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🗣 Wd提问: netty聊天服务器

🤖 Ai回答:
Netty 聊天服务器实现

下面是一个基于 Netty 4.x 的简单聊天服务器实现，支持群聊功能。这个示例展示了如何使用 Netty 构建一个基本的聊天服务器。

服务器端代码

java
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;
import io.netty.util.concurrent.DefaultEventExecutorGroup;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class ChatServer {
private int port;
private Map<String, Channel channels = new ConcurrentHashMap<();
private DefaultEventExecutorGroup executorGroup;

public ChatServer(int port) {
this.port = port;
// 创建线程池用于处理广播操作，避免阻塞Netty的I/O线程
executorGroup = new DefaultEventExecutorGroup(16);
}

public void run() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();

try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new StringDecoder());
ch.pipeline().addLast(new StringEncoder());
ch.pipeline().addLast(new ChatServerHandler(ChatServer.this));
}
})
.option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);

System.out.println(Chat server is starting at port + port);
ChannelFuture f = b.bind(port).sync();
System.out.println(Chat server started successfully);

f.channel().closeFuture().sync();
} finally {
executorGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}

public void addChannel(String id, Channel channel) {
channels.put(id, channel);
}

public void removeChannel(String id) {
channels.remove(id);
}

public void broadcastMessage(String message) {
executorGroup.execute(() - {
for (Channel channel : channels.values()) {
channel.writeAndFlush(message + \n);
}
});
}

public static void main(String[] args) throws Exception {
int port = 8080;
if (args.length 0) {
port = Integer.parseInt(args[0]);
}
new ChatServer(port).run();
}
}

class ChatServerHandler extends ChannelInboundHandlerAdapter {
private ChatServer server;
private String id;

public ChatServerHandler(ChatServer server) {
this.server = server;
}

@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
// 生成一个唯一的ID，使用短ID
id = ctx.channel().id().asShortText();
server.addChannel(id, ctx.channel());
System.out.println(Client connected: + id);
server.broadcastMessage(User + id + has joined the chat);
}

@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
server.removeChannel(id);
System.out.println(Client disconnected: + id);
server.broadcastMessage(User + id + has left the chat);
}

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
String message = (String) msg;
System.out.println(Received message from + id + : + message);

// 如果是quit命令，断开连接
if (quit.equalsIgnoreCase(message)) {
ctx.close();
return;
}

// 广播消息，不包括发送者自己
server.broadcastMessage([ + id + ] + message);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}

客户端代码

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

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

public class ChatClient {
private String host;
private int port;

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

public void run() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new StringDecoder());
ch.pipeline().addLast(new StringEncoder());
ch.pipeline().addLast(new ChatClientHandler());
}
});

System.out.println(Connecting to server at + host + : + port);
ChannelFuture f = b.connect(host, port).sync();
System.out.println(Connected to server);

// 读取用户输入
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true) {
String line = reader.readLine();
if (line == null) {
break;
}
f.channel().writeAndFlush(line);
}
} finally {
group.shutdownGracefully();
}
}

public static void main(String[] args) throws Exception {
String host = localhost;
int port = 8080;
if (args.length 0) {
port = Integer.parseInt(args[0]);
}
if (args.length 1) {
host = args[1];
}
new ChatClient(host, port).run();
}
}

class ChatClientHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
String message = (String) msg;
System.out.print(message);
}

@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}

使用说明

1、编译和运行服务器:
bash
编译服务器
javac ChatServer.java ChatServerHandler.java

运行服务器 (默认端口8080)
java ChatServer

或指定端口
java ChatServer 9090

2、运行客户端:
bash
编译客户端
javac ChatClient.java ChatClientHandler.java

连接到服务器 (默认localhost:8080)
java ChatClient

或指定服务器地址和端口
java ChatClient 192.168.1.100 9090

关键特性

1、多客户端支持：使用 `ConcurrentHashMap` 管理所有连接的客户端通道
2、广播消息：所有客户端都能看到其他客户端发送的消息
3、连接状态管理：自动处理客户端连接和断开
4、非阻塞I/O：使用Netty的事件驱动模型，高效处理大量并发连接
5、优雅关闭：正确处理线程组的关闭
6、简单命令：客户端输入quit可退出聊天

优化方向

实际生产环境中，可以考虑以下改进：

1、用户身份验证：添加用户名和密码验证
2、私聊功能：实现点对点消息
3、消息历史：存储和发送历史消息
4、消息加密：使用SSL/TLS加密通信
5、房间功能：支持多个聊天室
6、消息过滤：防止不当内容

依赖

确保项目中包含Netty依赖（Maven示例）：

xml
<dependency
<groupIdio.netty</groupId
<artifactIdnetty-all</artifactId
<version4.1.72.Final</version
</dependency

这个示例展示了Netty构建聊天服务器的核心原理，您可以在此基础上扩展更多功能。Netty的高性能和异步特性使其成为构建实时聊天应用的理想选择。

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