目录

• 一、创建项目
• 二、编写代码
• 三、运行测试
• 参考资料

一、创建项目

创建Spring Initializr项目：

下一个界面点击finish即可。
添加依赖
打开pom.xml使用Alt+Insert快捷键弹出Generate框，选择Dependency

在框内搜索io.netty:netty-all和com.google.code.gson:gson,点击Add

或者直接复制以下代码到dependencies标签内：

		<dependency>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
        </dependency>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
        </dependency>

然后点击右下角的import changes:

二、编写代码

项目架构：

User:

package com.example.chat;

import java.util.Objects;

public class User {

    public String id;
    public String nickname;

    public User(String id, String nickname) {
        super();
        this.id = id;
        this.nickname = nickname;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getNickname() {
        return nickname;
    }

    public void setNickname(String nickname) {
        this.nickname = nickname;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;
        User user = (User) o;
        return id.equals(user.getId());
    }

    @Override
    public int hashCode() {

        return Objects.hash(id);
    }

    public String getUid() {

        return id;
    }
}

ChatApplication:

package com.example.chat;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.env.Environment;

import java.net.InetAddress;
import java.net.UnknownHostException;

@SpringBootApplication
public class ChatApplication {

    public static void main(String[] args) throws UnknownHostException {
        ConfigurableApplicationContext application = SpringApplication.run(ChatApplication.class, args);
        Environment env = application.getEnvironment();
        String host = InetAddress.getLocalHost().getHostAddress();
        String port = env.getProperty("server.port");
        System.out.println("[----------------------------------------------------------]");
        System.out.println("聊天室启动成功！点击进入:\t http://" + host + ":" + port);
        System.out.println("[----------------------------------------------------------");
        SocketServer.inst().run(53134);
    }

}

SessionGroup:

package com.example.chat;

import com.google.gson.Gson;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.ChannelGroupFuture;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.ImmediateEventExecutor;
import org.springframework.util.StringUtils;

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

public final class SessionGroup {

    private static SessionGroup singleInstance = new SessionGroup();

    // 组的映射
    private ConcurrentHashMap<String, ChannelGroup> groupMap = new ConcurrentHashMap<>();

    public static SessionGroup inst() {
        return singleInstance;
    }

    public void shutdownGracefully() {

        Iterator<ChannelGroup> groupIterator = groupMap.values().iterator();
        while (groupIterator.hasNext()) {
            ChannelGroup group = groupIterator.next();
            group.close();
        }
    }

    public void sendToOthers(Map<String, String> result, SocketSession s) {
        // 获取组
        ChannelGroup group = groupMap.get(s.getGroup());
        if (null == group) {
            return;
        }
        Gson gson=new Gson();
        String json = gson.toJson(result);
        // 自己发送的消息不返回给自己
//      Channel channel = s.getChannel();
        // 从组中移除通道
//      group.remove(channel);
        ChannelGroupFuture future = group.writeAndFlush(new TextWebSocketFrame(json));
        future.addListener(f -> {
            System.out.println("完成发送："+json);
//          group.add(channel);//发送消息完毕重新添加。

        });
    }

    public void addSession(SocketSession session) {

        String groupName = session.getGroup();
        if (StringUtils.isEmpty(groupName)) {
            // 组为空，直接返回
            return;
        }
        ChannelGroup group = groupMap.get(groupName);
        if (null == group) {
            group = new DefaultChannelGroup(ImmediateEventExecutor.INSTANCE);
            groupMap.put(groupName, group);
        }
        group.add(session.getChannel());
    }

    /**
     * 关闭连接， 关闭前发送一条通知消息
     */
    public void closeSession(SocketSession session, String echo) {
        ChannelFuture sendFuture = session.getChannel().writeAndFlush(new TextWebSocketFrame(echo));
        sendFuture.addListener(new ChannelFutureListener() {
            public void operationComplete(ChannelFuture future) {
                System.out.println("关闭连接："+echo);
                future.channel().close();
            }
        });
    }

    /**
     * 关闭连接
     */
    public void closeSession(SocketSession session) {

        ChannelFuture sendFuture = session.getChannel().close();
        sendFuture.addListener(new ChannelFutureListener() {
            public void operationComplete(ChannelFuture future) {
                System.out.println("发送所有完成："+session.getUser().getNickname());
            }
        });

    }

    /**
     * 发送消息
     * @param ctx 上下文
     * @param msg 待发送的消息
     */
    public void sendMsg(ChannelHandlerContext ctx, String msg) {
        ChannelFuture sendFuture = ctx.writeAndFlush(new TextWebSocketFrame(msg));
        sendFuture.addListener(f -> {//发送监听
            System.out.println("对所有发送完成："+msg);
        });
    }
}

