解决无法注入spring容器，获取不到spring容器中的bean问题

解决无法注入spring容器，获取不到spring容器中的bean问题

前两天工作中遇到一个问题，收到的需求是根据logbak日志实现通过过滤错误日志发送预警邮件到邮箱，logback自定义实现类如下

/**
 * @author KyleYao
 * @date 2020/4/21 13:01
 * @description: 错误日志邮件发送
 */
@Componet
public class ErrorEmailAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {

    private final String[] TO = {"[email protected]"};

    private final String SUBJECT_PREFIX = "【Error】: ";

	@Autowired
	private MailUtils mailUtils;

    @Override
    protected void append(ILoggingEvent event) {
//        System.out.println("level =" + event.getLevel());
//        System.out.println("msg =" + event.getMessage());
//        System.out.println("level =" + event.getLevel());
        //根据规则做相应调用 TODO
        if (event.getMessage().contains("邮件")) {
            System.out.println("开始发送邮件");
            MailBean mailBean = getMailBean(event);
            MailUtils.getInstance().sendMailAttachment(mailBean);
        }
    }

    private MailBean getMailBean(ILoggingEvent event) {
        MailBean mailBean = new MailBean();
        mailBean.setTo(TO);
        mailBean.setSubject(SUBJECT_PREFIX + event.getLoggerName());
        mailBean.setContent("date = " + event.getTimeStamp() + "\n" +
                "level =" + event.getLevel() + "\n" +
                "message =" + event.getMessage() + "\n" +
                "thread = " + event.getThreadName() + "\n" +
                "logger =" + event.getLoggerName() + "\n" +
                "message =" + event.getMessage());
        return mailBean;
    }
}

因为MailUtils是通过@Service注解注入到spring容器中的，所以我这里给这个类加上@Componet注解想让他加入到容器中，这样可以获取自动注入的MailUtils，但是发现怎么也获取不到（这个原因后续研究），后来在同事帮助下使用了另一种写法，改造了一下MailUtils

@Slf4j
@Service
public class MailUtils {
	@Autowired
	private JavaMailSender javaMailSender;
	@Autowired
	private MailProperties mailProperties;

	public static MailUtils getInstance() {
		return SpringContextUtils.getBean(MailUtils.class);
	}

截取部分，通过自己封装的spring上下文工具获取到他的实体，这样在某些类无法注入到容器中时又想获得spring容器中的管理的bean的时候可以通过这种方式实现。
附：spring上下文工具如下：

/**
 * Spring上下文工具类
 * 
 * @author Andrew
 */
@Component
public class SpringContextUtils implements ApplicationContextAware {

	private static ApplicationContext applicationContext;

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		if (SpringContextUtils.applicationContext == null) {
			SpringContextUtils.applicationContext = applicationContext;
		}
	}

	public static ApplicationContext getContext() {
		return SpringContextUtils.applicationContext;
	}

	public static <T> T getBean(Class<T> beanType) {
		return applicationContext.getBean(beanType);
	}

	public static <T> T getBean(String beanName, Class<T> beanType) {
		return applicationContext.getBean(beanName, beanType);
	}

	public static Object getBean(String beanName) {
		return applicationContext.getBean(beanName);
	}

	public static ParamsProperties getParamsProperties() {
		return (ParamsProperties) getBean("paramsProperties");
	}
}