Registry.java

/**
 * MIT License
 *
 * Copyright (c) 2017 TRIOLOGY GmbH
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */


package de.triology.cb.spring;

import de.triology.cb.Command;
import de.triology.cb.CommandHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.core.GenericTypeResolver;

import java.util.HashMap;
import java.util.Map;

/**
 * Registry holds the mapping between a command and its handler. The registry should always be injected, by the spring
 * framework.
 */
public class Registry {

  private Map<Class<? extends Command>, CommandProvider> providerMap = new HashMap<>();

  @Autowired
  public Registry(ApplicationContext applicationContext) {
    String[] names = applicationContext.getBeanNamesForType(CommandHandler.class);
    for (String name : names) {
      register(applicationContext, name);
    }
  }

  private void register( ApplicationContext applicationContext, String name ){
    Class<CommandHandler<?,?>> handlerClass = (Class<CommandHandler<?,?>>) applicationContext.getType(name);
    Class<?>[] generics = GenericTypeResolver.resolveTypeArguments(handlerClass, CommandHandler.class);
    Class<? extends Command> commandType = (Class<? extends Command>) generics[1];
    providerMap.put(commandType, new CommandProvider(applicationContext, handlerClass));
  }

  @SuppressWarnings("unchecked")
  <R, C extends Command<R>> CommandHandler<R,C> get(Class<C> commandClass) {
    return providerMap.get(commandClass).get();
  }

}