SocketServer:

package com.example.chat;

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.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketServerCompressionHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
import io.netty.handler.timeout.IdleStateHandler;

import java.util.concurrent.TimeUnit;
import java.util.logging.SocketHandler;

public class SocketServer {

    private static SocketServer wbss;

    private static final int READ_IDLE_TIME_OUT = 60; // 读超时
    private static final int WRITE_IDLE_TIME_OUT = 0;// 写超时
    private static final int ALL_IDLE_TIME_OUT = 0; // 所有超时

    public static SocketServer inst() {
        return wbss = new SocketServer();
    }

    public void run(int port) {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        ServerBootstrap b = new ServerBootstrap();
        b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer <SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {
                        ChannelPipeline pipeline = ch.pipeline();
                        // Netty自己的http解码器和编码器，报文级别 HTTP请求的解码和编码
                        pipeline.addLast(new HttpServerCodec());
                        // ChunkedWriteHandler 是用于大数据的分区传输
                        // 主要用于处理大数据流，比如一个1G大小的文件如果你直接传输肯定会撑暴jvm内存的;
                        // 增加之后就不用考虑这个问题了
                        pipeline.addLast(new ChunkedWriteHandler());
                        // HttpObjectAggregator 是完全的解析Http消息体请求用的
                        // 把多个消息转换为一个单一的完全FullHttpRequest或是FullHttpResponse，
                        // 原因是HTTP解码器会在每个HTTP消息中生成多个消息对象HttpRequest/HttpResponse,HttpContent,LastHttpContent
                        pipeline.addLast(new HttpObjectAggregator(64 * 1024));
                        // WebSocket数据压缩
                        pipeline.addLast(new WebSocketServerCompressionHandler());
                        // WebSocketServerProtocolHandler是配置websocket的监听地址/协议包长度限制
                        pipeline.addLast(new WebSocketServerProtocolHandler("/ws", null, true, 10 * 1024));

                        // 当连接在60秒内没有接收到消息时，就会触发一个 IdleStateEvent 事件，
                        // 此事件被 HeartbeatHandler 的 userEventTriggered 方法处理到
                        pipeline.addLast(
                                new IdleStateHandler(READ_IDLE_TIME_OUT, WRITE_IDLE_TIME_OUT, ALL_IDLE_TIME_OUT, TimeUnit.SECONDS));

                        // WebSocketServerHandler、TextWebSocketFrameHandler 是自定义逻辑处理器，
                        pipeline.addLast(new WebSocketTextHandler());
                    }
                });
        Channel ch = b.bind(port).syncUninterruptibly().channel();
        ch.closeFuture().syncUninterruptibly();

        // 返回与当前Java应用程序关联的运行时对象
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                SessionGroup.inst().shutdownGracefully();
                bossGroup.shutdownGracefully();
                workerGroup.shutdownGracefully();
            }
        });
    }
}

SocketSession:

package com.example.chat;

import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.AttributeKey;

import java.util.HashMap;
import java.util.Map;
import java.util.UUID;

public class SocketSession {

    public static final AttributeKey<SocketSession> SESSION_KEY = AttributeKey.valueOf("SESSION_KEY");

    /**
     * 用户实现服务端会话管理的核心
     */
// 通道
    private Channel channel;
    // 用户
    private User user;

    // session唯一标示
    private final String sessionId;

    private String group;

    /**
     * session中存储的session 变量属性值
     */
    private Map<String, Object> map = new HashMap<String, Object>();

    public SocketSession(Channel channel) {//注意传入参数channel。不同客户端会有不同channel
        this.channel = channel;
        this.sessionId = buildNewSessionId();
        channel.attr(SocketSession.SESSION_KEY).set(this);
    }

    // 反向导航
    public static SocketSession getSession(ChannelHandlerContext ctx) {//注意ctx，不同的客户端会有不同ctx
        Channel channel = ctx.channel();
        return channel.attr(SocketSession.SESSION_KEY).get();
    }

    // 反向导航
    public static SocketSession getSession(Channel channel) {
        return channel.attr(SocketSession.SESSION_KEY).get();
    }

    public String getId() {
        return sessionId;
    }

    private static String buildNewSessionId() {
        String uuid = UUID.randomUUID().toString();
        return uuid.replaceAll("-", "");
    }

    public synchronized void set(String key, Object value) {
        map.put(key, value);
    }

    public synchronized <T> T get(String key) {
        return (T) map.get(key);
    }

    public boolean isValid() {
        return getUser() != null ? true : false;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    public String getGroup() {
        return group;
    }

    public void setGroup(String group) {
        this.group = group;
    }

    public Channel getChannel() {
        return channel;
    }
}

WebSocketTextHandler:

package com.example.chat;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;

import java.util.HashMap;
import java.util.Map;

import static com.fasterxml.jackson.databind.type.LogicalType.Map;

public class WebSocketTextHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {


