Netty学习——基于netty实现简单的客户端聊天小程序

package com.dawa.netty.chatexample;

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

/**
 * @Title: MyChatServer
 * @Author: 大娃
 * @Date: 2019/11/26 09:44
 * @Description: 客户端
 */
public class MyChatServer {
    public static void main(String[] args) throws InterruptedException {
        //定义两个 循环组
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            //服务器端 启动类
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            //启动类装载两个 循环组
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                    .childHandler(new MyChatServerInitializer());//初始化器

            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();

        }finally {
            //关闭循环组
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

package com.dawa.netty.chatexample;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;

/**
 * @Title: MyChatServerHandler
 * @Author: 大娃
 * @Date: 2019/11/26 09:54
 * @Description:  消息的广播
 * ABC 三个客户端，分别建立服务器的链接
 * A，第一个用户，没必要通知
 * B，A，B和服务器的控制台都提示  B已经上线，
 * C，ABC和服务器端，都是C上线
 *
 *
 * 自己想的：根据生命周期，当注册的时候，提示已经上线，当注销的时候，提示已经下线。
 * 当发送一个消息到服务器端的时候，服务器端广播一下。  判断如果是自己的IP的话，提示自己。不是的话，显示IP
 *
 * netty都是通过响应的回调方法，来进行实现的
 * 1.当连接建立好的时候，就代表有一个客户端和服务端建立起连接了、。  handlerAdded
 */
public class MyChatServerHandler extends SimpleChannelInboundHandler<String> {

    //用来保存一个个的channel对象的。
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

    //收到任何一个消息之后，的回调函数
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.forEach(ch -> {
            if (channel != ch) {
                ch.writeAndFlush(channel.remoteAddress() + "发送的消息：" + msg + "\n");
            } else {
                ch.writeAndFlush("【自己】" + "发送的消息：" + msg + "\n" );
            }
        });
    }

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

    /**
     * 1.当连接建立好的时候，就代表有一个客户端和服务端建立起连接了。  handlerAdded
     * @param ctx
     * @throws Exception
     */
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        //1.建立起连接
        Channel channel = ctx.channel();
        //2.进行广播。
        channelGroup.writeAndFlush("【服务器】：" + channel.remoteAddress() + "加入\n");
        //3.添加到组
        channelGroup.add(channel); //服务器端是不是需要将所有已经建立起连接的channel 保存起来？ channelGroup
    }

    /**
     * 2.当离开的时候
     * @param ctx
     * @throws Exception
     */
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("【服务器】：" + channel.remoteAddress() + "离开 \n ");
        //无需手工的移除，  会自动将断掉的链接移除  。 现在先不管，以后可以看看
        // channelGroup.remove(channel);
    }


    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+" 上线");
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        System.out.println(channel.remoteAddress()+" 下线");
    }
}

package com.dawa.netty.chatexample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

/**
 * @Title: MyChatServerInitializer
 * @Author: 大娃
 * @Date: 2019/11/26 09:46
 * @Description:
 */
public class MyChatServerInitializer extends ChannelInitializer<SocketChannel> {
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        //第一个解码器：自带的。 根据分隔符来进行解析
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096, Delimiters.lineDelimiter()));
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        //Handler
        pipeline.addLast(new MyChatServerHandler());
    }
}

package com.dawa.netty.chatexample;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;

import java.io.BufferedReader;
import java.io.InputStreamReader;

/**
 * @Title: MyChatClient
 * @Author: 大娃
 * @Date: 2019/11/26 14:39
 * @Description:
 */
public class MyChatClient {
    public static void main(String[] args) throws Exception {
        //循环组，一个就够用了。客户端
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

        try {
            //客户端使用的是bootstrap，
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).handler(new MyChatClientInitializer());

            //注意此处，使用的是connect,不是使用的bind
            Channel channel = bootstrap.connect("localhost", 8899).sync().channel();

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

            for (; ; ) {
                channel.writeAndFlush(br.readLine()+ "\r\n");
            }

        } finally {
            eventLoopGroup.shutdownGracefully();
        }


    }
}

package com.dawa.netty.chatexample;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;

import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.Delimiters;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.CharsetUtil;

/**
 * @Title: MyChatClientInitializer
 * @Author: 大娃
 * @Date: 2019/11/26 14:42
 * @Description:
 */
public class MyChatClientInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        //添加Handler
        ChannelPipeline channelPipeline = ch.pipeline();
        channelPipeline.addLast(new DelimiterBasedFrameDecoder(4096, Delimiters.lineDelimiter()));
        channelPipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        channelPipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        //添加自己的Handler
        pipeline.addLast(new MyChatClientHandler());
    }
}

package com.dawa.netty.chatexample;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;

/**
 * @Title: MyChatClientHandler
 * @Author: 大娃
 * @Date: 2019/11/26 14:45
 * @Description:
 */
public class MyChatClientHandler extends SimpleChannelInboundHandler<String> {
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }
}