2. Netty源码分析之使用篇
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前言:在阅读Netty源码前,我们先了解下Netty的基本使用方法。
一、服务端代码
public class TimeServer public static void main(String[] args) throws Exception int port = 8080; if (args != null && args.length > 0) try port = Integer.valueOf(args[0]); catch (NumberFormatException e) // 采用默认值 new TimeServer().bind(port); public void bind(int port) throws Exception // 配置服务端的NIO线程组 EventLoopGroup bossGroup = new NioEventLoopGroup(); EventLoopGroup workerGroup = new NioEventLoopGroup(); try ServerBootstrap b = new ServerBootstrap(); b.group(bossGroup, workerGroup).channel(NioserverSocketChannel.class).option(ChannelOption.SO_BACKLOG, 1024) .childHandler(new ChildChannelHandler()); // 绑定端口,同步等待成功 ChannelFuture f = b.bind(port).sync(); // 等待服务端监听端口关闭 f.channel().closeFuture().sync(); finally // 优雅退出,释放线程池资源 bossGroup.shutdownGracefully(); workerGroup.shutdownGracefully(); private class ChildChannelHandler extends ChannelInitializer<SocketChannel> @Override protected void initChannel(SocketChannel arg0) throws Exception arg0.pipeline().addLast(new TimeServerHandler()); public class TimeServerHandler extends ChannelHandlerAdapter @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception ByteBuf buf = (ByteBuf) msg; byte[] req = new byte[buf.readableBytes()]; buf.readBytes(req); String body = new String(req, "UTF-8"); System.out.println("The time server receive order : " + body); String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(System.currentTimeMillis()).toString() : "BAD ORDER";
// 创建UnpooledHeapByteBuf,同时设置对象的各个值(copy了一份byte数组放进buffer对象中) ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes()); ctx.write(resp); @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception ctx.flush(); @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) ctx.close();
二、客户端代码
public class TimeClient public static void main(String[] args) throws Exception int port = 8080; if (args != null && args.length > 0) try port = Integer.valueOf(args[0]); catch (NumberFormatException e) // 采用默认值 new TimeClient().connect(port, "127.0.0.1"); public void connect(int port, String host) throws Exception // 配置客户端NIO线程组 EventLoopGroup group = new NioEventLoopGroup(); try Bootstrap b = new Bootstrap(); b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true) .handler(new ChannelInitializer<SocketChannel>() @Override public void initChannel(SocketChannel ch) throws Exception ch.pipeline().addLast(new TimeClientHandler()); ); // 发起异步连接操作 ChannelFuture f = b.connect(host, port).sync(); // 当代客户端链路关闭 f.channel().closeFuture().sync(); finally // 优雅退出,释放NIO线程组 group.shutdownGracefully(); public class TimeClientHandler extends ChannelHandlerAdapter private static final Logger logger = Logger.getLogger(TimeClientHandler.class.getName()); private final ByteBuf firstMessage; /** * Creates a client-side handler. */ public TimeClientHandler() byte[] req = "QUERY TIME ORDER".getBytes(); firstMessage = Unpooled.buffer(req.length); firstMessage.writeBytes(req); /** * 当客户端连接上服务端时,会触发ChannelActive(..) */ @Override public void channelActive(ChannelHandlerContext ctx) ctx.writeAndFlush(firstMessage); @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception ByteBuf buf = (ByteBuf) msg; byte[] req = new byte[buf.readableBytes()]; buf.readBytes(req); String body = new String(req, "UTF-8"); System.out.println("Now is : " + body); @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) // 释放资源 logger.warning("Unexpected exception from downstream : " + cause.getMessage()); ctx.close();
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