    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {

        // 是否握手成功，升级为 Websocket 协议
        if (evt == WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE) {
            // 握手成功，移除 HttpRequestHandler，因此将不会接收到任何消息
            // 并把握手成功的 Channel 加入到 ChannelGroup 中
            new SocketSession(ctx.channel());
        } else if (evt instanceof IdleStateEvent) {
            IdleStateEvent stateEvent = (IdleStateEvent) evt;
            if (stateEvent.state() == IdleState.READER_IDLE) {
                System.out.println("bb22");
            }
        } else {
            super.userEventTriggered(ctx, evt);
        }
    }

    @Override
    protected void messageReceived(ChannelHandlerContext channelHandlerContext, TextWebSocketFrame textWebSocketFrame) throws Exception {
        SocketSession session = SocketSession.getSession(channelHandlerContext);
        TypeToken<HashMap<String, String>> typeToken = new TypeToken<HashMap<String, String>>() {
        };

        Gson gson=new Gson();
        java.util.Map<String,String> map = gson.fromJson(textWebSocketFrame.text(), typeToken.getType());
        User user = null;
        switch (map.get("type")) {
            case "msg":
                Map<String, String> result = new HashMap<>();
                user = session.getUser();
                result.put("type", "msg");
                result.put("msg", map.get("msg"));
                result.put("sendUser", user.getNickname());
                SessionGroup.inst().sendToOthers(result, session);
                break;
            case "init":
                String room = map.get("room");
                session.setGroup(room);
                String nick = map.get("nick");
                user = new User(session.getId(), nick);
                session.setUser(user);
                SessionGroup.inst().addSession(session);
                break;
        }
    }
}

然后编写一个测试的html文件（桌面建一个就行）：

<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>群聊天室</title>
    <style type="text/css">
        body {
            margin-right:50px;
            margin-left:50px;
        }
        .ddois {
            position: fixed;
            left: 120px;
            bottom: 30px;
        }
    </style>
</head>
<body>
群名：<input type="text" id="room" name="group" placeholder="请输入群">
<br /><br />
昵称：<input type="text" id="nick" name="name" placeholder="请输入昵称">
<br /><br />
<button type="button" onclick="enter()">进入聊天群</button>
<br /><br />
<div id="message"></div>
<br /><br />
<div class="ddois">
    <textarea name="send" id="text" rows="10" cols="30" placeholder="输入发送消息"></textarea>
    <br /><br />
    <button type="button" onclick="send()">发送</button>
</div>
<script type="text/javascript">
    var webSocket;

    if (window.WebSocket) {
        webSocket = new WebSocket("ws://localhost:53134/ws");
    } else {
        alert("抱歉，您的浏览器不支持WebSocket协议!");
    }

    //连通之后的回调事件
    webSocket.onopen = function() {
        console.log("已经连通了websocket");
//                setMessageInnerHTML("已经连通了websocket");
    };
    //连接发生错误的回调方法
    webSocket.onerror = function(event){
        console.log("出错了");
//              setMessageInnerHTML("连接失败");
    };

    //连接关闭的回调方法
    webSocket.onclose = function(){
        console.log("连接已关闭...");

    }

    //接收到消息的回调方法
    webSocket.onmessage = function(event){
        console.log("bbdds");
        var data = JSON.parse(event.data)
        var msg = data.msg;
        var nick = data.sendUser;
        switch(data.type){
            case 'init':
                console.log("mmll");
                break;
            case 'msg':
                console.log("bblld");
                setMessageInnerHTML(nick+":  "+msg);
                break;
            default:
                break;
        }
    }
    function enter(){
        var map = new Map();
        var nick=document.getElementById('nick').value;
        var room=document.getElementById('room').value;
        map.set("type","init");
        map.set("nick",nick);
        console.log(room);
        map.set("room",room);
        var message = Map2Json(map);
        webSocket.send(message);
    }

    function send() {
        var msg = document.getElementById('text').value;
        var nick = document.getElementById('nick').value;
        console.log("1:"+msg);
        if (msg != null && msg != ""){
            var map = new Map();
            map.set("type","msg");
            map.set("msg",msg);
            var map2json=Map2Json(map);
            if (map2json.length < 8000){
                console.log("4:"+map2json);
                webSocket.send(map2json);
            }else {
                console.log("文本太长了，少写一点吧