从入门到超神进阶的Netty群聊系统

服务端

服务端一样的需要创建bossgroup 和 workgroup , 然后使用serverbootstrap 来配置netty和启动netty。

public class nettygroupchatserver {
    public static void main(string[] args) {
        new nettygroupchatserver().start();
    }
    //监听
   public void start(){
        //循环组
       nioeventloopgroup bossgroup = new nioeventloopgroup();
       nioeventloopgroup workgroup = new nioeventloopgroup();
       //启动引导
       serverbootstrap bootstrap = new serverbootstrap();
       //netty配置
       bootstrap.group(bossgroup,workgroup)
               .option(channeloption.so_backlog,32)
               .childoption(channeloption.so_keepalive,true)
               .channel(nioserversocketchannel.class)
               .childhandler(new channelinitializer<socketchannel>() {
                   @override
                   protected void initchannel(socketchannel channel) throws exception {
                       //解码器
                       channel.pipeline().addlast("decoder", new stringdecoder());
                       //编码器
                       channel.pipeline().addlast("encoder",new stringencoder());
                       //处理器
                       channel.pipeline().addlast("nettygroupchathandler",new nettygroupchatserverhandler());
                   }
               });
       try {
           //启动服务
           channelfuture future = bootstrap.bind(new inetsocketaddress("127.0.0.1", 8888)).sync();
           future.channel().closefuture().sync();
       } catch (interruptedexception e) {
           e.printstacktrace();
       }finally {
           //关闭资源
           bossgroup.shutdowngracefully();
           workgroup.shutdowngracefully();
       }
   }
}

服务端处理器我们通过继承 simplechannelinboundhandler 入站handler来处理消息。

其中提供了几个方法

• channelread0 ()：读取消息
• handlerremoved ()：客户端断开
• handleradded ()：客户端建立连接
• exceptioncaught ()：出现异常

具体代码如下

public class nettygroupchatserverhandler extends simplechannelinboundhandler<string> {
    //把所有客户端的channel保存起来
    private static channelgroup channels = new defaultchannelgroup(globaleventexecutor.instance);
    private static simpledateformat dateformat = new simpledateformat("yyyy-mm-dd hh:mm:ss");
    @override
    protected void channelread0(channelhandlercontext ctx, string msg) throws exception {
        string message = dateformat.format(new date())+":%s:"+msg;
        //消息转发给所有的客户端
        channels.foreach(channel -> {
            if(channel == ctx.channel()){
                string sendmsg = string.format(message, "我");
                channel.writeandflush(sendmsg);
                system.out.println(sendmsg);

            }else{
                string sendmsg = string.format(message, ctx.channel().remoteaddress());
                channel.writeandflush(sendmsg);
                system.out.println(sendmsg);
            }
        });
    }
    //断开连接 , 把消息广播给其他客户端
    @override
    public void handlerremoved(channelhandlercontext ctx) throws exception {
        string message = dateformat.format(new date())+":"+ctx.channel().remoteaddress()+":断开连接";
        channels.writeandflush(message);
        system.out.println(message);
    }
    //建立连接
    @override
    public void handleradded(channelhandlercontext ctx) throws exception {
        string message = dateformat.format(new date())+":"+ctx.channel().remoteaddress()+":加入聊天室";
        //自动把消息广播给其客户端
        channels.writeandflush(message);
        //客户端加入组
        channels.add(ctx.channel());
        system.out.println(message);
    }
    //出现异常
    @override
    public void exceptioncaught(channelhandlercontext ctx, throwable cause) throws exception {
        ctx.channel().close();
    }
    //客户端退出
    @override
    public void channelinactive(channelhandlercontext ctx) throws exception {
        string message = dateformat.format(new date())+":"+ctx.channel().remoteaddress()+":退出聊天室";
        system.out.println(message);
    }
    //客户端出于活动
    @override
    public void channelactive(channelhandlercontext ctx) throws exception {
        string message = dateformat.format(new date())+":"+ctx.channel().remoteaddress()+":上线啦";
        system.out.println(message);
    }
}

客户端

客户端需要创建一个循环事件组，然后通过bootstrap去启动,然后扫描键盘输入作为数据源来把信息发送给服务端

public class nettygroupchatclient {
    public static void main(string[] args) {
        new nettygroupchatclient().start();
    }
    public void start(){
        nioeventloopgroup eventloopgroup = new nioeventloopgroup();
        bootstrap bootstrap = new bootstrap();
        bootstrap.group(eventloopgroup)
                .channel(niosocketchannel.class)
                .handler(new channelinitializer<socketchannel>() {
                    @override
                    protected void initchannel(socketchannel channel) throws exception {
                        //解码器
                        channel.pipeline().addlast("decoder", new stringdecoder());
                        //编码器
                        channel.pipeline().addlast("encoder",new stringencoder());
                        //处理器
                        channel.pipeline().addlast("nettygroupchatclienthandler",new nettygroupchatclienthandler());
                    }
                });
        try {
            channelfuture future = bootstrap.connect(new inetsocketaddress("127.0.0.1", 8888)).sync();
            //通道
            channel channel = future.channel();
            //扫描键盘输入
            scanner scanner = new scanner(system.in);
            while(scanner.hasnextline()){
                string message = scanner.nextline();
                //发送数据
                channel.writeandflush(message);
            }
        } catch (interruptedexception e) {
        }finally {
            eventloopgroup.shutdowngracefully();
        }
    }
}

对于处理器只需要接收服务端转发过来的消息即可

public class nettygroupchatclienthandler extends simplechannelinboundhandler<string> {
    @override
    protected void channelread0(channelhandlercontext ctx, string msg) throws exception {
        system.out.println(msg);
    }
}

启动服务端和多个客户端，效果如下

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