配置springmvc在其他类中（spring容器外）获取注入bean

学习https://github.com/thinkgem/jeesite

今天在写JedisUtils的时候要注入JedisPool，而这个属性被设置为static，@Resource和@Autowired都不可以注入，因为spring不能为静态变量依赖注入。因此需要额外的方法获取spring管理的bean。本文即SpringContextHolder：

package com.demo.common.utils;

import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Service;

/**
* 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
* Created by Administrator on 2016/2/23.
*/
@Service
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware ,DisposableBean {
private static ApplicationContext applicationContext = null;
private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

/**
* 去的存储在静态变量中的ApplicationContext
* @return
*/
public static ApplicationContext getApplicationContext(){
assertContextInjected();
return applicationContext;
}

/**
* 从静态变量applicationContext中去的Bean，自动转型为所复制对象的类型
* @param name
* @param <T>
* @return
*/
public static <T> T getBean(String name){
assertContextInjected();
return (T)applicationContext.getBean(name);
}

/**
* 从静态变量applicationContext中去的Bean，自动转型为所复制对象的类型
* @param requiredType
* @param <T>
* @return
*/
public static <T> T getBean(Class<T> requiredType){
assertContextInjected();
return (T)applicationContext.getBean(requiredType);
}

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

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

/**
* 实现ApplicationContextAware接口，注入Context到静态变量
* @param applicationContext
* @throws BeansException
*/
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
SpringContextHolder.applicationContext = applicationContext;
}

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