Netty 学习笔记（1） ------ Hello World

服务端启动流程

package com.example.netty;

import com.example.netty.handler.HelloServerHandler;

import io.netty.bootstrap.ServerBootstrap;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.SocketChannel;

import io.netty.channel.socket.nio.NioServerSocketChannel;

public class HelloServer {

    public static void main(String[] args) {

        NioEventLoopGroup bossGroup = new NioEventLoopGroup();

        NioEventLoopGroup workerGroup = new NioEventLoopGroup();

        ServerBootstrap serverBootstrap = new ServerBootstrap();

		//1. 指定线程组

        serverBootstrap.group(bossGroup, workerGroup)

                .localAddress(8000)//2. 指定端口

                .channel(NioServerSocketChannel.class)//3. 指定IO模型

                .childHandler(new ChannelInitializer<SocketChannel>() {

                    @Override

                    protected void initChannel(SocketChannel socketChannel) throws Exception {

                        socketChannel.pipeline().addLast(new HelloServerHandler());

                    }

                });//4. 配置业务处理逻辑类

		//5. 绑定端口

        serverBootstrap.bind().addListener((future)->{

            if(future.isSuccess()){

                System.out.println("端口绑定成功");

            }else{

                System.out.println("端口绑定失败:"+future.cause());

            }

        });

    }

}

bossGroup和workerGroup可以看作是传统IO网络编程的两个线程组，bossGroup负责 accept 新的socket连接，workerGroup负责socket连接的读写。
ServerBootstrap是服务端引导类，负责.group(bossGroup, workerGroup)配置线程模型；.channel指定IO模型，NioServerSocketChannel.class是NIO模型，OioServerSocketChannel.class是传统IO模型；.childHandler配置业务逻辑处理。
.bind()绑定端口，该方法是异步执行，所以需要配置监听器。

服务端业务处理类

package com.example.netty.handler;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelInboundHandlerAdapter;

import io.netty.util.CharsetUtil;

public class HelloServerHandler extends ChannelInboundHandlerAdapter {

    @Override

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

        ByteBuf byteBuf = (ByteBuf) msg;

        System.out.println(byteBuf.toString(CharsetUtil.UTF_8));

        ctx.writeAndFlush(Unpooled.copiedBuffer("hello client".getBytes()));

    }

}

主要打印客户端发送的消息并返回Hello Client。

客户端启动流程

package com.example.netty;

import com.example.netty.handler.HelloClientHandler;

import io.netty.bootstrap.Bootstrap;

import io.netty.channel.ChannelInitializer;

import io.netty.channel.nio.NioEventLoopGroup;

import io.netty.channel.socket.SocketChannel;

import io.netty.channel.socket.nio.NioSocketChannel;

public class HelloClient {

    public static void main(String[] args) {

        NioEventLoopGroup workerGroup = new NioEventLoopGroup();

        Bootstrap bootstrap = new Bootstrap();

		//1. 配置线程组

        bootstrap.group(workerGroup)

                .channel(NioSocketChannel.class)//2. 指定IO模型

                .remoteAddress("127.0.0.1", 8000)//3. 指定连接ip和端口

                .handler(new ChannelInitializer<SocketChannel>() {

                    @Override

                    protected void initChannel(SocketChannel socketChannel) throws Exception {

                        socketChannel.pipeline().addLast(new HelloClientHandler());

                    }

                });//4. 配置业务处理逻辑

		//5. 连接

        bootstrap.connect().addListener(future -> {

            if(future.isSuccess()){

                System.out.println("连接成功");

            }else{

                System.out.println("连接失败:" + future.cause());

            }

        });

    }

}

客户端引导类为Bootstrap，而服务端为ServerBootstrap

业务处理逻辑类

package com.example.netty.handler;

import io.netty.buffer.ByteBuf;

import io.netty.buffer.Unpooled;

import io.netty.channel.ChannelHandlerContext;

import io.netty.channel.ChannelInboundHandlerAdapter;

import io.netty.util.CharsetUtil;

public class HelloClientHandler extends ChannelInboundHandlerAdapter {

    @Override

    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        ctx.writeAndFlush(Unpooled.copiedBuffer("hello server".getBytes()));

    }

    @Override

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

        ByteBuf byteBuf = (ByteBuf) msg;

        System.out.println("recieve from server:" + byteBuf.toString(CharsetUtil.UTF_8));

    }

}

主要在连接后向服务端发送Hello Server，并接受打印服务端返回消息。

巴特西

Netty 学习笔记（1） ------ Hello World

服务端启动流程

客户端启动流程

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