序言：因工作项目需要使用到推送功能，且与前端Socket.IO框架对接，因此使用了Netty-SocketIO。Netty-SocketIO顾名思义是基于Netty的SocketIO，底层是基于Netty。有关SocketIO的相关API与官网提供的NodeJS版本API相似，相关配置与Netty相关配置相似。以下代码在SpringBoot项目中书写，解释都在代码里，直接看代码吧。

• netty-socketio maven依赖

<dependency>
    <groupId>com.corundumstudio.socketio</groupId>
    <artifactId>netty-socketio</artifactId>
    <version>1.7.7</version>
</dependency>

• application.properties相关配置

#============================================================================
# netty socket io setting
#============================================================================
# host在本地测试可以设置为localhost或者本机IP，在Linux服务器跑可换成服务器IP
socketio.host=localhost
socketio.port=9099
# 设置最大每帧处理数据的长度，防止他人利用大数据来攻击服务器
socketio.maxFramePayloadLength=1048576
# 设置http交互最大内容长度
socketio.maxHttpContentLength=1048576
# socket连接数大小（如只监听一个端口boss线程组为1即可）
socketio.bossCount=1
socketio.workCount=100
socketio.allowCustomRequests=true
# 协议升级超时时间（毫秒），默认10秒。HTTP握手升级为ws协议超时时间
socketio.upgradeTimeout=1000000
# Ping消息超时时间（毫秒），默认60秒，这个时间间隔内没有接收到心跳消息就会发送超时事件
socketio.pingTimeout=6000000
# Ping消息间隔（毫秒），默认25秒。客户端向服务器发送一条心跳消息间隔
socketio.pingInterval=25000

• SocketIOConfig.java配置文件相关配置

import com.corundumstudio.socketio.SocketConfig;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.corundumstudio.socketio.SocketIOServer;

@Configuration
public class SocketIOConfig {

    @Value("${socketio.host}")
    private String host;

    @Value("${socketio.port}")
    private Integer port;

    @Value("${socketio.bossCount}")
    private int bossCount;

    @Value("${socketio.workCount}")
    private int workCount;

    @Value("${socketio.allowCustomRequests}")
    private boolean allowCustomRequests;

    @Value("${socketio.upgradeTimeout}")
    private int upgradeTimeout;

    @Value("${socketio.pingTimeout}")
    private int pingTimeout;

    @Value("${socketio.pingInterval}")
    private int pingInterval;

    /**
     * 以下配置在上面的application.properties中已经注明
     * @return
     */
    @Bean
    public SocketIOServer socketIOServer() {
        SocketConfig socketConfig = new SocketConfig();
        socketConfig.setTcpNoDelay(true);
        socketConfig.setSoLinger(0);
        com.corundumstudio.socketio.Configuration config = new com.corundumstudio.socketio.Configuration();
        config.setSocketConfig(socketConfig);
        config.setHostname(host);
        config.setPort(port);
        config.setBossThreads(bossCount);
        config.setWorkerThreads(workCount);
        config.setAllowCustomRequests(allowCustomRequests);
        config.setUpgradeTimeout(upgradeTimeout);
        config.setPingTimeout(pingTimeout);
        config.setPingInterval(pingInterval);
        return new SocketIOServer(config);
    }
}

以下就是提供一个SocketIOService接口，供其他地方需要使用时调用。

public interface SocketIOService {

    //推送的事件
    public static final String PUSH_EVENT = "push_event";
    
    // 启动服务
    void start() throws Exception;
    
    // 停止服务
    void stop();
    
    // 推送信息
    void pushMessageToUser(PushMessage pushMessage);
}

• SocketIOServiceImpl.java接口实现类

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

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.corundumstudio.socketio.SocketIOClient;
import com.corundumstudio.socketio.SocketIOServer;

@Service(value = "socketIOService")
public class SocketIOServiceImpl implements SocketIOService {

    // 用来存已连接的客户端
    private static Map<String, SocketIOClient> clientMap = new ConcurrentHashMap<>();

    @Autowired
    private SocketIOServer socketIOServer;

