
    protected void init(App app) {
    }

    protected void reload(App app) {
        init(app);
    }

    protected final String templateHome() {
        String templateHome = Act.appConfig().templateHome();
        if (S.blank(templateHome) || "default".equals(templateHome)) {
            templateHome = "/" + name();
        }
        return templateHome;
    }

    /**
     * Load template content.
     *
     * This method is used by error reporting feature when app running in dev mode
     * @param template the template path
     * @return the template content in lines
     */
    public List<String> loadContent(String template) {
        File file = new File(templateRootDir(), template);
        if (file.exists() && file.canRead()) {
            return IO.readLines(file);
        }
        return C.list();
    }


    protected final File templateRootDir() {
        App app = Act.app();
        return new File(app.layout().resource(app.base()), templateHome());
    }
}