用netty动态传输数据

Question

I've been learning Netty for a while, and from the Netty's tutorials(the MEAP book), almostly the examples are based on a fixed framework, like the EventLoop , Bootstrap , it seems that only the implementations of the handlers in the channelPipeline are the things we really should be concerned about.

Here I wanna design a simple chess game, based on a Server/Client mode, where two players are on different computers. And the background data I want to use Netty to transmit.(I just wanna practice using netty)

And in such a game, the front GUI detect the player put a chessman and then make some change to the data. Then, I need to deliver this data to the other player. And here comes the question.

I don't know how to implement a ChannelHandler in this situation, because in most examples, it seems that the data are not added dynamically by the handler. For instance, the data was created when channel was active by the method channelActive() or something else. All these methods was auto-invoked by Netty itself.

The only method I think is the write() . However, it seems that I have to call this method by myself if I implements this method, I don't know where I can get the parameter ChannelHandlerContext .

So, how to solve problems like this?

---

ps I'm not so familiar with java network programming, nor the Netty. All the things I learn is based on the book, which I haven't finished reading yet. :)

Answer 1

Channel hander of Netty looks

package netty_sample;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelHandler;

/**
 * Server side action
 */
public class EchoServerHandler extends SimpleChannelHandler {
    /**
     * This method will be invoked when server recieved a message
    */
    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent event) {
        String msg = (String) event.getMessage(); // extract a message received

        // You can write any code which handles the message, changes data, and create message for client, etc. 

        ctx.getChannel().write(someMessageToClient); // send back to client
    }
}

As I understand, handler routine is invoked dynamically (in event-driven) when server received a message. So code in the handler works dynamically, and you can write anything in the code.