    /**
     * Spring IoC容器创建之后，在加载SocketIOServiceImpl Bean之后启动
     * @throws Exception
     */
    @PostConstruct
    private void autoStartup() throws Exception {
        start();
    }

    /**
     * Spring IoC容器在销毁SocketIOServiceImpl Bean之前关闭,避免重启项目服务端口占用问题
     * @throws Exception
     */
    @PreDestroy
    private void autoStop() throws Exception  {
        stop();
    }
    
    @Override
    public void start() {
        // 监听客户端连接
        socketIOServer.addConnectListener(client -> {
            String loginUserNum = getParamsByClient(client);
            if (loginUserNum != null) {
                clientMap.put(loginUserNum, client);
            }
        });

        // 监听客户端断开连接
        socketIOServer.addDisconnectListener(client -> {
            String loginUserNum = getParamsByClient(client);
            if (loginUserNum != null) {
                clientMap.remove(loginUserNum);
                client.disconnect();
            }
        });

        // 处理自定义的事件，与连接监听类似
        socketIOServer.addEventListener(PUSH_EVENT, PushMessage.class, (client, data, ackSender) -> {
            // TODO do something
        });
        socketIOServer.start();
    }

    @Override
    public void stop() {
        if (socketIOServer != null) {
            socketIOServer.stop();
            socketIOServer = null;
        }
    }

    @Override
    public void pushMessageToUser(PushMessage pushMessage) {
        String loginUserNum = pushMessage.getLoginUserNum();
        if (StringUtils.isNotBlank(loginUserNum)) {
            SocketIOClient client = clientMap.get(loginUserNum);
            if (client != null)
                client.sendEvent(PUSH_EVENT, pushMessage);
        }
    }

    /**
     * 此方法为获取client连接中的参数，可根据需求更改
     * @param client
     * @return
     */
    private String getParamsByClient(SocketIOClient client) {
        // 从请求的连接中拿出参数（这里的loginUserNum必须是唯一标识）
        Map<String, List<String>> params = client.getHandshakeData().getUrlParams();
        List<String> list = params.get("loginUserNum");
        if (list != null && list.size() > 0) {
            return list.get(0);
        }
        return null;
    }
}

• PushMessage 实体类：推送到客户端的消息体

@Data
@ToString
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class PushMessage {
    @ApiModelProperty(value = "登录用户编号")
    private Integer loginUserNum;

    @ApiModelProperty(value = "推送内容")
    private String content;

    // Other Detail Property...
}

• 前端相关测试页面编写

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>NETTY SOCKET.IO DEMO</title>
    <base>
    <script src="../static/js/jquery-1.11.1.min.js"></script>
    <script src="../static/js/socket.io.js"></script>
    <style>
        body {
            padding: 20px;
        }
        #console {
            height: 450px;
            overflow: auto;
        }
        .username-msg {
            color: orange;
        }
        .connect-msg {
            color: green;
        }
        .disconnect-msg {
            color: red;
        }
    </style>
</head>

<body>
    <div id="console" class="well"></div>
</body>
<script type="text/javascript">
    var socket;
    connect();

    function connect() {
        var loginUserNum = '88';
        var opts = {
            query: 'loginUserNum=' + loginUserNum
        };
        socket = io.connect('http://localhost:9099', opts);
        socket.on('connect', function () {
            console.log("连接成功");
            serverOutput('<span class="connect-msg">连接成功</span>');
        });
        socket.on('push_event', function (data) {
            output('<span class="username-msg">' + data + ' </span>');
            console.log(data);
        });

        socket.on('disconnect', function () {
            serverOutput('<span class="disconnect-msg">' + '已下线! </span>');
        });
    }
    
    function output(message) {
        var element = $("<div>" + " " + message + "</div>");
        $('#console').prepend(element);
    }

    function serverOutput(message) {
        var element = $("<div>" + message + "</div>");
        $('#console').prepend(element);
    }
</script>
</html>

到此，以上就是netty-socketio与SpringBoot项目整合以及使用。如有错误，谢谢指出。