B4X

Refresh GMail SMTP OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an access token for sending email via GMail (SMTP). B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

'  See Get GMail SMTP Access Token 
'  for sample code showing how to obtain a GMail SMTP access token for desktop apps.

'  It is assumed we previously obtained an OAuth2 access token for GMail (one with a scope for sending email).

Dim jsonToken As ChilkatJsonObject
jsonToken.Initialize
success = jsonToken.LoadFile("qa_data/tokens/_gmailSmtp.json")
If success <> True Then
    Log("Failed to load _gmailSmtp.json")
    Return
End If


'  The access token JSON looks something like this:

'  	{ 
'  	 "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
'  	 "token_type": "Bearer",
'  	 "expires_in": 3600,
'  	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
'  	}
'  

Dim oauth2 As ChilkatOAuth2
oauth2.Initialize("oauth2")

oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

'  Replace these with actual values.
oauth2.ClientId = "GOOGLE-CLIENT-ID"
oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"

'  Get the "refresh_token"
oauth2.RefreshToken = jsonToken.StringOf("refresh_token")

'  Send the HTTP POST to refresh the access token..
success = oauth2.RefreshAccessToken
If success <> True Then
    Log(oauth2.LastErrorText)
    Return
End If


'  The response contains a new access token, but we must keep
'  our existing refresh token for when we need to refresh again in the future.
jsonToken.UpdateString("access_token", oauth2.AccessToken)

'  Save the new JSON access token response to a file.
Dim sbJson As ChilkatStringBuilder
sbJson.Initialize
jsonToken.EmitCompact = False
jsonToken.EmitSb(sbJson)
sbJson.WriteFile("qa_data/tokens/_gmailSmtp.json", "utf-8", False)

Log("OAuth2 authorization granted!")
Log("New Access Token = " & oauth2.AccessToken)