AbstractTemplateHandlerImpl.java

/*******************************************************************************
 * Copyright 2015 Software Evolution and Architecture Lab, University of Zurich
 * 
 * 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 eu.cloudwave.wp5.feedback.eclipse.base.infrastructure.template;

import java.io.IOException;
import java.io.StringWriter;
import java.util.Map;

import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;

/**
 * Abstract implementation of {@link TemplateHandler}.
 */
public abstract class AbstractTemplateHandlerImpl implements TemplateHandler {

  private static final String FTL = ".ftl";
  private static final String ERROR = "<ERROR INITIALIZING HOVER CONTENT>";
  protected static final String SLASH = "/";
  protected static final String TEMPLATE_LOCATION = "OSGI-INF/l10n/templates/";

  protected Configuration freemarkerConfig;

  /**
   * Freemarker {@link Configuration} freemarkerConfig of parent has to be initialized and template paths has to be set
   * according to {@see http://freemarker.org/docs/pgui_config_templateloading.html}
   */
  protected abstract void initFreemarkerConfig();

  /**
   * {@inheritDoc}
   */
  @Override
  public String getContent(final String templateName, final Map<String, Object> context) {
    try {
      if (freemarkerConfig == null) {
        initFreemarkerConfig();
      }
      final Template template = freemarkerConfig.getTemplate(TEMPLATE_LOCATION + templateName + FTL);
      final StringWriter writer = new StringWriter();
      template.process(context, writer);
      return writer.toString();
    }
    catch (final IOException | TemplateException e) {
      e.printStackTrace();
    }
    return ERROR;
  }

}