Netty学习笔记(二) 实现服务端和客户端

喜欢ヅ旅行 2022-01-05 13:09 421阅读 0赞

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.Sharable public class EchoServiceHandle extends SimpleChannelInboundHandler<String> { /** * 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 */ @Data public 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<SocketChannel>() { @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.Sharable public class EchoClientHandle extends SimpleChannelInboundHandler<String> { /** * 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) @Slf4j public 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<SocketChannel>() { @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 ###

channelActive
    channelRead = Send ----> 客户端c0d4f037你好，我已经接收到你发送的消息

转载于:https://www.cnblogs.com/zhoutao825638/p/10382157.html