初识netty，写一个简单的demo

 

首先服务端代码：

package com.nettytest;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

import java.util.Scanner;

public class NettyServer {
    public static void main(String[] args) {
        ServerBootstrap serverBootstrap = new ServerBootstrap();

        NioEventLoopGroup boos = new NioEventLoopGroup();
        NioEventLoopGroup worker = new NioEventLoopGroup();
        serverBootstrap
                .group(boos, worker)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<NioSocketChannel>() {
                    protected void initChannel(final NioSocketChannel ch) {
                        ch.pipeline().addLast(new StringDecoder(CharsetUtil.UTF_8));
                        ch.pipeline().addLast(new StringEncoder(CharsetUtil.UTF_8));
                        ch.pipeline().addLast(new SimpleChannelInboundHandler<TextWebSocketFrame>() {
                            @Override
                            public void channelActive(ChannelHandlerContext ctx) {
                                System.out.println("我执行乐乐乐");
                                System.out.println("1"+ctx.channel());
                                Singleton.getSingleton().setChannel(ctx.channel());
                            }
                            protected void channelRead0(ChannelHandlerContext channelHandlerContext, TextWebSocketFrame textWebSocketFrame) throws Exception {

                            }
                        });
                        ch.pipeline().addLast(new SimpleChannelInboundHandler<String>() {
                            @Override
                            protected void channelRead0(ChannelHandlerContext ctx, String msg) {
                                System.out.println("11"+ctx.channel());
                                System.out.println(msg);

                            }
                        });
                    }
                })
                .bind(8000);

        Scanner sc = new Scanner(System.in);
        while (true) {
            String next = sc.next();
            Singleton.getSingleton().getChannel().writeAndFlush(next);
        }


    }
}

其次是客户端代码：

package com.nettytest;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.ReferenceCountUtil;

import java.util.Scanner;

public class NettyClient {
    public static void main(String[] args) throws InterruptedException {
        Bootstrap bootstrap = new Bootstrap();
        NioEventLoopGroup group = new NioEventLoopGroup();

        bootstrap.group(group)
                .channel(NioSocketChannel.class)
                .handler(new ChannelInitializer<Channel>() {
                    @Override
                    protected void initChannel(Channel ch) {
                        ch.pipeline().addLast(new StringEncoder());
                        ch.pipeline().addLast(new ChannelInboundHandlerAdapter(){
                            @Override
                            public void channelRead(ChannelHandlerContext ctx, Object msg) {
                                ByteBuf in = (ByteBuf) msg;
                                try {
                                    System.out.println("客户端接收到消息了:");
                                    while (in.isReadable()) { // (1)
                                        System.out.print((char) in.readByte());
                                        System.out.flush();
                                    }
                                } finally {
                                    ReferenceCountUtil.release(msg); // (2)
                                }
                            }
                        });
                    }
                });

        Channel channel = bootstrap.connect("127.0.0.1", 8000).channel();
        Scanner sc = new Scanner(System.in);
        while (true) {
            String next = sc.next();
            channel.writeAndFlush(next);
        }
    }
}

用来获取客户端Channel的单例:

package com.nettytest;

import io.netty.channel.Channel;

public class Singleton {

    private Channel channel;
    public void setChannel(Channel channel){
        this.channel = channel;
    }

    public Channel getChannel(){
        return this.channel;
    }
    private volatile static Singleton singleton;
    private Singleton (){}
    public static Singleton getSingleton() {
        if (singleton == null) {
            synchronized (Singleton.class) {
                if (singleton == null) {
                    singleton = new Singleton();
                }
            }
        }
        return singleton;
    }

}

其中一点，服务端给客户端发消息，拿到客户端的Channel就可以发送了，所以为了获取客户端的Channel，我使用了单例进行保存。

这些代码可以直接复制，是可以运行的 哦对 得导入netty的依赖

        <dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
            <version>4.1.50.Final</version>
        </dependency>

这个代码不能发送中文，不然它会出现乱码的情况，目前还没有解决。

这里边的有很多匿名内部类，开发中，这些一般也都是单独拿出来进行实现的 然后再将实例写到当前写的匿名内部类的位置。