EMQX文档：https://www.emqx.io/docs/zh/v5.0/

1.安装 https://www.emqx.io/zh/downloads

找到自己合适的平台和版本安装
①：后台启动

emqx start

启动成功后可以使用 emqx ping 命令检测节点运行状态，返回 pong 则表示正常运行：

emqx ping

systemctl 启动

sudo systemctl start emqx

sudo systemctl status emqx

ZIP 安装包启动
切换到 EMQX 解压目录，执行以下命令启动 EMQX：

./bin/emqx start

开发模式下可以使用 console 命令在控制台启动 EMQX，该模式可以实时查看 EMQX 启动和运行输出日志信息：

./bin/emqx console

默认监听： http://localhost:18083/
默认登录账号密码：admin public
default_username = “admin”
default_password = “public”
代码如下

 ## emqx配置
emqx:api:url: http://ip:端口/api/v4/clients/username: 用户名称password: 用户密码

	@Value("${emqx.api.url}")private String url;@Value("${emqx.api.username}")private String username;@Value("${emqx.api.password}")private String password;/***  查询网关在线离线状态* @param clientId 客户端标识符* @return 返回在线离线状态*/@Overridepublic String loadEmqxOnlineStatus(String clientId) {try {String urlStr = url + clientId;URL url = new URL(urlStr);HttpURLConnection conn = (HttpURLConnection) url.openConnection();conn.setRequestMethod("GET");conn.setDoInput(true);conn.setDoOutput(true);String authString = username + ":" + password;byte[] authEncBytes = Base64.encodeBase64(authString.getBytes());String authStringEnc = new String(authEncBytes);// 设置Authorization字段conn.setRequestProperty("Authorization", "Basic " + authStringEnc);conn.connect();int status = conn.getResponseCode();if (status == HttpStatus.OK.value()) {BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));String str = "";StringBuffer sb = new StringBuffer();while ((str = reader.readLine()) != null) {sb.append(str);}// 取出里面的在线离线字段String string = sb.toString();JSONObject jsonObject = JSONObject.parseObject(string);String data = jsonObject.getString("data");JSONArray jsonArray = JSONArray.parseArray(data);if (jsonArray.size() == 0) {return null;}return jsonArray.getJSONObject(0).getString("connected");}} catch (IOException e) {throw DataHandleException.of(Result.failure(ResultCode.UNAUTHORIZED, "客户端未通过服务端认证,您使用了无效的身份验证凭据"));}return null;}