how to collect contacts from different accounts

so i was wondering this: for example: when you subscribe to Facebook you have the option to invite your friend开发者_如何学JAVAs from gmail(if you have a gmail account), so you would enter your gmail login and password and facebook would grab all your contacts from gmail, so i was wondering how this is done? is there an API from Gmail or from Hotmail that permits to program this? thanks

These sites don't use an all-encompassing API, they take your login you provide and from their side login to Google (for example) as you and scrape it for your contact info.

This is why you should also be very careful about who you trust with that login information.

yes .There r different API's for all of these.you can download them by simply typing contact fetcher script in Google or something like this. They r free.

refer link https://sourceforge.net/projects/contactgrabber

There might not be an API specifically for it, but it's still pretty easy. I did something similar with PHP, using CURL to log in to a website and download reports automatically.

edit: You should be aware that some sites won't like that you do it, and might sue you for it. Always get a permission from the site owner before you try it.