spring boot工作流listener监听器获取@Autowired对象Bean为null的解决方案

╰+攻爆jí腚メ 2022-04-24 10:58 713阅读 0赞

背景：使用工作流监听器监听流程结束后处理业务，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；

解决：

1）新建获取bean的类

package com.ww.activiti.config;
    
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.beans.factory.DisposableBean;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.context.annotation.Configuration;
    
    /**
     * 上下文管理
     *
     * @author: Ace Lee
     * @create: 2019-04-22 15:24
     */
    @Slf4j
    @Configuration
    public class SpringContextHolder implements ApplicationContextAware, DisposableBean {
    
        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> T getBean(String name) {
            log.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> T getBean(Class<T> requiredType) {
            assertContextInjected();
            return applicationContext.getBean(requiredType);
        }
    
        /**
         * 清除SpringContextHolder中的ApplicationContext为Null.
         */
        public static void clearHolder() {
            log.info("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) {
    //		logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);
    
            if (SpringContextHolder.applicationContext != null) {
                log.warn("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.
         */
        @Override
        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或在SpringBoot启动类中注册SpringContextHolder.");
            }
        }
    }

2）监听器里获取service，使用getBean(XXX.class)

//这里要注意用@AutoWired注解是获取不到bean的对象
                    KafkaSender sender = SpringContextHolder.getBean(KafkaSender.class);
                   
                    sender.asyncSendMessage("ww_test",proInsId,JacksonUtil.bean2Json(bussData));

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