listener中@Autowired无法注入bean的一种解决方法

背景：使用监听器处理业务，需要使用自己的service方法；

错误：使用@Autowired注入service对象，最终得到的为null；

原因：listener、fitter都不是Spring容器管理的，无法在这些类中直接使用Spring注解的方式来注入我们需要的对象。

解决：写一个bean工厂，从spring的上下文WebApplicationContext 中获取。

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
* @ClassName: SpringJobBeanFactory*/
@Component
public class SpringJobBeanFactory implements ApplicationContextAware {

    
    private static ApplicationContext applicationContext;
    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringJobBeanFactory.applicationContext=applicationContext;
        
    }
     public static ApplicationContext getApplicationContext() {
            return applicationContext;
    }
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) throws BeansException {
            if (applicationContext == null){
                return null;
            }
            return (T)applicationContext.getBean(name);
      }
    
    public static <T> T getBean(Class<T>  name) throws BeansException {
            if (applicationContext == null){
                return null;
            }
            return applicationContext.getBean(name);
      }
}

监听器里获取service，使用getBean(XXX.class)

@Override
    public void sessionDestroyed(HttpSessionEvent event) {
        logger.debug("session销毁了");
        UserCountUtils.subtract();//在线人数-1

        HttpSession session = event.getSession();// 获得Session对象
        ServletContext servletContext = session.getServletContext();

        Account acc = (Account) session.getAttribute("user");
        if(acc!=null){
            @SuppressWarnings("unchecked")
            Map<String, String> loginMap = (Map<String, String>) servletContext.getAttribute("loginMap");
            loginMap.remove(acc.getUserName());
            servletContext.setAttribute("loginMap", loginMap);
            session.removeAttribute("user");
            acc.setOnlineState(false); //注销成功修改用户在线状态为 离线
            //WebApplicationContext appctx = WebApplicationContextUtils.getWebApplicationContext(servletContext);
            //AccountService accountService = appctx.getBean(AccountService.class);
            AccountService accountService = SpringJobBeanFactory.getBean(AccountService.class);
            accountService.updateAccount(acc);
            logger.debug(acc.getUserName()+"用户注销！");
        }