GuiceBootstrap.java

/*
 * Copyright (c) 2012, Inversoft Inc., All Rights Reserved
 *
 * 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.primeframework.mvc.guice;

import java.io.Closeable;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.primeframework.mvc.PrimeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.inject.Binding;
import com.google.inject.CreationException;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Scopes;
import com.google.inject.spi.Message;

/**
 * This class bootstraps Guice.
 *
 * @author Brian Pontarelli
 */
public class GuiceBootstrap {
  private static final Logger logger = LoggerFactory.getLogger(GuiceBootstrap.class);

  /**
   * Please do not invoke this method unless you know what you are doing. This initializes Guice and does it once only
   * so that synchronization is not used. This is called by the PrimeServletContextListener when the context is created
   * and should cover all cases.
   *
   * @param mainModule The main module for the application.
   * @return The Guice injector.
   */
  public static Injector initialize(Module mainModule) {
    logger.debug("Initializing Guice");
    try {
      return Guice.createInjector(mainModule);
    } catch (CreationException e) {
      logger.debug("Unable to create Guice injector", e);

      Collection<Message> messages = e.getErrorMessages();
      Set<String> errorMessages = new HashSet<>();
      messages.forEach((message) -> {
        if (message.getCause() != null) {
          errorMessages.add("[" + message.getMessage() + "] \n\t-> [" + message.getCause().getClass() + "] " + message.getCause().getMessage());
        } else {
          errorMessages.add("[" + message.getMessage() + "]");
        }
      });
      logger.error(
          "\n\n===================================================================================================\n\n" +
              "  Unable to start the server. Here's why: \n\n\n" + String.join("\n", errorMessages) +
              "\n\n===================================================================================================\n\n"
      );
      logger.debug("Unable to start the server. Exception: \n", e);
      throw new PrimeException();
    }
  }

  /**
   * Shuts down the Guice injector by locating all of the {@link Closeable} singletons classes and calling Close on each
   * of them.
   *
   * @param injector The Injector to shutdown.
   */
  public static void shutdown(Injector injector) {
    Map<Key<?>, Binding<?>> bindings = injector.getBindings();
    for (Key<?> key : bindings.keySet()) {
      Type type = key.getTypeLiteral().getType();
      if (type instanceof ParameterizedType) {
        type = ((ParameterizedType) type).getRawType();
      }

      if (type instanceof Class) {
        Class<?> bindingType = (Class<?>) type;
        if (Closeable.class.isAssignableFrom(bindingType) && Scopes.isSingleton(bindings.get(key))) {
          Closeable closable = (Closeable) injector.getInstance(key);
          try {
            closable.close();
          } catch (Throwable t) {
            logger.error("Unable to shutdown Closeable [" + key + "]");
          }
        }
      }
    }
  }
}