java Netty应用实例-群聊系统_java netty 示例-优快云博客

本文链接：https://blog.youkuaiyun.com/developerFBI/article/details/137367351

一、实例要求：

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他所有用户，同时可以接受其他用户发送的消息（有服务器转发得到）

5）目的：进一步理解Netty非阻塞网络编程机制。

二、以下为实现代码

1.服务器端GroupChatServer.java

package com.tfq.netty.netty.groupchat;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;

/**
 * @author: fqtang
 * @date: 2024/04/03/13:39
 * @description: 描述
 */
public class GroupChatServer {
	//监听端口
	private int port;

	public GroupChatServer(int port) {
		this.port = port;
	}

	/**
	 * 处理客户端的请求
	 */
	public void run() throws InterruptedException {

		//创建两个线程组
		EventLoopGroup bossGroup = new NioEventLoopGroup(1);
		EventLoopGroup workerGroup = new NioEventLoopGroup(8);
		try {

			ServerBootstrap serverBootstrap = new ServerBootstrap();
			serverBootstrap.group(bossGroup, workerGroup)
				.channel(NioServerSocketChannel.class)
				.option(ChannelOption.SO_BACKLOG, 128)
				.childOption(ChannelOption.SO_KEEPALIVE, true)
				.childHandler(new ChannelInitializer<SocketChannel>() {
					@Override
					protected void initChannel(SocketChannel ch) throws Exception {
						//获取到pipeline
						ChannelPipeline pipeline = ch.pipeline();
						//向pipeline加入一个解码器
						pipeline.addLast("decoder", new StringDecoder());
						//向pipeline加入一个编码器
						pipeline.addLast("encoder", new StringEncoder());
						//加入自己的业务处理handler
						pipeline.addLast(new GroupChatServerHandler());
					}
				});

			System.out.println("netty 服务器启动");
			ChannelFuture channelFuture = serverBootstrap.bind(port)
				.sync();
			channelFuture.channel()
				.closeFuture()
				.sync();
		}finally {
			bossGroup.shutdownGracefully();
			workerGroup.shutdownGracefully();
		}
	}

	public static void main(String[] args) {
		try {
			new GroupChatServer(7888).run();
		} catch(InterruptedException e) {
			throw new RuntimeException(e);
		}
	}

}

服务器端的handler处理：

package com.tfq.netty.netty.groupchat;

import java.text.SimpleDateFormat;
import java.util.Date;

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;

/**
 * @author: fqtang
 * @date: 2024/04/03/13:53
 * @description: 描述
 */
public class GroupChatServerHandler extends SimpleChannelInboundHandler<String> {

	/**
	 * 定义一个channel组，管理所有的channel
	 * GlobalEventExecutor.INSTANCE是全局的事件执行器，是一个单例
	 */
	private static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

	SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

	/**
	 * 表示连接建立，一旦连接，第一个被执行
	 * 将当前channel加入到 channelGroup
	 *
	 * @param ctx
	 * @throws Exception
	 */
	@Override
	public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
		Channel channel = ctx.channel();
		//将该客户加入聊天的信息推送给其他在线的客户端
		//该方法会将channelGroup 中所有的channel 遍历，并发送消息,我们不需要自己遍历
		channels.writeAndFlush(sdf.format(new Date())+" [客户端]" + channel.remoteAddress() + " 加入聊天\n");
		channels.add(channel);
	}

	/**
	 * 表示channel 处于活动上线,提示 xx上线
	 *
	 * @param ctx
	 * @throws Exception
	 */
	@Override
	public void channelActive(ChannelHandlerContext ctx) throws Exception {
		System.out.println(ctx.channel()
			.remoteAddress() + " 在[ "+sdf.format(new Date())+" ] 上线了~");
	}

	/**
	 * 表示channel 处于离线,提示 xx离线
	 *
	 * @param ctx
	 * @throws Exception
	 */
	@Override
	public void channelInactive(ChannelHandlerContext ctx) throws Exception {
		System.out.println(ctx.channel()
			.remoteAddress() + "在 "+sdf.format(new Date())+" 离线了~");
	}

	/**
	 * 断开连接，将XX客户离开信息推送给当前在线的客户
	 *
	 * @param ctx
	 * @throws Exception
	 */
	@Override
	public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
		Channel channel = ctx.channel();
		channels.writeAndFlush("[客户端]" + channel.remoteAddress() + "在 【"+ sdf.format(new Date()) +"】 离开\n");
		System.out.println("移除通道"+channel.hashCode()+",当前通道总数：" + channels.size());
	}

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		//获取当前通道channel
		Channel channel = ctx.channel();
		//这时我们遍历channels,根据不同的情况，返回不同的不同消息
		channels.forEach(c -> {
			if(channel !=c){//不是当前的channel，直接打印消息
				//把当前通道的消息转发给其他通道了
				c.writeAndFlush("[客户]" + channel.remoteAddress()+ "在 【"+ sdf.format(new Date()) + "】 发送了消息:"+ msg +" \n");
			}else {
				c.writeAndFlush("【自己】在 【"+ sdf.format(new Date()) +"】 发送了消息"+msg+"\n");
			}
		});
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		//关闭通道
		ctx.close();
		System.out.println("在 【"+sdf.format(new Date()) +"】 关闭通道，通道总数：" + channels.size());
	}
}

2.客户端GroupChatClient.java

package com.tfq.netty.netty.groupchat;

import java.util.Scanner;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;


/**
 * @author: fqtang
 * @date: 2024/04/04/7:54
 * @description: 描述
 */
public class GroupChatClient {

	private final String host;
	private final int port;

	public GroupChatClient(String host, int port) {
		this.host = host;
		this.port = port;
	}

	public void run() {
		EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

		try {
			Bootstrap bootstrap = new Bootstrap();
			bootstrap.group(eventLoopGroup)
				.channel(NioSocketChannel.class)
				.handler(new ChannelInitializer<SocketChannel>() {
					@Override
					protected void initChannel(SocketChannel ch) throws Exception {
						//得到pipeline
						ChannelPipeline pipeline = ch.pipeline();
						//加入相关handler的解码器
						pipeline.addLast("decoder", new StringDecoder());
						//加入相关handler的编码器
						pipeline.addLast("encoder", new StringEncoder());
						//加入自定义的handler
						pipeline.addLast(new GroupChatClientHandler());
					}
				});
			//连接服务器返回通道
			ChannelFuture channelFuture = bootstrap.connect(host, port)
				.sync();
			Channel channel = channelFuture.channel();

			if(channelFuture.isSuccess()) {
				System.out.println("本地ip:"+channel.localAddress()+",连接服务器ip: "+channel.remoteAddress() + " 成功");
			}

			Scanner scanner = new Scanner(System.in);
			while(scanner.hasNextLine()) {
				channel.writeAndFlush(scanner.nextLine());
			}

			//给关闭监听进行通道
			channel.closeFuture()
				.sync();

		} catch(InterruptedException e) {
			throw new RuntimeException(e);
		} finally {
			eventLoopGroup.shutdownGracefully();
		}

	}

	public static void main(String[] args) {
		new GroupChatClient("127.0.0.1", 7888).run();
	}
}

客户端的handler处理

package com.tfq.netty.netty.groupchat;

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

/**
 * @author: fqtang
 * @date: 2024/04/04/8:16
 * @description: 描述
 */
public class GroupChatClientHandler extends SimpleChannelInboundHandler<String> {

	@Override
	protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
		System.out.println(msg.trim());
	}
}

先运行GroupChatServer.java，然后运行多个GroupChatClient客户端。若用Idea开发则设置运行多个客户。如下图：