EMQX监测设备上下线_eqmx

方式一、订阅系统主题
1、修改acl.conf文件配置，添加如下

{allow, all, subscribe, ["$SYS/brokers/+/clients/#"]}.
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注：要注释掉deny，它是默认阻止访问系统主题的

%%%{deny, all, subscribe, ["$SYS/#", {eq, "#"}]}.

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或者直接在图形界面

2、代码中订阅$SYS/brokers/+/clients/#主题

@PostConstruct
    public String subMessage() {
        String subTopic = "$SYS/brokers/+/clients/#";
//        String[] topic={"$SYS/brokers/+/clients/#"};
        mqttConfig.subscribe(subTopic);
        // 断开连接
        // mqttConfig.disconnect();
        return "OK";
    }
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方式二、遗嘱消息方式
1、搭建连接EQMX参考我的文章

https://blog.csdn.net/weixin_41463944/article/details/129152166?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522169924959616800227490098%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fblog.%2522%257D&request_id=169924959616800227490098&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~blog~first_rank_ecpm_v1~rank_v31_ecpm-3-129152166-null-null.nonecase&utm_term=EMQX&spm=1018.2226.3001.4450
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2、在配置文件中新增如下：

//遗嘱消息
            connOpts.setWill("deadTest","我已死亡，连接已经断开".getBytes(),qos,false);
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3、实现效果