Netty（一）之helloworld

原创

CBeann 2022-09-13 11:45:08 博主文章分类：【Netty】 ©著作权

文章标签 Netty .net bootstrap 客户端 文章分类 后端开发

©著作权归作者所有：来自51CTO博客作者CBeann的原创作品，请联系作者获取转载授权，否则将追究法律责任

HelloWorld

客户端通向服务器端发送消息，服务器端读取数据（你好）并且返回（new Date()），客户端读取数据

pom

   <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>5.0.0.Alpha1</version>
        </dependency>

TimeServerHandler

服务器端读取数据并且回应请求，继承ChannelHandlerAdapter并且实现channelRead和exceptionCaught方法

package myhelloworld;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

import java.util.Date;

/**
 * @author CBeann
 * @create 2019-08-27 18:31
 */
public class TimeServerHandler extends ChannelHandlerAdapter {

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        //服务器读客户端发送来的数据
        ByteBuf buf = (ByteBuf) msg;
        byte[] req = new byte[buf.readableBytes()];
        buf.readBytes(req);
        String body = new String(req, "UTF-8");
        System.out.println("The TimeServer receive :" + body);

        //服务器向客户端回应请求
        ByteBuf response = Unpooled.copiedBuffer(new Date().toString().getBytes());
        ctx.writeAndFlush(response);

    }

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

//
}

TimeServer

package myhelloworld;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

/**
 * @author CBeann
 * @create 2019-08-27 18:22
 */
public class TimeServer {


    public static void main(String[] args) throws Exception {
        int port = 8080;
        //配置服务器端的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 ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeServerHandler());
                        }
                    });
            //绑定端口
            ChannelFuture f = b.bind(port).sync();
            //等待服务端监听端口关闭
            f.channel().closeFuture().sync();


        } catch (Exception e) {

        } finally {
            //优雅关闭，释放线程池资源
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

启动NettyServer的模版代码

private void bing(int port) {
    EventLoopGroup parentGroup = new NioEventLoopGroup(); 
    EventLoopGroup childGroup = new NioEventLoopGroup();
    try {
        ServerBootstrap b = new ServerBootstrap();
        b.group(parentGroup, childGroup)
                .channel(NioServerSocketChannel.class)    //非阻塞模式
                .option(ChannelOption.SO_BACKLOG, 128)
                .childHandler(new MyChannelInitializer());
        ChannelFuture f = b.bind(port).sync();
        System.out.println("itstack-demo-netty server start done. {关注公众号：bugstack虫洞栈，获取源码}");
        f.channel().closeFuture().sync();
    } catch (InterruptedException e) {
        e.printStackTrace();
    } finally {
        childGroup.shutdownGracefully();
        parentGroup.shutdownGracefully();
    }
}

TimeClientHandler

客户端读取服务器响应数据，继承ChannelHandlerAdapter并且实现channelRead和exceptionCaught方法

package myhelloworld;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;

/**
 * @author CBeann
 * @create 2019-08-27 18:47
 */
public class TimeClientHandler extends ChannelHandlerAdapter {


    //客户端读取服务器发送的数据
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        try {
            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);
        } catch (Exception e) {

        } finally {
            //标配
            ReferenceCountUtil.release(msg);
        }


    }

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

TimeClient

package myhelloworld;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

/**
 * @author CBeann
 * @create 2019-08-27 18:43
 */
public class TimeClient {


    public static void main(String[] args) throws Exception {
        int port = 8080;
        String host = "127.0.0.1";
        //配置客户端NIO线程组
        EventLoopGroup group = new NioEventLoopGroup();
        try {
            Bootstrap b = new Bootstrap();
            b.group(group)
                    .channel(NioSocketChannel.class)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            //TimeClientHandler是自己定义的方法
                            socketChannel.pipeline().addLast(new TimeClientHandler());
                        }
                    });
            //发起异步连接操作
            ChannelFuture f = b.connect(host, port).sync();


            //发送数据
            f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);//防止TCP粘包
            //f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);
            //f.channel().writeAndFlush(Unpooled.copiedBuffer("您好".getBytes()));
            //Thread.sleep(1000);


            //等待客户端链路关闭
            f.channel().closeFuture().sync();

        } catch (Exception e) {

        } finally {
            //优雅关闭
            group.shutdownGracefully();
        }
    }
}