feat: 目标不在线时进行提示和更新UI

WebRTCController/app/src/main/java/com/ttstd/controller/MainActivity.java

@@ -269,9 +269,27 @@ public class MainActivity extends AppCompatActivity {
             case "ICE_CANDIDATE":
                 handleIceCandidate(message);
                 break;
+            case "TARGET_OFFLINE":
+                handleTargetOffline(message);
+                break;
         }
     }
 
+    private void handleTargetOffline(SignalMessage message) {
+        String offlineId = message.getToDeviceId();
+        String payload = message.getPayload();
+        String text = (payload != null && !payload.isEmpty())
+                ? payload
+                : "目标被控端不在线，请确认设备已开启并连接服务器";
+        String finalText = text;
+        runOnUiThread(() -> {
+            tvStatus.setText("状态: " + finalText);
+            Toast.makeText(MainActivity.this, finalText, Toast.LENGTH_LONG).show();
+            updateUI(false);
+        });
+        Log.w(TAG, "Target device " + offlineId + " is offline");
+    }
+
     private void handleAnswer(SignalMessage message) {
         try {
             JsonObject payload = gson.fromJson(message.getPayload(), JsonObject.class);

WebRTCSignalServer/src/main/java/com/ttstd/signaling/handler/SignalWebSocketHandler.java

@@ -57,13 +57,17 @@ public class SignalWebSocketHandler extends TextWebSocketHandler {
                     break;
                 case "OFFER":
                 case "ANSWER":
+                    // 关键信令：目标不在线时回送 TARGET_OFFLINE 提醒发送方
+                    forwardMessage(signalMessage, true);
+                    break;
                 case "ICE_CANDIDATE":
                 case "CONTROL_COMMAND":
-                    forwardMessage(signalMessage);
+                    // 普通信令：目标不在线时静默丢弃，不返回提示
+                    forwardMessage(signalMessage, false);
                     break;
                 default:
-                    // 其他消息类型直接转发
+                    // 其他消息类型直接转发，目标不在线时静默丢弃
-                    forwardMessage(signalMessage);
+                    forwardMessage(signalMessage, false);
                     break;
             }
         } catch (Exception e) {
@@ -122,7 +126,7 @@ public class SignalWebSocketHandler extends TextWebSocketHandler {
         sendToSession(session, response);
     }
 
-    private void forwardMessage(SignalMessage message) {
+    private void forwardMessage(SignalMessage message, boolean notifyOffline) {
         String toDeviceId = message.getToDeviceId();
         if (toDeviceId == null) {
             logger.warn("Cannot forward message: toDeviceId is null");
@@ -132,6 +136,10 @@ public class SignalWebSocketHandler extends TextWebSocketHandler {
         WebSocketSession targetSession = sessionManager.getSession(toDeviceId);
         if (targetSession == null || !targetSession.isOpen()) {
             logger.warn("Target device {} is not online", toDeviceId);
+            // 仅 OFFER / ANSWER 在目标不在线时回送 TARGET_OFFLINE，其余类型静默丢弃
+            if (notifyOffline) {
+                notifySenderTargetOffline(message, toDeviceId);
+            }
             return;
         }
 
@@ -144,6 +152,31 @@ public class SignalWebSocketHandler extends TextWebSocketHandler {
         }
     }
 
+    /**
+     * 目标被控端不在线时，向发送方（主控端）回送 TARGET_OFFLINE 提醒。
+     */
+    private void notifySenderTargetOffline(SignalMessage message, String offlineDeviceId) {
+        String fromDeviceId = message.getFromDeviceId();
+        if (fromDeviceId == null) {
+            logger.warn("Cannot notify offline state: fromDeviceId is null");
+            return;
+        }
+
+        WebSocketSession senderSession = sessionManager.getSession(fromDeviceId);
+        if (senderSession == null || !senderSession.isOpen()) {
+            logger.warn("Sender {} session not found, cannot notify target offline", fromDeviceId);
+            return;
+        }
+
+        Map<String, Object> response = new HashMap<>();
+        response.put("type", "TARGET_OFFLINE");
+        response.put("toDeviceId", offlineDeviceId);
+        response.put("payload", "目标被控端（" + offlineDeviceId + "）不在线，请确认设备已开启并连接到信令服务器");
+
+        sendToSession(senderSession, response);
+        logger.info("Notified sender {} that target {} is offline", fromDeviceId, offlineDeviceId);
+    }
+
     private void sendToSession(WebSocketSession session, Object data) {
         try {
             String json = objectMapper.writeValueAsString(data);

webrtc_controller_flutter/lib/controller/remote_controller.dart

@@ -30,6 +30,9 @@ class RemoteController {
   /// ICE 连接断开（用于提示用户并返回连接设置）。
   void Function(String message)? onIceDisconnected;
 
+  /// 目标被控端不在线（服务器回送 TARGET_OFFLINE，用于提示用户并复位 UI）。
+  void Function(String message)? onTargetOffline;
+
   /// 远端视频渲染器就绪。
   void Function(RTCVideoRenderer renderer)? onRemoteStream;
 
@@ -92,6 +95,11 @@ class RemoteController {
         final payload = jsonDecode(message.payload!) as Map<String, dynamic>;
         _webRtc?.handleIceCandidate(payload);
         break;
+      case 'TARGET_OFFLINE':
+        final text = message.payload ?? '目标被控端不在线，请确认设备已开启并连接服务器';
+        onStatusChanged?.call('状态: $text');
+        onTargetOffline?.call(text);
+        break;
     }
   }
 

webrtc_controller_flutter/lib/main.dart

@@ -99,6 +99,9 @@ class _ControllerHomeState extends State<ControllerHome> {
     _controller!.onIceDisconnected = (message) {
       _onIceDisconnected(message);
     };
+    _controller!.onTargetOffline = (message) {
+      _onTargetOffline(message);
+    };
     _controller!.onRemoteStream = (renderer) {
       setState(() => _renderer = renderer);
       renderer.addListener(_onRendererUpdate);
@@ -130,6 +133,20 @@ class _ControllerHomeState extends State<ControllerHome> {
     await _disconnect();
   }
 
+  /// 目标被控端不在线：提示用户并复位到连接设置面板。
+  Future<void> _onTargetOffline(String message) async {
+    final scaffoldCtx = _scaffoldKey.currentState?.context;
+    if (mounted && scaffoldCtx != null) {
+      ScaffoldMessenger.of(scaffoldCtx).showSnackBar(
+        SnackBar(
+          content: Text(message),
+          duration: const Duration(seconds: 3),
+        ),
+      );
+    }
+    setState(() => _connected = false);
+  }
+
   Future<void> _disconnect() async {
     await _controller?.disconnect();
     _controller = null;