在Netty学习笔记(一) 实现DISCARD服务中，我们使用Netty和Python实现了简单的丢弃DISCARD服务，这篇，我们使用Netty实现服务端和客户端交互的需求。
前置工作
开发环境
- JDK8
- Netty版本:5.0.0.Alpha2
- 集成环境:IDEA
- 构建工具：Gradle
依赖
compile group: 'io.netty', name: 'netty-all', version: '5.0.0.Alpha2' compile group: 'org.projectlombok', name: 'lombok', version: '1.18.0'
服务端
Netty服务器主要由两部分组成:
- 配置服务器功能，如线程、端口
- 实现服务器处理程序
服务端HandleAdapter
我们是首先实现服务端处理程序，实现Handle要求继承HandleAdapter,这里我们继承SimpleChannelInboundHandler<T>,下面是具体实现的代码信息,其每个函数的作用，我们只需要重写我们所需要的方法即可。
import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.SimpleChannelInboundHandler;/** * Netty 服务Handle * * @author tao */@ChannelHandler.Sharablepublic class EchoServiceHandle extends SimpleChannelInboundHandler{ /** * 接收到新的消息 * @param ctx * @param msg * @throws Exception */ @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { // 打印接收到的消息 System.out.println("Netty服务端接收到消息 " + msg); // 回复消息 ctx.channel().writeAndFlush("Send ----> 客户端" + ctx.channel().id() + "你好，我已经接收到你发送的消息"); } /** * 有新的连接加入 * @param ctx * @throws Exception */ @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { System.out.println("接入新的Channel,id = " + ctx.channel().id()); } /** * 服务端发生异常信息的时候 * @param ctx * @param cause */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // 服务端发生异常 System.out.println("Netty 服务端发生异常 ,异常信息：" + cause); ctx.close(); } @Override protected void messageReceived(ChannelHandlerContext ctx, String msg) {}}
服务端启动
在服务端的EchoServiceHandle完成之后，我们需要配置服务器的参数信息，比如端口等
import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.*;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.handler.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;import lombok.Data;/** * @author tao */@Datapublic class EchoService { private int port; public void start() throws Exception { EventLoopGroup boosGroup = new NioEventLoopGroup(); EventLoopGroup workGroup = new NioEventLoopGroup(); try { ServerBootstrap bootstrap = new ServerBootstrap(); bootstrap .group(boosGroup, workGroup) .channel(NioServerSocketChannel.class) .option(ChannelOption.SO_BACKLOG, 128) .childHandler( new ChannelInitializer () { @Override protected void initChannel(SocketChannel ch) throws Exception { ChannelPipeline pipeline = ch.pipeline(); //字符串解码器 pipeline.addLast(new StringDecoder()); //字符串编码器 pipeline.addLast(new StringEncoder()); //服务端处理器 pipeline.addLast(new EchoServiceHandle()); } }); ChannelFuture sync = bootstrap.bind(port).sync(); System.out.println("Netty Service start with " + port + "..."); sync.channel().closeFuture().sync(); } finally { workGroup.shutdownGracefully(); boosGroup.shutdownGracefully(); } } public static void main(String[] args) throws Exception { EchoService service = new EchoService(); service.setPort(8080); service.start(); }} 启动后，我们可以看到启动信息如下:
Netty Service start with 8080...
客户端
客户端和服务端类似,可以相互参考学习.
客户端HandleAdapter
import io.netty.buffer.Unpooled;import io.netty.channel.ChannelHandler;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.SimpleChannelInboundHandler;import io.netty.util.CharsetUtil;@ChannelHandler.Sharablepublic class EchoClientHandle extends SimpleChannelInboundHandler{ /** * 连接创建成功的时候 * @param ctx * @throws Exception */ @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { System.out.println("channelActive"); //连接成功后向服务端发送问候消息 ctx.channel().writeAndFlush(Unpooled.copiedBuffer("你好，这里是Netty客户端", CharsetUtil.UTF_8)); } /** * 发生异常 * @param ctx * @param cause */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { System.out.println("exceptionCaught"); cause.printStackTrace(); ctx.close(); } /** * 接收到服务端发过来的数据 * @param ctx * @param msg */ @Override public void channelRead(ChannelHandlerContext ctx, Object msg) { //打印接收到的数据信息 System.out.println("channelRead = " + msg); } @Override protected void messageReceived(ChannelHandlerContext ctx, String msg) {}}
客户端启动
import io.netty.bootstrap.Bootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;import io.netty.handler.codec.string.StringDecoder;import io.netty.handler.codec.string.StringEncoder;import lombok.Data;import lombok.experimental.Accessors;import lombok.extern.slf4j.Slf4j;import java.net.InetSocketAddress;/** @author tao */@Data@Accessors(chain = true)@Slf4jpublic class EchoClient { private int port; private String host; public void start() throws Exception { EventLoopGroup group = new NioEventLoopGroup(); try { Bootstrap bootstrap = new Bootstrap(); bootstrap .group(group) .channel(NioSocketChannel.class) .handler( new ChannelInitializer () { @Override protected void initChannel(SocketChannel ch) throws Exception { ChannelPipeline pipeline = ch.pipeline(); // 字符串解码器 pipeline.addLast(new StringDecoder()); // 字符串编码器 pipeline.addLast(new StringEncoder()); pipeline.addLast(new EchoClientHandle()); } }); ChannelFuture sync = bootstrap.connect(new InetSocketAddress(host, port)).sync(); sync.channel().closeFuture().sync(); } catch (Exception e) { e.printStackTrace(); } finally { group.shutdownGracefully().sync(); } } public static void main(String[] args) throws Exception { EchoClient client = new EchoClient(); client.setHost("127.0.0.1").setPort(8080); client.start(); }} 效果
服务端效果
Netty Service start with 8080... 接入新的Channel,id = c0d4f037 Netty服务端接收到消息 你好，这里是Netty客户端
客户端效果
channelActivechannelRead = Send ----> 客户端c0d4f037你好，我已经接收到你发送的消息