在 Android 中的 Java Websocket 服務器收到消息時，不會創建 Toast 消息

Question

我正在嘗試使用此庫創建基本的 WebSocket 服務器。 我想在收到消息時制作一條吐司消息。 在下面的 onMessage() 函數中，我已經實現了。 但是沒有發生吐司消息。

但是 Received 消息打印在控制台上。

        WebSocketServer ws = new WebSocketServer(new InetSocketAddress(3000)) {

        @Override
        public void onOpen(WebSocket conn, ClientHandshake handshake) {
            conn.send("Hello world");
        }

        @Override
        public void onClose(WebSocket conn, int code, String reason, boolean remote) {

        }

        @Override
        public void onMessage(WebSocket conn, String message) {
            System.out.println("Recieved: "+message);
            Toast.makeText(MainActivity.this, "Recieved: " + message, Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onError(WebSocket conn, Exception ex) {

        }

        @Override
        public void onStart() {

        }
    };
    ws.start();
}

Answer 1

我認為您必須切換到 UI 線程才能顯示 Toast。

您可以嘗試使用Handler ：

new Handler(Looper.getMainLooper()).post(new Runnable() {
    public void run() {
        Toast.makeText(MainActivity.this, "Received: " + message, Toast.LENGTH_SHORT).show();
    }
});

或調用runOnUiThread ：

runOnUiThread(new Runnable() {
    @Override
    public void run() {
        Toast.makeText(MainActivity.this, "Received: " + message, Toast.LENGTH_SHORT).show();
    }
});

或廣播消息：

@Override
public void onMessage(WebSocket conn, String message) {
    System.out.println("Recieved: "+message);

    Intent intent = new Intent("msgReceived");
    intent.putExtra("message", message);
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

並在您的活動中注冊一個 BroadcastReceiver：

private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String message = intent.getExtras().getString("message");
        Toast.makeText(MainActivity.this, "Received: " + message, Toast.LENGTH_SHORT).show();
    }
};

@Override
protected void onStart() {
    super.onStart();
    LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver, new IntentFilter("msgReceived"));

@Override
protected void onStop() {
    LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
    super.onStop();
}