我正在尝试使用kotlin和V3API为google日历设置推送通知。
这是我的类，包含用于crud操作的函数和事件：

import com.google.api.client.auth.oauth2.Credential
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport
import com.google.api.client.http.javanet.NetHttpTransport
import com.google.api.client.json.JsonFactory
import com.google.api.client.json.jackson2.JacksonFactory
import com.google.api.client.util.DateTime
import com.google.api.client.util.store.FileDataStoreFactory
import com.google.api.services.calendar.Calendar
import com.google.api.services.calendar.CalendarScopes
import com.google.api.services.calendar.model.*
import java.io.*

class CalendarAPI {
    private val appName = "Calendar"
    private val jsonFactory: JsonFactory = JacksonFactory.getDefaultInstance()

    /**
     * Global instance of the scopes required by this quickstart.
     * If modifying these scopes, delete your previously saved tokens/ folder.
     */
    private val scopes = listOf(CalendarScopes.CALENDAR)
    private val credentialsPath = "/Credentials.json"

    // Build a new authorized API client service.
    private val httpTransport = GoogleNetHttpTransport.newTrustedTransport()
    val service: Calendar =
        Calendar.Builder(httpTransport, jsonFactory, getCredentials(httpTransport))
            .setApplicationName(appName)
            .build()

    // List the next 10 events from the primary calendar.
    fun getNext10Events(now: DateTime): Events {
        return service.events().list("primary")
            .setMaxResults(10)
            .setTimeMin(now)
            .setOrderBy("startTime")
            .setSingleEvents(true)
            .execute()
    }

    fun printEvents(events: Events) {
        val items = events.items
        if (items.isEmpty()) {
            println("No events found!")
        } else {
            for (event in items) {
                val start = if (event.start.dateTime == null)
                    event.start.date else event.start.dateTime

                val end = if (event.end.dateTime == null)
                    event.end.date else event.end.dateTime

                println("${event.summary} starts:($start), ends:($end)")
            }
        }
    }

    fun deleteEvents(calendarId: String, events: Events, range: List<Int>) {
        for (i in range) {
            try {
                service.events().delete(calendarId, events.items[i].id).execute()
            } catch (e: IndexOutOfBoundsException) {
                throw Exception("Deletion of events failed! Probably index out of bounds.")
            }
        }
    }

    fun deleteAllEvents(calendarId: String) {
        service.calendars().clear(calendarId).execute()
    }

    fun createEvent(
        calendarId: String,
        startDateTime: DateTime,
        endDateTime: DateTime,
        summary: String? = null,
        location: String? = null,
        description: String? = null,
        recurrence: List<String> = emptyList(),
        attendees: List<EventAttendee> = emptyList(),
        reminder: List<EventReminder> = emptyList(),
        timeZone: String = "(GMT+03:00) Eastern European Time - Sofia",
        sendEmailNotification: Boolean = false
    ): Event {
        val event: Event = Event()
            .setSummary(summary)
            .setLocation(location)
            .setDescription(description)

        event.recurrence = recurrence

        event.attendees = attendees

        val reminders: Event.Reminders = Event.Reminders()
            .setUseDefault(false)
            .setOverrides(reminder)
        event.reminders = reminders

        val start = EventDateTime()
            .setDateTime(startDateTime)
            .setTimeZone(timeZone)
        event.start = start

        val end = EventDateTime()
            .setDateTime(endDateTime)
            .setTimeZone("America/Los_Angeles")
        event.end = end

        service.events().insert(calendarId, event).setSendNotifications(sendEmailNotification).execute()
        return event
    }

    fun updateEvent(
        event: Event,
        startDateTime: DateTime? = null,
        endDateTime: DateTime? = null,
        summary: String? = null,
        location: String? = null,
        description: String? = null,
        recurrence: List<String> = emptyList(),
        attendees: List<EventAttendee> = emptyList(),
        reminder: List<EventReminder> = emptyList(),
        timeZone: String = "(GMT+03:00) Eastern European Time - Sofia",
        sendEmailNotification: Boolean = false
    ) {
        if (startDateTime != null) {
            event.start = EventDateTime().setDateTime(startDateTime).setTimeZone(timeZone)
        }
        if (endDateTime != null) {
            event.end = EventDateTime().setDateTime(endDateTime).setTimeZone(timeZone)
        }
        event.summary = summary
        event.location = location
        event.description = description
        event.recurrence = recurrence
        event.attendees = attendees
        val reminders: Event.Reminders = Event.Reminders()
            .setUseDefault(false)
            .setOverrides(reminder)
        event.reminders = reminders
        service.events().update("primary", event.id, event).setSendNotifications(sendEmailNotification).execute()
    }

    fun addAttendeesToEvent(event: Event, attendees: List<EventAttendee>, sendEmailNotification: Boolean = false){
        event.attendees.addAll(attendees)
        service.events().update("primary", event.id, event).setSendNotifications(sendEmailNotification).execute()
    }

    /**
     * Creates an authorized Credential object.
     * @param HTTP_TRANSPORT The network HTTP Transport.
     * @return An authorized Credential object.
     * @throws IOException If the credentials.json file cannot be found.
     */
    private fun getCredentials(HTTP_TRANSPORT: NetHttpTransport): Credential {
        // Load client secrets.
        val inputStream: InputStream =
            CalendarAPI::class.java.getResourceAsStream(credentialsPath)
                ?: throw FileNotFoundException("Resource not found: $credentialsPath")

        val clientSecrets = GoogleClientSecrets.load(
            jsonFactory,
            InputStreamReader(inputStream)
        )

        // Build flow and trigger user authorization request.
        val flow = GoogleAuthorizationCodeFlow.Builder(
            HTTP_TRANSPORT,
            jsonFactory,
            clientSecrets,
            scopes
        )
            .setDataStoreFactory(FileDataStoreFactory(File("token")))
            .setAccessType("offline")
            .build()
        val receiver = LocalServerReceiver.Builder().setPort(8888).build()
        return AuthorizationCodeInstalledApp(flow, receiver).authorize("user")
    }
}

这是我的主要文件：

package com.example.appolicacalendar

import com.google.api.client.util.DateTime
import com.google.api.services.calendar.model.Channel

fun main() {
    val calendar = CalendarAPI()

    val channel = Channel()
//    channel.address = "forChannel"
    channel.token = "forChannel"
    val param = calendar.service.events().watch("primary", channel)

    println("Upcoming events:")
    val events = calendar
        .getNext10Events(DateTime(System.currentTimeMillis()))
    calendar.printEvents(events)

//    calendar.deleteEvents("primary", events, arrayListOf(0))
    calendar.deleteAllEvents("primary")

    println("\nNew events:")
    val event = calendar.createEvent(
        summary = "CalendarEvent",
        calendarId = "primary",
        startDateTime = DateTime("2021-07-08T14:00:00.000+03:00"),
        endDateTime = DateTime("2021-07-08T15:00:00.000+03:00")
    )

//    calendar.updateEvent(event, summary = "CalendarEvent")
    calendar.printEvents(calendar.getNext10Events(DateTime(System.currentTimeMillis())))
}

我看到watch方法的一个参数是com.google.api.services.calendar.model.channel，正如您所看到的，我已经创建了它，但是idk如何使用它。
我的目标是记录并查看插入/更新/删除操作何时发生更改。