SpringContextHolder获取bean实例

package com.bandweaver.tunnel.common.platform.util;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import com.bandweaver.tunnel.common.platform.log.LogUtil;

public class SpringContextHolder implements ApplicationContextAware {

	private static ApplicationContext applicationContext = null;


	/**
	 * 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 getBean(String name) {
		LogUtil.debug("从SpringContextHolder中取出Bean:" + 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 getBean(Class requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

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

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) {
//		LogUtil.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);

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

		SpringContextHolder.applicationContext = applicationContext; // NOSONAR
	}

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

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