在@Component标注的类中注入@Component标注的类

@Component
public class MsgPubMqttUtil {
 
    @Resource
    private EmqClient emqClient;
 
    @Resource
    private MqttProperties mqttProperties;
 
    @Resource
    private TMessageTemplateMapper tMessageTemplateMapper;
 
    @Resource
    private TMessageMapper tMessageMapper;
 
    private static MsgPubMqttUtil msgPubMqttUtil;
 
    @PostConstruct
    public void init(){
        msgPubMqttUtil = this;
        msgPubMqttUtil.emqClient = this.emqClient;
        msgPubMqttUtil.mqttProperties = this.mqttProperties;
        msgPubMqttUtil.tMessageTemplateMapper = this.tMessageTemplateMapper;
        msgPubMqttUtil.tMessageMapper = this.tMessageMapper;
    }
 
    /**
     * 发送消息
     * templateId 模板id
     * pubId 订阅者id
     * userType 订阅者用户类型
     * @throws Exception
     */
    public void sendMqttMessage(String templateId, String pubId, String userType) {
        // 连接服务器端
        emqClient.connect(mqttProperties.getUsername(),mqttProperties.getPassword());
        // 拼接消息主题
        StringBuffer result = new StringBuffer();
        result.append("testtopic");
        result.append("/");
        result.append(pubId);
        // 获取消息模板
        TMessageTemplate tMessageTemplate = msgPubMqttUtil.tMessageTemplateMapper.selectById(templateId);
        Map<String,String> map = new HashMap<String,String>();
        map.put("msgTemplateTitle",tMessageTemplate.getMsgTemplateTitle());
        map.put("templateContent",tMessageTemplate.getTemplateContent());
        String str = ConverUitl.getMapToString(map);
        // 发布消息
        emqClient.publish(result.toString(), str, QosEnum.QoS2,false);
        // 存入历史记录表
        TMessage tMessage = new TMessage();
        tMessage.setId(SnowflakeIdWorkerUtil.nextId());
        tMessage.setCreated(new Date());
        tMessage.setUpdated(new Date());
        tMessage.setReadStatus("1");  // 设置为未读
        tMessage.setMsgTitle(map.get("msgTemplateTitle"));
        tMessage.setMsgContent(map.get("templateContent"));
        tMessage.setUserType(userType);  // 接收者类型
        tMessage.setUserId(pubId);  // 接收者主键
        tMessage.setMtId(templateId);  // 关联的模板id
        tMessageMapper.insert(tMessage);
    }
 
}