I have a website where is discussion is happening among some people with valid gmail ids. If one of them in the discussion clicks on the google hangout button, I need to start a hangout with the list of users in the discussion invited already i.e. I need to avoid the Add Participant popup that comes up when the hangout app is opened. Is there a way to do this? I explored the documentation and I couldn't find any API to invite a participant.
To the best of my knowledge (and more than willing to be corrected), there isn't a way to trigger a hangout with a set of participants. There is a bit of a hack using the calendar API though - you could create a calendar entry in a calendar set to automatically create hangouts, and invite everyone that way. I had an old blog post on it: http://www.riskcompletefailure.com/2012/11/programmatically-scheduling-hangouts.html
I believe this is new capability since the question was asked, but it is now possible to create a hangout button which starts a hangout with a list of users invited (based upon G+ Profile Id, G+ Circle Id, or Email Address).
See details at https://developers.google.com/+/hangouts/button#invite_parameters.
Note: The list is only a suggestion to the user that starts the Hangout. Before the Hangout begins, that user will be able to skip the invite or change the list of people.
来源：https://stackoverflow.com/questions/18010875/starting-a-hangout-with-a-list-of-users-invited