BeanCreatingHelper.java

/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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.kurento.jsonrpc.internal.server;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;

/**
 * Instantiates a target handler through a Spring {@link BeanFactory} and also provides an
 * equivalent destroy method. Mainly for internal use to assist with initializing and destroying
 * handlers with per-connection lifecycle.
 *
 * @author Rossen Stoyanchev
 * @param <T>
 * @since 4.0
 */
class BeanCreatingHelper<T> implements BeanFactoryAware {

  private static final Logger logger = LoggerFactory.getLogger(BeanCreatingHelper.class);

  private AutowireCapableBeanFactory beanFactory;

  private final Class<? extends T> beanType;
  private final String beanName;
  private Class<?> createdBeanType;

  public BeanCreatingHelper(Class<? extends T> handlerType, String beanName) {
    this.beanType = handlerType;
    this.beanName = beanName;

    this.createdBeanType = beanType;
  }

  @Override
  public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
    if (beanFactory instanceof AutowireCapableBeanFactory) {
      this.beanFactory = (AutowireCapableBeanFactory) beanFactory;
    }
  }

  public Class<?> getCreatedBeanType() {
    return this.createdBeanType;
  }

  public void setCreatedBeanType(Class<?> createdBeanType) {
    this.createdBeanType = createdBeanType;
  }

  @SuppressWarnings("unchecked")
  public T createBean() {
    if (logger.isTraceEnabled()) {
      logger.trace("Creating instance for handler type {}", this.beanType);
    }
    if (this.beanFactory == null) {
      logger.warn("No BeanFactory available, attempting to use default constructor");
      return BeanUtils.instantiate(this.beanType);
    } else {

      if (beanType != null) {
        return this.beanFactory.createBean(this.beanType);
      } else {
        T bean = (T) beanFactory.getBean(beanName);
        createdBeanType = bean.getClass();
        return bean;
      }
    }
  }

  public void destroy(T handler) {
    if (this.beanFactory != null) {
      if (logger.isTraceEnabled()) {
        logger.trace("Destroying handler instance {}", handler);
      }
      this.beanFactory.destroyBean(handler);
    }
  }

  @Override
  public String toString() {
    return "BeanCreatingHelper [beanType=" + beanType + ", beanName=" + beanName + "]";
  }
}