Simple Netty Tcp Server

原文链接

Channel Pipeline API to build chain of handlers

To perform read and write, Netty provides you Channel Handlers, inbound & outbound. When there is something to read, Channel Inbound Handlers are invoked and when there is something to write, Channel Outbound Handlers are invoked.

class SimpleNettyServerBootstrap {

    void start(int port) throws InterruptedException {
        Utils.log("Starting server at: " + port);
        EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
        EventLoopGroup workerGroup = new NioEventLoopGroup();// (2)
        try {
            ServerBootstrap b = new ServerBootstrap();// (3)
            b.group(bossGroup, workerGroup) // (4)
                    .channel(NioServerSocketChannel.class)// (5)
                    .childHandler(new SimpleTCPChannelInitializer())// (6)
                    .childOption(ChannelOption.SO_KEEPALIVE, true);// (7)

            // Bind and start to accept incoming connections.
            ChannelFuture f = b.bind(port).sync();// (8)
            if(f.isSuccess()) Utils.log("Server started successfully"); // (9)
            f.channel().closeFuture().sync(); // (10)
        } finally {
            Utils.log("Stopping server");
            workerGroup.shutdownGracefully();// (11)
            bossGroup.shutdownGracefully();// (12)
        }
    }
}

public class SimpleTCPChannelHandler extends SimpleChannelInboundHandler<String> {
​
 @Override
 public void channelActive(ChannelHandlerContext ctx) {
   Utils.log(ctx.channel().remoteAddress(), "Channel Active");
 }
​
 @Override
 protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
   Utils.log(ctx.channel().remoteAddress(), s);// (1)
   ctx.channel().writeAndFlush("Thanks\n"); // (2)
 }
​
 @Override
 public void channelInactive(ChannelHandlerContext ctx) {
   Utils.log(ctx.channel().remoteAddress(), "Channel Inactive");
 }
}

Tcp非全双工的，You can’t directly send or receive objects over TCP channel. You have to convert from bytes to object while reading and from objects to bytes while writing?