config/config.default.js

  exports.io = {
    init: {},
    namespace: {
      '/': {       //对应router.js里的 of('/')
        connectionMiddleware: [ 'auth' ],    //对应io/middleware/auth
        packetMiddleware: [ 'filter' ],
      },
    },
  };

 config/plugin.js

exports.io = {
  enable: true,
  package: 'egg-socket.io',
};

 router.js

    io.of('/').route('chat', io.controller.chat.index);
    io.of('/').route('message', io.controller.chat.message);
    io.of('/').route('user:online', io.controller.chat.online);

 app/io

app/io/middleware/auth.js

/**
 * Created by bear on 2018/2/12.
 */
const PREFIX = 'room';  //定义房间号

module.exports = app => {
  return async (ctx, next) => {
    const { app, socket, logger, helper } = ctx;
    const id = socket.id;
    const nsp = app.io.of('/');
    const query = socket.handshake.query;

    // 用户信息
    const { room, userId } = query;  //获取socket链接传过来的参数
    const rooms = [ room ];

    console.log(room, userId);

    const tick = (id, msg) => {
      logger.debug('#tick', id, msg);
      // 踢出用户前发送消息
      socket.emit(id, helper.parseMsg('deny', msg));
      // 调用 adapter 方法踢出用户，客户端触发 disconnect 事件
      nsp.adapter.remoteDisconnect(id, true, err => {
        logger.error(err);
      });
    };
    // 检查房间是否存在，不存在则踢出用户
    // 备注：此处 app.redis 与插件无关，可用其他存储代替
   
    const hasRoom = await app.redis.get(`${PREFIX}:${room}`);
    console.log(hasRoom,`${PREFIX}:${room}`)

    // if (!hasRoom) {
    //   tick(id, {
    //     type: 'deleted',
    //     message: 'deleted, room has been deleted.',
    //   });
    //   return;
    // }

    // 用户加入
    logger.debug('#join', room);
    socket.join(room);

    // 在线列表
    nsp.adapter.clients(rooms, (err, clients) => {
      // 更新在线用户列表
      nsp.to(room).emit('online', {
        clients,
        action: 'join',
        target: 'participator',
        message: `User(${id}) joined.`,
      });
      console.log(123,clients)
    });
    // socket.emit('connect', 'packet received!');
    
    await next();
    console.log('disconnect!');

  };
};

 app/io/middleware/filter.js

module.exports = (app) => {
    return async (ctx, next) => {
        // console.log(ctx.packet);
        await next();
        // console.log('packet response!');
    };
};

 app/io/controller/chat.js

/**
 * Created by bear on 2018/2/12.
 */
module.exports = app => {
  class chatController extends app.Controller {
    async index() {
      this.ctx.socket.emit('res', 'test');
    }
    async message() {   //方法通过 客户端 this.emit（'message',{}）//触发
      this.ctx.socket.emit('message', 'test');
      const params = this.ctx.args[0];
     // this.ctx.service.message.sendPeerMessage(params);
      console.log(2,params);
    }


    async online() {// modelMessage.sendOfflineMessage(socket, data.userId);
    }
  }
  return chatController;
};