Netty IO向客户端发送消息

Question

how can I send a message from the Server to the Client using Netty? I know you can do it like

  for (Channel c : channels1) {
    c.writeAndFlush("TEXT \r\n");
  }

but it is only usable from inside the ChatServerHandler Class. Is there a method to send Messages to the Client or how can I make a method which I can call like for example

sendMessageToServer("MESSAGE");

void sendMessageToServer(String message) {
final ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
      for (Channel c : channels) {
        c.writeAndFlush("TEXT \r\n");
      }
}

? If I get the Channels like in ChatServerHandler using

final ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

I get a Channel size of 0.

Answer 1

final ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
This constructs a new ChannelGroup with nothing inside.

You should have a class extends SimpleChannelInboundHandler<?> .
The channelActive(ChannelHandlerContext chc) method is called when something is connected. Simply add Channel instance to your channels by channels.add(chc.channel());
You may have to make your ChannelGroup public so it can be acessed everywhere. Good luck.