Netty系列(三)：NettyDemo

介绍
客户端与服务端双向通信
客户端

package com.guo.demo.client;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.util.Date;
import java.util.concurrent.TimeUnit;

public class NettyClient {
    private static final int MAX_RETRY = 5;
    private static final String HOST = "127.0.0.1";
    private static final int PORT = 8000;

    public static void main(String[] args) {
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();
        Bootstrap bootstrap = new Bootstrap();

        bootstrap
                .group(workerGroup)
                .channel(NioSocketChannel.class)
                .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 5000)
                .option(ChannelOption.SO_KEEPALIVE, true)
                .option(ChannelOption.TCP_NODELAY, true)
                .handler(new ChannelInitializer() {
                    @Override
                    protected void initChannel(SocketChannel socketChannel) throws Exception {
                        socketChannel.pipeline().addLast(new ClientHandler());
                    }
                });
        connect(bootstrap, HOST, PORT, MAX_RETRY);
    }
    private static void connect(Bootstrap bootstrap, String host, int port, int maxRetry) {
        bootstrap.connect(host,port).addListener(future -> {
            if (future.isSuccess()){
                System.out.println("连接成功!");
            }else if(maxRetry == 0){
                System.err.println("重试次数已用完，放弃连接！");
            }else{
                // 第几次重连
                int order = (MAX_RETRY - maxRetry) + 1;
                // 本次重连的间隔
                int delay = 1 << order;
                System.err.println(new Date() + ": 连接失败，第" + order + "次重连……");
                bootstrap.config().group().schedule(() ->connect(bootstrap, host, port, maxRetry - 1),delay,
                        TimeUnit.SECONDS);
            }
        });
    }
}

ClientHandler

package com.guo.demo.client;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.nio.charset.Charset;
import java.util.Date;

public class ClientHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelActive(ChannelHandlerContext ctx){
        System.out.println(new Date() + ": 客户端写出数据");
        // 1.获取数据
        ByteBuf buffer = getByteBuf(ctx);

        // 2.写数据
        ctx.channel().writeAndFlush(buffer);
    }

    private ByteBuf getByteBuf(ChannelHandlerContext ctx) {
        byte[] bytes = "你好，西部落酋长!".getBytes(Charset.forName("utf-8"));

        ByteBuf buffer = ctx.alloc().buffer();

        buffer.writeBytes(bytes);

        return buffer;
    }
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;

        System.out.println(new Date() + ": 客户端读到数据 -> " + byteBuf.toString(Charset.forName("utf-8")));
    }
}

服务端

package com.guo.demo.server;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

public class NettyServer {
    private static final int PORT = 8000;

    public static void main(String[] args) {
        NioEventLoopGroup boosGroup = new NioEventLoopGroup();
        NioEventLoopGroup workerGroup = new NioEventLoopGroup();

        final ServerBootstrap serverBootstrap = new ServerBootstrap();
        serverBootstrap
                .group(boosGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .option(ChannelOption.SO_BACKLOG, 1024)
                .childOption(ChannelOption.SO_KEEPALIVE, true)
                .childOption(ChannelOption.TCP_NODELAY, true)
                .childHandler(new ChannelInitializer() {
                    protected void initChannel(NioSocketChannel ch) {
                        ch.pipeline().addLast(new ServerHandler());
                    }
                });
        bind(serverBootstrap, PORT);
    }

    private static void bind(ServerBootstrap serverBootstrap, int port) {
        serverBootstrap.bind(port).addListener(future -> {
            if (future.isSuccess()) {
                System.out.println("端口[" + port + "]绑定成功!");
            } else {
                System.err.println("端口[" + port + "]绑定失败!");
            }
        });
    }
}

ServerHandler

package com.guo.demo.server;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.nio.charset.Charset;
import java.util.Date;

public class ServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf byteBuf = (ByteBuf) msg;

        System.out.println(new Date() + ": 服务端读到数据 -> " + byteBuf.toString(Charset.forName("utf-8")));

        // 回复数据到客户端
        System.out.println(new Date() + ": 服务端写出数据");
        ByteBuf out = getByteBuf(ctx);
        ctx.channel().writeAndFlush(out);
    }

    private ByteBuf getByteBuf(ChannelHandlerContext ctx) {
        byte[] bytes = "你好，欢迎来到西部落!".getBytes(Charset.forName("utf-8"));

        ByteBuf buffer = ctx.alloc().buffer();

        buffer.writeBytes(bytes);

        return buffer;
    }
}

结果：