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2021
11-01

解决SpringMvc中普通类注入Service为null的问题

SpringMvc中普通类注入Service为null

场景：

使用Quartz定时器时,普通的java类需要注入spring的service类,在调用时报错!

解决方式：

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/**
 * 定时获取课程的service
 */
@Autowired
protected QuartzGetCourseService quartzGetCourseService = (QuartzGetCourseService) SpringContextUtil
        .getBean("quartzGetCourseService");
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import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
  
/**
 * 在Spring 注解中，普通类获取@Service标记的方法或者bean对象
 *
 */
@Component
public class SpringContextUtil implements ApplicationContextAware {
    private static ApplicationContext applicationContext = null;
  
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextUtil.applicationContext = applicationContext;
    }
  
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
  
    /**
     * 注意 bean name默认 = 类名(首字母小写) 例如: A8sClusterDao = getBean("a8sClusterDao")
     *
     * @param name
     * @return
     * @throws BeansException
     */
    public static Object getBean(String name) throws BeansException {
        return applicationContext.getBean(name);
    }
  
    /**
     * 根据类名获取到bean
     *
     * @param <T>
     * @param clazz
     * @return
     * @throws BeansException
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBeanByName(Class<T> clazz) throws BeansException {
        try {
            char[] cs = clazz.getSimpleName().toCharArray();
            cs[0] += 32;// 首字母大写到小写
            return (T) applicationContext.getBean(String.valueOf(cs));
        }
        catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
  
    public static boolean containsBean(String name) {
        return applicationContext.containsBean(name);
    }
  
    public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
        return applicationContext.isSingleton(name);
    }
}

调用结束，测试可以获取Service.

spring之工具类使用service注入

一般需要在一个工具类中使用@Autowired 注解注入一个service。但是由于工具类方法一般都写成static，所以直接注入就存在问题。

栗子:

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@Component 
public class SmsController {   
    private static Logger logger = LoggerFactory.getLogger(SmsController.class);   
    @Autowired 
    private MessagesInfoService messagesInfoService; 
    private static SmsController smsController;    
       
    @PostConstruct 
    public void init() { 
        smsController = this; 
        smsController.messagesInfoService = this.messagesInfoService;   
    } 
   
    /**
     *短信历史查询接口(查询某个时间段发送的短信)
     */
    @RequestMapping(value = "/queryMessage",method = RequestMethod.GET)
    public ModelAndView queryMessage{
        pager = messagesInfoService.findPager(map,5,pIndex);
        ModelAndView modelAndView = new ModelAndView("manage/jgdxgl/jgdx_qm");
        List<MessagesInfo> list = pager.getItem();
        modelAndView.addObject("pager",pager);
        modelAndView.addObject("list",list);
        return modelAndView
    }     
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持自学编程网。

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