ComponentManager.java :  » Web-Framework » roma-webwizard » org » romaframework » core » config » Java Open Source

/*
 * Copyright 2006 Luca Garulli (luca.garulli@assetdata.it)
 *
 * 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 org.romaframework.core.config;

import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.StringUtils;

/**
 * Generic Manager of components instantiable in one shot by setComponents
 * method (usually in configuration using Spring) and by addComponent method at
 * run-time.
 * 
 * Components will be registered with the name given from toString() call.
 * 
 * @author Luca Garulli (luca.garulli@assetdata.it)
 * 
 */
public class ComponentManager<C> {
  public ComponentManager() {
    components = new HashMap<String, C>();
  }

  /**
   * Setup multiple renders at startup
   * 
   * @param iComponentClassNames
   *          List of FrontEndRender instances to register.
   * @throws ClassNotFoundException
   * @throws IllegalAccessException
   * @throws InstantiationException
   */
  public void setComponents(List<String> iComponentClassNames) throws InstantiationException, IllegalAccessException,
      ClassNotFoundException {
    componentClassNames = iComponentClassNames;
  }

  protected void setupComponents() {
    String componentName;
    for (Iterator<String> it = componentClassNames.iterator(); it.hasNext();) {
      componentName = it.next();

      if (componentName == null || componentName.length() == 0)
        continue;

      componentName.replace('\t', ' ');
      componentName.replace('\n', ' ');
      componentName = componentName.trim();
      componentName = StringUtils.trimLeadingWhitespace(componentName);

      try {
        addComponent(componentName);
      } catch (Exception e) {
        log.error("[ComponentManager.setupComponents] Error" + e);
      }
    }
    componentClassNames = null;
  }

  /**
   * Register a single Manageable
   * 
   * @param iComponentClassName
   *          Manageable's class name
   */
  public void addComponent(String iComponentClassName) throws InstantiationException, IllegalAccessException,
      ClassNotFoundException {
    addComponent(Class.forName(iComponentClassName));
  }

  /**
   * Register a single Manageable
   * 
   * @param iComponentClass
   *          Manageable's class
   */
  public void addComponent(Class iComponentClass) throws InstantiationException, IllegalAccessException {
    // INSTANTIATE THE COMPONENT
    C component = (C) iComponentClass.newInstance();

    // REGISTER THE COMPONENT INSTANCE WITH ITS NAME (GIVEN FROM toString()
    // METHOD)
    components.put(component.toString(), component);
  }

  /**
   * Register a single Component
   * 
   * @param iComponentClassName
   *          Manageable's class name
   */
  public void addComponentInstance(C iComponentInstance) {
    // REGISTER THE COMPONENT INSTANCE WITH ITS NAME (GIVEN FROM toString()
    // METHOD)
    addComponentInstance(iComponentInstance.toString(), iComponentInstance);
  }

  /**
   * Register a single Component
   * 
   * @param iComponentClassName
   *          Manageable's class name
   */
  public void addComponentInstance(String iComponentName, C iComponentInstance) {
    // REGISTER THE COMPONENT INSTANCE WITH ITS NAME (GIVEN FROM toString()
    // METHOD)
    components.put(iComponentName, iComponentInstance);
  }

  public Set<String> getComponentNames() {
    if (componentClassNames != null) {
      synchronized (components) {
        if (componentClassNames != null)
          setupComponents();
      }
    }
    return components.keySet();
  }

  /**
   * Get the render by the key
   * 
   * @param iKey
   *          String that identify the render (the same that FrontEndRender
   *          instance uses to register to the PluginManager
   * @return FrontEndRender if found, otherwise null
   */
  public C getComponent(String iKey) {
    if (componentClassNames != null) {
      synchronized (components) {
        if (componentClassNames != null)
          setupComponents();
      }
    }
    return components.get(iKey);
  }

  protected List<String>    componentClassNames;
  protected Map<String, C>  components;

  protected static Log      log  = LogFactory.getLog(ComponentManager.class);
}