netty simple demo

package com.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class NettyServer {
	private static final String IP = "127.0.0.1";
	private static final int PORT = 9991;
	/** 用于分配处理业务线程的线程组个数 */
	protected static final int BIZGROUPSIZE = Runtime.getRuntime().availableProcessors() * 2; // 默认
	/** 业务出现线程大小 */
	protected static final int BIZTHREADSIZE = 4;
	/*
	 * NioEventLoopGroup实际上就是个线程池,
	 * NioEventLoopGroup在后台启动了n个NioEventLoop来处理Channel事件,
	 * 每一个NioEventLoop负责处理m个Channel,
	 * NioEventLoopGroup从NioEventLoop数组里挨个取出NioEventLoop来处理Channel
	 */
	private static final EventLoopGroup bossGroup = new NioEventLoopGroup(BIZGROUPSIZE);
	private static final EventLoopGroup workerGroup = new NioEventLoopGroup(BIZTHREADSIZE);

	protected static void start() throws Exception {
		try {
			ServerBootstrap b = new ServerBootstrap();
			b.group(bossGroup, workerGroup);
			b.channel(NioServerSocketChannel.class);
			b.childHandler(new ChannelInitializer<SocketChannel>() {
				@Override
				public void initChannel(SocketChannel ch) throws Exception {
					ChannelPipeline pipeline = ch.pipeline();
					pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
					pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
					pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
					pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));
					pipeline.addLast(new TcpServerHandler());
				}
			});

			ChannelFuture channelFuture = b.bind(IP, PORT).sync();
			channelFuture.channel().closeFuture().sync();
			System.out.println("server is started");
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			workerGroup.shutdownGracefully().sync();
			bossGroup.shutdownGracefully().sync();
		}

	}

	public static void main(String[] args) throws Exception {
		start();
	}

	private static class TcpServerHandler extends SimpleChannelInboundHandler<Object> {

		@Override
		protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
			System.out.println("SERVER receive msg:" + msg);
			if (msg != null && msg.toString().trim().length() > 0) {
				ctx.channel().writeAndFlush("server accepted " + msg);
			}
		}

		@Override
		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
			cause.printStackTrace();
			ctx.close();
		}
	}
}
package com.netty;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

public class TcpClient {
	public static String HOST = "127.0.0.1";
	public static int PORT = 9991;
	private static EventLoopGroup group = new NioEventLoopGroup();

	public static void main(String[] args) throws Exception {
		try {
			Bootstrap b = new Bootstrap();
			b.group(group).channel(NioSocketChannel.class);
			b.handler(new ChannelInitializer<Channel>() {
				@Override
				protected void initChannel(Channel ch) throws Exception {
					ChannelPipeline pipeline = ch.pipeline();
					pipeline.addLast("frameDecoder", new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
					pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
					pipeline.addLast("decoder", new StringDecoder(CharsetUtil.UTF_8));
					pipeline.addLast("encoder", new StringEncoder(CharsetUtil.UTF_8));
					pipeline.addLast("handler", new TcpServerHandler());
				}
			});
			b.option(ChannelOption.SO_KEEPALIVE, true);
			// 连接服务端
			ChannelFuture f = b.connect(HOST, PORT).sync();
			f.channel().closeFuture().sync();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static class TcpServerHandler extends SimpleChannelInboundHandler<Object> {
		@Override
		public void channelActive(ChannelHandlerContext ctx) throws Exception {
			ctx.writeAndFlush("hello");
		}

		@Override
		protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
			System.out.println("client receive msg:" + msg);
			if (msg != null && msg.toString().trim().length() > 0) {
				ctx.channel().writeAndFlush("client send " + msg);
			}

		}

		@Override
		public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
			System.out.println("Unexpected exception from downstream." + cause);
			ctx.close();
		}
	}
}