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spring boot工作流listener監聽器擷取@Autowired對象Bean為null的解決方案

背景:使用工作流監聽器監聽流程結束後處理業務,需要使用自己的service方法;

錯誤:使用@Autowired注入service對象,最終得到的為null;

解決:

1)建立擷取bean的類

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;

    /**
     * 取得存儲在靜态變量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        assertContextInjected();
        return applicationContext;
    }

    /**
     * 從靜态變量applicationContext中取得Bean, 自動轉型為所指派對象的類型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        log.debug("從SpringContextHolder中取出Bean:" + name);
        assertContextInjected();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 從靜态變量applicationContext中取得Bean, 自動轉型為所指派對象的類型.
     */
    public static <T> T getBean(Class<T> requiredType) {
        assertContextInjected();
        return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext為Null.
     */
    public static void clearHolder() {
        log.info("清除SpringContextHolder中的ApplicationContext:"
                + applicationContext);
        applicationContext = null;
    }

    /**
     * 實作ApplicationContextAware接口, 注入Context到靜态變量中.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
//		logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);

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

        SpringContextHolder.applicationContext = applicationContext; // NOSONAR
    }

    /**
     * 實作DisposableBean接口, 在Context關閉時清理靜态變量.
     */
    @Override
    public void destroy() throws Exception {
        SpringContextHolder.clearHolder();
    }

    /**
     * 檢查ApplicationContext不為空.
     */
    private static void assertContextInjected() {
        if(applicationContext == null) {
            throw new IllegalStateException("applicaitonContext屬性未注入, 請在applicationContext.xml中定義SpringContextHolder或在SpringBoot啟動類中注冊SpringContextHolder.");
        }
    }
}
           

2)監聽器裡擷取service,使用getBean(XXX.class)

//這裡要注意用@AutoWired注解是擷取不到bean的對象
                KafkaSender sender = SpringContextHolder.getBean(KafkaSender.class);
               
                sender.asyncSendMessage("ww_test",proInsId,JacksonUtil.bean2Json(bussData));
           

參考來源:https://my.oschina.net/battyman

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