(Java) GMail IMAP Authentication using OAuth2 Access Token

Demonstrates how to do IMAP OAuth2 authentication for GMail (or any other IMAP mail server supporting OAuth2 authentication). This example assumes an OAuth2 access token was previously obtained.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // See Get GMail IMAP OAuth2 Access Token for Desktop App 
    // for sample code showing how to obtain a GMail IMAP read/write access token.

    // In this example, our access token was previously saved to the following file which contains JSON like this:
    // 	{
    // 	 "access_token": "ya39.Ci-XA_C5bGgRDC3UaD-h0_NeL-DVIQnI2gHtBBBHkZzrwlARkwX6R3O0PCDEzRlfaQ",
    // 	 "token_type": "Bearer",
    // 	 "expires_in": 3600,
    // 	 "refresh_token": "1/r_2c_7jddspcdfesrrfKqfXtqo08D6Q-gUU0DsdfVMsx0c"
    // 	}
    // 
    CkJsonObject json = new CkJsonObject();
    boolean success = json.LoadFile("qa_data/tokens/_gmailFullAccess.json");
    if (success != true) {
        System.out.println("Failed to load GMail access token file.");
        return;
        }

    String accessToken = json.stringOf("access_token");

    // Do OAuth2 authentication by using the access token as the password in the Login method below...
    CkImap imap = new CkImap();

    imap.put_Ssl(true);
    imap.put_Port(993);

    // Connect to the GMail IMAP server.
    success = imap.Connect("imap.gmail.com");
    if (success != true) {
        System.out.println(imap.lastErrorText());
        return;
        }

    // Indicate that XOAUTH2 authentication is to be used:
    imap.put_AuthMethod("XOAUTH2");

    // Login
    // Use the email address of the GMail account that granted authorization.
    success = imap.Login("user@gmail.com",accessToken);
    if (success != true) {
        System.out.println(imap.lastErrorText());
        }
    else {
        System.out.println("Successfully authenticated with GMail IMAP using XOAUTH2!");
        }
  }
}