list/RendererOnDemand.java

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/*
 * Turró i Cutiller Foundation. License notice.
 * Copyright (C) 2011 Lluis Turró Cutiller <http://www.turro.org/>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package  org.turro.jpa.list;
 
import java.lang.reflect.ParameterizedType;
import org.turro.jpa.Dao;
import org.zkoss.zul.Listitem;
import org.zkoss.zul.ListitemRenderer;
 
public abstract class RendererOnDemand<T, ID> implements ListitemRenderer {
 
  @Override
  public void render(Listitem item, Object data, int index) throws Exception {
    T obj = null;
    if(data.getClass().isAssignableFrom((Class<ID>) ((ParameterizedType) getClass()
            .getGenericSuperclass()).getActualTypeArguments()[1])) {
      obj = getDao().find((Class<T>) ((ParameterizedType) getClass()
            .getGenericSuperclass()).getActualTypeArguments()[0], (ID) data);
    }
    if(obj != null) {
      renderItem(item, obj);
    }
  }
  
  protected abstract Dao getDao();
  protected abstract void renderItem(Listitem item, T value);
  
}