✨ mica-mqttx-client 支持 `reconnect(String ip, int port)` 转移到其他服务，订阅保留，连接成功时自动重新订阅。

mica-mqtt-client/src/main/java/net/dreamlu/iot/mqtt/core/client/DefaultMqttClientProcessor.java

@@ -75,8 +75,8 @@ public class DefaultMqttClientProcessor implements IMqttClientProcessor {
 				}
 				// 2. 发布连接通知
 				publishConnectEvent(context);
-				// 3. 如果 session 不存在重连时发送重新订阅
-				if (!connAckVariableHeader.isSessionPresent()) {
+				// 3. 如果 session 不存在重连时发送重新订阅，更改 ip、端口之后需要重新发送订阅
+				if (!connAckVariableHeader.isSessionPresent() || MqttClient.isNeedReSub(context)) {
 					reSendSubscription(context);
 				}
 				break;

mica-mqtt-client/src/main/java/net/dreamlu/iot/mqtt/core/client/MqttClient.java

@@ -45,6 +45,10 @@ import java.util.stream.Collectors;
  */
 public final class MqttClient {
 	private static final Logger logger = LoggerFactory.getLogger(MqttClient.class);
+	/**
+	 * 是否需要重新订阅
+	 */
+	private static final String MQTT_NEED_RE_SUB = "MQTT_NEED_RE_SUB";
 	private final TioClient tioClient;
 	private final MqttClientCreator config;
 	private final TioClientConfig clientTioConfig;
@@ -447,6 +451,56 @@ public final class MqttClient {
 		}
 	}
 
+
+	/**
+	 * 重连到新的服务端节点
+	 *
+	 * @param ip   ip
+	 * @param port port
+	 * @return 是否成功
+	 */
+	public boolean reconnect(String ip, int port) {
+		return reconnect(new Node(ip, port));
+	}
+
+	/**
+	 * 重连到新的服务端节点
+	 *
+	 * @param serverNode Node
+	 * @return 是否成功
+	 */
+	public boolean reconnect(Node serverNode) {
+		// 更新 ip 和端口
+		this.config.ip(serverNode.getIp()).port(serverNode.getPort());
+		// 获取老的
+		ClientChannelContext oldContext = getContext();
+		if (oldContext != null) {
+			Tio.remove(context, "切换服务地址：" + serverNode);
+		}
+		try {
+			this.context = tioClient.connect(serverNode, config.getTimeout());
+			this.context.set(MQTT_NEED_RE_SUB, (byte) 1);
+			return true;
+		} catch (Exception e) {
+			logger.error("mqtt client reconnect error", e);
+		}
+		return false;
+	}
+
+	/**
+	 * 是否需要重新订阅
+	 *
+	 * @param context ChannelContext
+	 * @return 是否需要重新订阅
+	 */
+	public static boolean isNeedReSub(ChannelContext context) {
+		if (context.containsKey(MQTT_NEED_RE_SUB)) {
+			context.remove(MQTT_NEED_RE_SUB);
+			return true;
+		}
+		return false;
+	}
+
 	/**
 	 * 断开 mqtt 连接
 	 *

starter/mica-mqtt-client-spring-boot-starter/src/main/java/net/dreamlu/iot/mqtt/spring/client/MqttClientTemplate.java

@@ -235,6 +235,17 @@ public class MqttClientTemplate implements SmartInitializingSingleton, Disposabl
 		client.reconnect();
 	}
 
+	/**
+	 * 重连到新的服务端节点
+	 *
+	 * @param ip   ip
+	 * @param port port
+	 * @return 是否成功
+	 */
+	public boolean reconnect(String ip, int port) {
+		return client.reconnect(ip, port);
+	}
+
 	/**
 	 * 断开 mqtt 连接
 	 *