服务端代码

package chat.server;

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;

public class ChatServer {

    public static void main(String[] args) throws InterruptedException {
        // 接收连接,但是不处理
        EventLoopGroup parentGroup = new NioEventLoopGroup();
        // 真正处理连接的group
        EventLoopGroup childGroup = new NioEventLoopGroup();
        
        try {
            //加载Initializer
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(parentGroup, childGroup)
                           .channel(NioServerSocketChannel.class)
                           //这里的childHandler是服务于childGroup的,如果直接使用
                           //handler方法添加处理器,则是服务于parentGroup的
                           .childHandler(new ChatServerInitializer());
            
            //绑定监听端口
            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        }
        finally {
            parentGroup.shutdownGracefully();
            childGroup.shutdownGracefully();
        }
    }
}

package chat.server;

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;

public class ChatServerInitializer extends ChannelInitializer<SocketChannel>{
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();
        
        //1、按照分隔符切割消息
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096,Delimiters.lineDelimiter()));

        //2、socket编程中需要对字符串进行编码解码
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        
        pipeline.addLast(new ChatServerHandler());
    }
}

package chat.server;

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;

public class ChatServerHandler extends SimpleChannelInboundHandler<String>{
    //存放所有channel对象
    private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE); 
    
    @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:"+msg+"\n");
            }
            else {
                ch.writeAndFlush("本人发的消息:"+msg + "\n");
            }
        });
    }
    
    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("有人:"+channel.remoteAddress()+"加入\n");
        
        channelGroup.add(channel);
    }
    
    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        Channel channel = ctx.channel();
        channelGroup.writeAndFlush("有人:"+channel.remoteAddress()+"离开\n");       
    }
    
    @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() + "上线");
    }
    
}

客户端代码

package chat.client;

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

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;

public class ChatClient {

    public static void main(String[] args) throws InterruptedException, IOException {
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();
        
        try {
            //加载Initializer
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup)
                           .channel(NioSocketChannel.class)
                           .handler(new ChatClientInitializer());
            
            //连接服务端
            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 chat.client;

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;

public class ChatClientInitializer extends ChannelInitializer<SocketChannel>{
    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
        //1、按照分隔符切割消息
        pipeline.addLast(new DelimiterBasedFrameDecoder(4096,Delimiters.lineDelimiter()));

        //2、socket编程中需要对字符串进行编码解码
        pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
        pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
        
        //3、添加自定义处理器
        pipeline.addLast(new ChatClientHandler());
    }
}

package chat.client;

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

public class ChatClientHandler extends SimpleChannelInboundHandler<String>{
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(msg);
    }
}

当有新的客户端连接到服务器的时候,ChatServerHandler的channelRead0方法会给所有上线的客户端发送消息。

ChatClient的main方法中,会从System.in中获取用户的输入,并写到服务端。

csdn code 路径

这个项目的源代码放置在csdn code上,欢迎访问。

netty_study