Netty实现群聊系统

今天药忘吃喽~ 2022-12-31 13:25 252阅读 0赞

# 1 需求 #

(1) 编写一个 Netty群聊系统,实现服务器端和客户端之间的数据简单通讯(非阻塞)  
(2) 实现多人群聊  
(3) 服务器端:可以监测用户上线,离线,并实现消息转发功能  
(4) 客户端:通过 channel可以无阻塞发送消息给其它所有用户,同时可以接受其它用  
(5) 户发送的消息(有服务器转发得到)  
目的:进一步理解Net非阻塞网络编程机制

# 2 Code #

## 2.1 GroupChatConsts ##

public final class GroupChatConsts { 
    
        private GroupChatConsts() { 
        }
    
    
        public static final Integer port = 8888;
    
        public static final String host = "127.0.0.1";
    
    }

## 2.2 GroupChatServer ##

### (1) GroupChatServerHandler ###

package com.rosh.netty.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;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    /** * @Description: * @Author: rosh * @Date: 2020/12/29 22:59 */
    public class GroupChatServerHandler extends SimpleChannelInboundHandler<String> { 
    
    
        /** * 定义一个channel组，管理所有的channel */
        private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
    
    
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    
        /** * 当建立连接时，第一个被执行 */
        @Override
        public void handlerAdded(ChannelHandlerContext ctx) throws Exception { 
            Channel channel = ctx.channel();
            //通知其他客户，有人加入该聊天室
            channelGroup.writeAndFlush("【客户端】 " + sdf.format(new Date()) + channel.remoteAddress() + " 加入聊天 \n");
            //加入聊天
            channelGroup.add(channel);
        }
    
    
        /** * 表示channel处于一个活跃的状态 */
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception { 
            System.out.println("【" + ctx.channel().remoteAddress() + "】 " + sdf.format(new Date()) + " 上线了 ~");
        }
    
        /** * 表示channel处于不活动的状态 */
        @Override
        public void channelInactive(ChannelHandlerContext ctx) throws Exception { 
    
            System.out.println("【" + ctx.channel().remoteAddress() + "】 " + sdf.format(new Date()) + " 离线了 ~");
        }
    
    
        /** * channel断开连接会被触发 */
        @Override
        public void handlerRemoved(ChannelHandlerContext ctx) throws Exception { 
            Channel channel = ctx.channel();
            channelGroup.writeAndFlush("【客户端】 " + sdf.format(new Date()) + channel.remoteAddress() + " 离开了\n");
        }
    
        /** * 转发消息 */
        @Override
        protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception { 
            Channel channel = ctx.channel();
            channelGroup.forEach(ch -> { 
                if (channel != ch) { 
                    ch.writeAndFlush("【客户】" + sdf.format(new Date()) + channel.remoteAddress() + "发送了消息: " + msg + "\n");
                } else { 
                    ch.writeAndFlush("【自己】" + sdf.format(new Date()) + "发送了消息: " + msg + "\n");
                }
            });
        }
    
        /** * 发生异常时 关闭通道 */
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { 
            ctx.close();
        }
    }

### （2） GroupChatServerChannelInitializer ###

public class GroupChatServerChannelInitializer extends ChannelInitializer<SocketChannel> { 
    
        @Override
        protected void initChannel(SocketChannel ch) throws Exception { 
    
            ChannelPipeline pipeline = ch.pipeline();
    
            //解码器
            pipeline.addLast("decoder", new StringDecoder());
            //编码器
            pipeline.addLast("encoder", new StringEncoder());
            //加入自己业务handler
            pipeline.addLast("serverHandler", new GroupChatServerHandler());
    
    
        }
    }

### (3) GroupChatServerHandler ###

public class GroupChatServer { 
    
    
        public static void main(String[] args) { 
            NioEventLoopGroup bossGroup = new NioEventLoopGroup(1);
            NioEventLoopGroup workerGroup = new NioEventLoopGroup();
            try { 
    
                ServerBootstrap serverBootstrap = new ServerBootstrap();
                serverBootstrap.group(bossGroup, workerGroup)
                        //nio
                        .channel(NioServerSocketChannel.class)
                        //bossGroup,option,服务端接受连接的队列长度，如果队列已满，客户端连接将被拒绝。
                        .option(ChannelOption.SO_BACKLOG, 128)
                        //workerGroup,option,是否启动心跳包活机制
                        .childOption(ChannelOption.SO_KEEPALIVE, true)
                        .childHandler(new GroupChatServerChannelInitializer());
                //绑定端口
                ChannelFuture channelFuture = serverBootstrap.bind(GroupChatConsts.port).sync();
                //监听关闭事件
                channelFuture.channel().closeFuture().sync();
            } catch (InterruptedException e) { 
                e.printStackTrace();
            } finally { 
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        }
    
    
    }

## 2.3 GroupChatClient ##

### (1) GroupChatClientHandler ###

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

### (2) GroupChatClientChannelInitializetr ###

public class GroupChatClientChannelInitializetr  extends ChannelInitializer<SocketChannel>{ 
        @Override
        protected void initChannel(SocketChannel ch) throws Exception { 
    
            ChannelPipeline pipeline = ch.pipeline();
            //解码器
            pipeline.addLast("decoder", new StringDecoder());
            //编码器
            pipeline.addLast("encoder", new StringEncoder());
            //自定义handler
            pipeline.addLast("clientHandler", new GroupChatClientHandler());
        }
    }

### (3) GroupChatClient ###

public class GroupChatClient { 
    
        public static void main(String[] args) { 
            EventLoopGroup group = new NioEventLoopGroup();
            try { 
    
                Bootstrap bootstrap = new Bootstrap();
                bootstrap.group(group).channel(NioSocketChannel.class)
                        .handler(new GroupChatClientChannelInitializetr());
                ChannelFuture channelFuture = bootstrap.connect(GroupChatConsts.host, GroupChatConsts.port).sync();
                //输入信息
                Channel channel = channelFuture.channel();
                Scanner scanner = new Scanner(System.in);
                while (scanner.hasNext()) { 
                    String msg = scanner.nextLine();
                    channel.writeAndFlush(msg + "\n");
                }
            } catch (InterruptedException e) { 
                e.printStackTrace();
            } finally { 
                group.shutdownGracefully();
            }
    
        }
    
    }

# 3 测试 #

(1) 启动服务端，启动3个客户端  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70]  
(2) 发送消息  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 3]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70]: /images/20221120/ff6ea790569642e89db69331c3ef8fc6.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/2020123000180856.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20201230001824490.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20201230001829869.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM0MTI1OTk5,size_16,color_FFFFFF,t_70