(Java) POP3 GMail XOAUTH2 Authentication

Demonstrates using OAuth2 authentication with pop.gmail.com.

Note: This example requires Chilkat v9.5.0.83 or greater.

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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.

    CkMailMan mailman = new CkMailMan();

    mailman.put_MailHost("pop.gmail.com");
    mailman.put_MailPort(995);
    mailman.put_PopSsl(true);

    mailman.put_PopUsername("my_account@gmail.com");

    // If using OAuth2 authentication, leave the password empty.
    mailman.put_PopPassword("");

    // Load our previously obtained OAuth2 access token.
    // See Getting a GMail POP3 OAuth2 Access Token
    CkJsonObject jsonToken = new CkJsonObject();
    boolean success = jsonToken.LoadFile("qa_data/tokens/gmail_pop3.json");
    if (success == false) {
        System.out.println(jsonToken.lastErrorText());
        return;
        }

    mailman.put_OAuth2AccessToken(jsonToken.stringOf("access_token"));

    // Make the TLS connection to the POP3 server.
    success = mailman.Pop3Connect();
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Authenticate..
    success = mailman.Pop3Authenticate();
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Find out how many emails are on the server..
    int numEmails = mailman.CheckMail();
    if (numEmails < 0) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    // Examine the POP3 session log:
    System.out.println(mailman.pop3SessionLog());

    // The POP3 session log will look something like this:

    // **** Connected to pop.gmail.com:995
    // < +OK Gpop ready for requests from 87.9.200.42 l16mb86351205iok
    // > AUTH XOAUTH2 dXNlcj1....VaMDJFAQE=
    // < +OK Welcome.
    // > STAT
    // < +OK 301 1627357
    // 
    // -- Finished.

    // End the POP3 session and close the connection to the GMail server.
    success = mailman.Pop3EndSession();
    if (success != true) {
        System.out.println(mailman.lastErrorText());
        return;
        }

    System.out.println("-- Finished.");
  }
}