Netty初体验

package netty_starter;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * @auther guozg
 */
public class DiscardServer {

    private int port;

    public DiscardServer(int port) {
        this.port = port;
    }

    public void run() throws InterruptedException {
        EventLoopGroup bossGroup = new NioEventLoopGroup(); // (1)
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap(); // (2)
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class) // (3)
                    .childHandler(new ChannelInitializer<SocketChannel>() { // (4)
                        @Override
                        public void initChannel(SocketChannel ch) throws Exception {
                            ch.pipeline().addLast(new DiscardServerHandler())
                            .addLast(new OpenHandler());
                        }
                    })
                    .option(ChannelOption.SO_BACKLOG, 128)          // (5)
                    .childOption(ChannelOption.SO_KEEPALIVE, true); // (6)

            // Bind and start to accept incoming connections.
            ChannelFuture f = b.bind(port).sync(); // (7)
            // Wait until the server socket is closed.
            // In this example, this does not happen, but you can do that to gracefully
            // shut down your server.
            f.channel().closeFuture().sync();
        } finally {
            workerGroup.shutdownGracefully();
            bossGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        int port;
        if (args.length > 0) {
            port = Integer.parseInt(args[0]);
        } else {
            port = 8088;
        }
        new DiscardServer(port).run();
    }
}

　　

package netty_starter;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
import io.netty.util.ReferenceCountUtil;
import study01.ChannelList;

/**
 * @auther guozg
 */
public class DiscardServerHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { // (2)
//        super.channelRead(ctx, msg);
//        ((ByteBuf) msg).release(); // (3)
        ByteBuf in = (ByteBuf) msg;
        String message = in.toString(CharsetUtil.UTF_8);
        System.out.println(message);
        sendMessage(Unpooled.copiedBuffer(message,CharsetUtil.UTF_8).retain(ChannelList.channels.size()-1),ctx.channel());
//        try {
//            while (in.isReadable()) {
//                char s = in.getChar(0);
//                System.out.print((char) in.readByte());
//                System.out.flush();
//            }
//        } finally {
//            ReferenceCountUtil.release(msg);
//        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { // (5)
//        super.exceptionCaught(ctx, cause);
        cause.printStackTrace();
        ctx.close();
    }

    public void sendMessage(Object msg,Channel channel){

        for (Channel c:ChannelList.channels){
            if(channel != c) {
                c.writeAndFlush(msg);
            }
        }

    }

}

　　

package netty_starter;

import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
import study01.ChannelList;

public class OpenHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ChannelList.channels.add(ctx.channel());
        sendMessage(Unpooled.copiedBuffer("New client in!\n",CharsetUtil.UTF_8).retain(ChannelList.channels.size()));//retain设置读取次数
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        ChannelList.channels.remove(ctx.channel());
        ctx.close();
        sendMessage(Unpooled.copiedBuffer("One client out!\n",CharsetUtil.UTF_8).retain(ChannelList.channels.size()));
    }

    public void sendMessage(Object msg){

        for (Channel c:ChannelList.channels){
            c.writeAndFlush(msg);
        }

    }
}

　　然后启动cmd,输入telnet 127.0.0.1 8088.即可链接服务，并有返回值。可同时启动多个Telnet，实现群发消息。