重连时，主题重新订阅

Infrastructure/CloudSdk/mqtt/MqttClientManager.cs

@@ -7,6 +7,7 @@ using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
 using MQTTnet;
 using MQTTnet.Client;
+using MQTTnet.Packets;
 using MQTTnet.Protocol;
 
 namespace OpenAuth.WebApi;
@@ -26,6 +27,7 @@ public class MqttClientManager
     // 指数退避参数
     private readonly TimeSpan _minReconnectInterval = TimeSpan.FromSeconds(1);
     private readonly TimeSpan _maxReconnectInterval = TimeSpan.FromMinutes(2);
+    private List<String> _topics = new();
 
 
     public MqttClientManager(ILogger<MqttClientManager> logger)
@@ -86,8 +88,21 @@ public class MqttClientManager
     {
         _logger?.LogInformation("MQTT 连接成功");
         _inboundReconnectAttempts = 0; // 重置重连计数
-        // todo  重新订阅主题
-        return null;
+        // 重新订阅主题
+        return ResubscribeTopicsAsync();
+    }
+
+    private async Task ResubscribeTopicsAsync()
+    {
+        if (!_inBoundClient.IsConnected || _topics.Count == 0)
+            return;
+
+        _logger?.LogInformation($"重新订阅 {_topics.Count} 个主题");
+        foreach (var topic in _topics)
+        {
+            await _inBoundClient.SubscribeAsync(topic, MqttQualityOfServiceLevel.AtLeastOnce,
+                _cancellationTokenSource.Token);
+        }
     }
 
     private async Task OnOutboundDisconnectedAsync(MqttClientDisconnectedEventArgs e)
@@ -179,6 +194,7 @@ public class MqttClientManager
     public async Task SubscribeAsync(string topic,
         Func<MqttApplicationMessageReceivedEventArgs, Task> handler)
     {
+        _topics.Add(topic);
         await _inBoundClient.SubscribeAsync(topic, MqttQualityOfServiceLevel.AtMostOnce, CancellationToken.None);
         _inBoundClient.ApplicationMessageReceivedAsync += handler;
     }
@@ -188,6 +204,7 @@ public class MqttClientManager
     {
         foreach (var topic in topics)
         {
+            _topics.Add(topic);
             await _inBoundClient.SubscribeAsync(topic, MqttQualityOfServiceLevel.AtMostOnce, CancellationToken.None);
             _inBoundClient.ApplicationMessageReceivedAsync += handler;
         }