在app.js中定义onlaunch如下：

onLaunch: function (res) {
    this.shareTicket = res.shareTicket;


    wx.getShareInfo({
      shareTicket: this.shareTicket,
      success: function (res) {
        console.log("success")
      }, 
      fail: function(res) {
        console.log(res)
      }
    })
}