How do i get end point url?

Question

I have to connect two different sales force org am getting error for 400 and 302 and bad request. Where do I get refresh token, Please can you give suggestion what correction should I do?

httprequest hreq=new httprequest(); //string
refresh_url='https://login.salesforce.com/services/oauth2/token?grant_type=refresh_token&client_id=3MVG9Y6d_Btp4xp7AyV8b3ouuXI_CkGlTRIJLDmriyEpT59eoFmWPZBwjZmoI8Raq3cRrYzFZ.Oa9ZpBayp87&client_secret=3678419209862860540&refresh_token=0Ak900000GcOb09';
string
refresh_url='https://login.salesforce.com/services/oauth2/authorize?response_type=token+id_token&client_id=3MVG9Y6d_Btp4xp7AyV8b3ouuXI_CkGlTRIJLDmriyEpT59eoFmWPZBwjZmoI8Raq3cRrYzFZ.Oa9ZpBayp87&redirect_uri=https://login.salesforce.com/services/oauth2/success';
    system.debug('------------refresh_url------------'+refresh_url); hreq.Setendpoint(refresh_url); hreq.setmethod('POST');
 hreq.setHeader('Accept',
 'application/application/x-www-form-urlencoded;charset=UTF-8');
 hreq.setHeader('Host','ap1.salesforce.com'); http htp=new http();
 httpResponse res=htp.send(hreq); 

 System.debug('-----------------FutureRefreshToken_ID------------------'
 +res.getBody()); //string result=readXMLResponseOfFutureAccessToken(res.getBody());

Answer 1

Both Webserver flow & User Agent Flow provides you with a response with Refresh token which can be used in your further calls.

https://help.salesforce.com/HTViewHelpDoc?id=remoteaccess_oauth_user_agent_flow.htm&language=en_US