grid/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.grid;
 
import java.lang.reflect.ParameterizedType;
import java.util.function.Supplier;
import org.turro.jpa.Dao;
import org.zkoss.zul.Group;
import org.zkoss.zul.Row;
import org.zkoss.zul.RowRenderer;
 
public abstract class RendererOnDemand<T, ID> implements RowRenderer {
 
  private final Class<T> entityClass;
  private final Class<ID> idClass;
  private final Supplier<Dao> onDao;
  
  public RendererOnDemand(Supplier<Dao> onDao) {
    entityClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
    idClass = (Class<ID>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[1];
    this.onDao = onDao;
  }
 
  @Override
  public void render(Row row, Object data, int index) throws Exception {
    T obj = null;
    if(data.getClass().isAssignableFrom(idClass)) {
      obj = getDao().find(entityClass, getId((ID) data));
    } else if(data.getClass().isAssignableFrom(entityClass)) {
      obj = (T) data;
    }
    if(obj != null) {
     if(row instanceof Group) {
       renderGroup((Group) row, obj);
     } else {
      renderRow(row, obj);
     }
    }
  }
 
  protected Object getId(ID id) {
    return id;
  }
  
  protected void renderGroup(Group group, T value) {
    // nothing to do
  }
 
  protected abstract void renderRow(Row row, T value);
  
  /* Dao */
  
  private Dao dao;
  
  protected Dao getDao() {
    if(dao == null) {
      dao = onDao.get();
    }
    return dao;
  }
  
}