package org.cs.core.util;

import org.apache.log4j.Logger;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
 * 
 */
public class SpringUtil implements ApplicationContextAware, DisposableBean {

	private static ApplicationContext applicationContext = null;

	private static Logger log = org.apache.log4j.Logger.getLogger(SpringUtil.class);
	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	public void setApplicationContext(ApplicationContext applicationContext) {
		log.debug("注入ApplicationContext到SpringContextHolder:" + applicationContext);

		if (SpringUtil.applicationContext != null) {
			log.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:"
					+ SpringUtil.applicationContext);
		}

		SpringUtil.applicationContext = applicationContext; //NOSONAR
	}

	/**
	 * 实现DisposableBean接口,在Context关闭时清理静态变量.
	 */
	public void destroy() throws Exception {
		SpringUtil.clear();
	}

	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		assertContextInjected();
		return applicationContext;
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	/**
	 * 清除SpringContextHolder中的ApplicationContext为Null.
	 */
	public static void clear() {
		log.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
		applicationContext = null;
	}

	/**
	 * 检查ApplicationContext不为空.
	 */
	private static void assertContextInjected() {
		if (applicationContext == null) {
			throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
		}
	}
}