02_Netty实现的Echo服务器和客户端

public class EchoServer { ???private final int port; ???public EchoServer(int port) { ???????this.port = port; ???} ???public static void main(String[] args) throws Exception { ???????new EchoServer(9999).start(); ???} ???public void start() throws Exception { ???????NioEventLoopGroup group = new NioEventLoopGroup(); ???????try { ???????????ServerBootstrap b = new ServerBootstrap(); ??//创建ServerBootstrap ???????????b.group(group) ???????????????????.channel(NioServerSocketChannel.class) ??//指定NIO的传输Channel ???????????????????.localAddress(new InetSocketAddress(port)) ???????????????????.childHandler(new ChannelInitializer<SocketChannel>() { ???????????????????????@Override ???????????????????????protected void initChannel(SocketChannel channel) throws Exception { ???????????????????????????channel.pipeline().addLast(new EchoServerHandler()); ?//添加EchoServerHandler到Channel的ChannelPipeline ???????????????????????} ???????????????????}); ???????????ChannelFuture future = b.bind().sync(); ?//绑定服务器，sync等待服务器关闭 ???????????System.out.println(EchoServer.class.getName() + " started and listen on " + future.channel().localAddress()); ???????????future.channel().closeFuture().sync(); ???????} finally { ???????????group.shutdownGracefully().sync(); ???????} ???}}

public class EchoServerHandler extends ChannelInboundHandlerAdapter { ???@Override ???public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { ???????ByteBuf ?in = (ByteBuf)msg; ???????System.out.println("Server received:"+in.toString(CharsetUtil.UTF_8)); ???????ctx.write(in); ???} ???@Override ???public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ???????ctx.writeAndFlush(Unpooled.EMPTY_BUFFER) ???????????????.addListener(ChannelFutureListener.CLOSE); ???} ???@Override ???public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ???????cause.printStackTrace(); ???????ctx.close(); ???} ???@Override ???public void channelActive(ChannelHandlerContext ctx) throws Exception { ???????System.out.println("Server is Active......"); ???}}

ChannelInboundHandler的实现方法作用channelRead() ????????//每次收到信息都会回调channelReadComplete() //channelRead执行结束时回调exceptionCaught() ????//执行异常情况下会被回调。

public class EchoClient { ???private final String host; ???private final int port; ???public EchoClient(String host, int port) { ???????this.host = host; ???????this.port = port; ???} ???public static void main(String[] args) throws Exception{ ???????new EchoClient("127.0.0.1",9999).start(); ???} ???public void start() throws Exception{ ???????EventLoopGroup group = new NioEventLoopGroup(); ???????try{ ???????????Bootstrap b = new Bootstrap(); ???????????b.group(group) ???????????????????.channel(NioSocketChannel.class) ???????????????????.remoteAddress(new InetSocketAddress(host,port)) ???????????????????.handler(new ChannelInitializer<SocketChannel>() { ???????????????????????@Override ???????????????????????protected void initChannel(SocketChannel channel) throws Exception { ???????????????????????????channel.pipeline().addLast( ???????????????????????????????????new EchoClientHandler() ???????????????????????????); ???????????????????????} ???????????????????}); ???????????ChannelFuture future = b.connect().sync(); ???????????future.channel().closeFuture().sync(); ???????}finally { ???????????group.shutdownGracefully(); ???????} ???}}

public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> { ???@Override ???public void channelActive(ChannelHandlerContext ctx) throws Exception { ???????System.out.println("client is active......"); ???????ctx.writeAndFlush(Unpooled.copiedBuffer("Netty rocks!", CharsetUtil.UTF_8)); ???} ???@Override ???protected void channelRead0(ChannelHandlerContext channelHandlerContext, ByteBuf in) throws Exception { ???????System.out.println("client received:"+ in.toString(CharsetUtil.UTF_8)); ???} ???@Override ???public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ???????cause.printStackTrace(); ???????ctx.close(); ???}}