安卓应用调用https://api.weixin.qq.com/card/invoice/reimburse/getinvoiceinfo?access_token={access_token}接口，提示"errcode":40001,"errmsg":"invalid credential, access_token is invalid or not latest hint: [JH0ZGA06814326]"。外部APP获取发票信息的access_token应该如何获取？