荣耀设备（如荣耀10 Lite）Java客户端无法连接SignalR求助

Hey there, sorry to hear your SignalR-powered chat app is failing to connect on Honor 10 Lite and similar Honor devices—let’s walk through the most common fixes to resolve this issue:

• Update the System WebView
  Honor 10 Lite runs Android 9, which might come with an outdated default WebView. SignalR relies on modern web APIs like WebSocket or Server-Sent Events (SSE), and old WebView versions often lack proper support for these.
  To fix this:

  1. Go to Settings > Apps > Android System WebView on the device.
  2. Tap "Check for updates" and install any available updates.
  3. If updates are unavailable, install the Chrome browser—Chrome replaces the system WebView on most Android devices and gets more frequent updates.

• Force Compatible Transport Protocols
  Some older devices struggle with WebSocket connections, and SignalR’s automatic fallback might not always work as expected. Manually specify more compatible transport types in your client code:

  .NET Client Example: #

  var connection = new HubConnectionBuilder()
      .WithUrl("your-hub-endpoint-url", options =>
      {
          // Skip WebSocket, use SSE and Long Polling instead
          options.Transports = HttpTransportType.ServerSentEvents | HttpTransportType.LongPolling;
      })
      .Build();
  

  JavaScript Client Example: #

  const connection = new signalR.HubConnectionBuilder()
      .withUrl("/chatHub", {
          transport: signalR.HttpTransportType.ServerSentEvents | signalR.HttpTransportType.LongPolling
      })
      .build();
  

• Check Device Network & Battery Restrictions
  Honor devices have strict system-level controls that can block long-lived SignalR connections:

  • Ensure your app has the INTERNET permission (add <uses-permission android:name="android.permission.INTERNET" /> to your AndroidManifest.xml if missing).
  • Disable any active VPN or proxy settings—these can intercept SignalR traffic.
  • Add your app to the battery optimization whitelist: Go to Settings > Battery > App Launch Management, find your app, disable "Auto Manage" and enable "Allow background activity".

• Verify SSL/TLS Compatibility
  If your SignalR server uses HTTPS:

  • Older Android 9 devices might not support TLS 1.3. Temporarily enable TLS 1.0/1.1 on your server to test compatibility (you can re-enable stricter protocols later if this fixes the issue).
  • Avoid self-signed certificates—Honor’s system might block connections to untrusted endpoints. Use a certificate from a trusted root CA instead.

• Enable Detailed Logging for Debugging
  Add verbose logging to your client to pinpoint the exact failure reason:

  .NET Client Logging: #

  connection.LogLevel = LogLevel.Trace;
  connection.Closed += async (error) =>
  {
      Console.WriteLine($"Connection failed: {error?.Message ?? "Unknown error"}");
      // Optional: Auto-reconnect logic
      await Task.Delay(2000);
      await connection.StartAsync();
  };
  

  JavaScript Client Logging: #

  signalR.LogLevel = signalR.LogLevel.Trace;
  connection.onclose(error => {
      console.error(`Connection closed unexpectedly: ${error.message}`);
  });
  

  Check the logs for errors like connection timeouts, protocol mismatches, or certificate validation failures.

• Downgrade SignalR Client Version (If Needed)
  If you’re using the latest SignalR client (e.g., 8.x), it might have dropped support for older Android versions like 9. Try downgrading to a compatible version (e.g., Microsoft.AspNetCore.SignalR.Client 6.x) and test again.

内容的提问来源于stack exchange，提问作者reyhane