gcalendar_controller.rb

require 'google/api_client'

class GcalendarController < ApplicationController

  before_filter :setup

  def events

    # 取得 calendar API的service
    @calendar = @client.discovered_api('calendar', 'v3')
    
    # 调用取得calendar 一览接口
    @calendarlist = @client.execute(:api_method => @calendar.calendar_list.list,
                              :authorization => @client.authorization)

    # 调用取得某一calendar里面某一天的events
    # 注意，日期格式要iso8601，且要注意时区信息
    day = Time.now
    @time_min = Time.local(day.year, day.month, day.day, 0,0,0).iso8601
    @time_max = Time.local(day.year, day.month, day.day, 23,59,59).iso8601

    @events = @client.execute(:api_method => @calendar.events.list,
                              :parameters => {'calendarId' => 'primary',
                                "timeMin" => @time_min,
                                "timeMax" => @time_max
                                },
                              :authorization => @client.authorization)

  end

  def login
      # login画面，提供了一个指向Google的认证链接，即下面这个网址
      # @client.authorization.authorization_uri
      @redirect_uri = @client.authorization.authorization_uri
  end

  # 每个action执行前设置token等信息
  def setup
    @client = Google::APIClient.new
    @client.authorization.client_id = '........'
    @client.authorization.client_secret = '........'
    @client.authorization.scope = 'https://www.googleapis.com/auth/calendar'
    @client.authorization.redirect_uri = 'http://localhost:3000/gcalendar/callback'

    # got access_token
    # TODO: need more conditions
    access_token = session[:access_token]
    unless access_token.nil?
      # 如果已经授权过了，设置token信息。
      @client.authorization.access_token  = session[:access_token]
      @client.authorization.refresh_token = session[:refresh_token]
      @client.authorization.expires_in    = session[:expires_in]
      @client.authorization.issued_at     = session[:issued_at]
    end
  end

  # Google API 服务器授权后的回调接口
  def callback
    # 设置code，从Google 服务器返回的
    @client.authorization.code = params[:code] if params[:code]
    # 取得access token等信息
    @client.authorization.fetch_access_token!

    # 将token相关信息保存到session
    session[:access_token] = @client.authorization.access_token
    session[:refresh_token] = @client.authorization.refresh_token
    session[:expires_in] = @client.authorization.expires_in
    session[:issued_at] = @client.authorization.issued_at

    redirect_to :action => 'events'
  end

end