netty实现群聊功能
【概述】
实现一个网络群聊工具。参与聊天的客户端消息是通过服务端进行广播的。
主要由两块组成:聊天服务器端(ChatServer)和聊天客户端(ChatClient)。
聊天服务器(ChatServer)功能概述 :
1.监听所有客户端的接入、断线
2.有客户端A接入聊天室时,将接入消息发给除了客户端A的其他客户端
3.当客户端A退出聊天室时,将退出消息发给除了客户端A的其他客户端
4.当客户端A发送消息到聊天室时,将消息转发给除了客户端A的其他客户端
聊天客户端(ChatClient)功能概述 :
1.发送消息至聊天服务器
2.接收聊天服务器发送过来的所有消息
【pom依赖】
<!--netty--> <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>4.1.36.Final</version> </dependency> <!--lombok依赖--> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.18.6</version> <scope>provided</scope> </dependency>
【服务端启动器 ChatServer 】
package com.test.server; 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.LineBasedFrameDecoder; import io.netty.handler.codec.string.StringDecoder; import io.netty.handler.codec.string.StringEncoder; /** * 群聊服务端 * */ public class ChatServer { private final int port; public ChatServer(int port) { this.port = port; } public void start() throws InterruptedException { EventLoopGroup parentGroup = new NioEventLoopGroup(); EventLoopGroup childGroup = new NioEventLoopGroup(); try { ServerBootstrap serverBootstrap = new ServerBootstrap(); serverBootstrap.group(parentGroup, childGroup).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<SocketChannel>() { protected void initChannel(SocketChannel sc) throws Exception { ChannelPipeline pipeline = sc.pipeline(); //添加一个基于行的解码器 pipeline.addLast(new LineBasedFrameDecoder(2048)); pipeline.addLast(new StringDecoder()); pipeline.addLast(new StringEncoder()); pipeline.addLast(new ChatServerHandler()); } }).option(ChannelOption.SO_BACKLOG, 128).option(ChannelOption.SO_KEEPALIVE, true); ChannelFuture future = serverBootstrap.bind(port).sync(); System.out.println("服务器已启动"); future.channel().closeFuture().sync(); } finally { parentGroup.shutdownGracefully(); childGroup.shutdownGracefully(); } } public static void main(String[] args) throws InterruptedException { new ChatServer(8888).start(); } }
【ChatServerHandler】
package com.test.server; import io.netty.channel.Channel; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import io.netty.channel.group.ChannelGroup; import io.netty.channel.group.DefaultChannelGroup; import io.netty.util.concurrent.GlobalEventExecutor; /** * 处理聊天服务器的各种情况 * */ public class ChatServerHandler extends ChannelInboundHandlerAdapter { // 创建一个ChannelGroup,其是一个线程安全的集合,其中存放着与当前服务器相连接的所有Active状态的Channel // GlobalEventExecutor是一个单例、单线程的EventExecutor,是为了保证对当前group中的所有Channel的处理 // 线程是同一个线程 private static ChannelGroup group = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE); // 只要有客户端Channel给当前的服务端发送了消息,那么就会触发该方法的执行 @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { // 获取到向服务器发送消息的channel Channel channel = ctx.channel(); // 这里要实现将消息广播给所有group中的客户端Channel // 发送给自己的消息与发送给大家的消息是不一样的 group.forEach(ch -> { if (ch != channel) { ch.writeAndFlush(channel.remoteAddress() + ":" + msg + "\n"); } else { channel.writeAndFlush("me:" + msg + "\n"); } }); } // 只要有客户端Channel与服务端连接成功就会执行这个方法 @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { // 获取到当前与服务器连接成功的channel Channel channel = ctx.channel(); System.out.println(channel.remoteAddress() + "---上线"); group.writeAndFlush(channel.remoteAddress() + "---上线\n"); // 将当前channel添加到group中 group.add(channel); } // 只要有客户端Channel断开与服务端的连接就会执行这个方法 @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { // 获取到当前要断开连接的Channel Channel channel = ctx.channel(); System.out.println(channel.remoteAddress() + "------下线"); group.writeAndFlush(channel.remoteAddress() + "下线,当前在线人数:" + group.size() + "\n"); // group中存放的都是Active状态的Channel,一旦某Channel的状态不再是Active, // group会自动将其从集合中踢出,所以,下面的语句不用写 // remove()方法的应用场景是,将一个Active状态的channel移出group时使用 // group.remove(channel); } /** * 当Channel中的数据在处理过程中出现异常时会触发该方法的执行 * * @param ctx 上下文 * @param cause 发生的异常对象 * @throws Exception */ @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } }
【客户端启动类ChatClient】
package com.test.client; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelPipeline; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioSocketChannel; import io.netty.handler.codec.LineBasedFrameDecoder; import io.netty.handler.codec.string.StringDecoder; import io.netty.handler.codec.string.StringEncoder; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; /** * 群聊客户端 * */ public class ChatClient { private final String host; private final int port; public ChatClient(String host, int port) { this.host = host; this.port = port; } public void start() { NioEventLoopGroup group = new NioEventLoopGroup(); Bootstrap bootstrap = new Bootstrap(); try { bootstrap.group(group).channel(NioSocketChannel.class).handler(new ChannelInitializer<SocketChannel>() { @Override protected void initChannel(SocketChannel ch) throws Exception { ChannelPipeline pipeline = ch.pipeline(); pipeline.addLast(new LineBasedFrameDecoder(2048)); pipeline.addLast(new StringDecoder()); pipeline.addLast(new StringEncoder()); pipeline.addLast(new ChatClientHandler()); } }); ChannelFuture future = bootstrap.connect(host, port).sync(); // 获取键盘输入 InputStreamReader is = new InputStreamReader(System.in, "UTF-8"); BufferedReader br = new BufferedReader(is); // 将输入的内容写入到Channel while (true) { //br.readLine()中执行fill()方法获取输入数据,获取不到时会发生阻塞,直到获取到数据为止 future.channel().writeAndFlush(br.readLine() + "\r\n"); } } catch (InterruptedException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { group.shutdownGracefully(); } } public static void main(String[] args) { new ChatClient("127.0.0.1", 8888).start(); } }
【ChatClientHandler】
package com.test.client; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; /** * 客户端处理 * */ public class ChatClientHandler extends SimpleChannelInboundHandler<String> { @Override protected void channelRead0(ChannelHandlerContext channelHandlerContext, String s) throws Exception { System.out.println(s); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ctx.close(); } }
【运行结果】
[1.启动群聊服务端]
[2.启动群聊客户端01]
[2.启动群聊客户端02]
[3.发送消息测试]
[4.下线测试]