(Android™) Facebook OAuth2 Access Token

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Note: This example requires Chilkat v10.1.2 or greater.

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// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // To further clarify, see OAuth 2.0 Authorization Flow

    CkOAuth2 oauth2 = new CkOAuth2();

    // This should match the Site URL configured for your Facebook APP, such as "http://localhost:3017/"
    oauth2.put_ListenPort(3017);

    oauth2.put_AuthorizationEndpoint("https://www.facebook.com/dialog/oauth");
    oauth2.put_TokenEndpoint("https://graph.facebook.com/oauth/access_token");

    // Replace this with your actual App ID
    oauth2.put_ClientId("APP_ID");

    // Set the Scope to a comma-separated list of permissions the app wishes to request.
    // See https://developers.facebook.com/docs/facebook-login/permissions/ for a full list of permissions.
    oauth2.put_Scope("public_profile,user_friends,email,user_posts,user_likes,user_photos");

    // This is for Require Proof Key for Code Exchange (PKCE)
    // See OAuth2 PKCE Explained
    oauth2.put_CodeChallenge(true);
    oauth2.put_CodeChallengeMethod("S256");

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    String url = oauth2.startAuth();
    if (oauth2.get_LastMethodSuccess() != true) {
        Log.i(TAG, oauth2.lastErrorText());
        return;
        }

    Log.i(TAG, "url = " + url);

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    boolean success = oauth2.LaunchBrowser(url);
    if (success == false) {
        Log.i(TAG, oauth2.lastErrorText());
        return;
        }

    // Wait for the user to approve or deny authorization in the browser.
    int numMsWaited = 0;
    while ((numMsWaited < 90000) and (oauth2.get_AuthFlowState() < 3)) {
        oauth2.SleepMs(100);
        numMsWaited = numMsWaited + 100;
        }

    // If the browser does not respond within the specified time, AuthFlowState will be:
    // 
    // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
    // 2: Waiting for Final Response – The thread is awaiting the final access token response.
    // In either case, cancel the background task initiated by StartAuth.

    if (oauth2.get_AuthFlowState() < 3) {
        oauth2.Cancel();
        Log.i(TAG, "No response from the browser!");
        return;
        }

    // Check AuthFlowState to determine if authorization was granted, denied, or failed:
    // 
    // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
    // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
    // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

    if (oauth2.get_AuthFlowState() == 5) {
        Log.i(TAG, "OAuth2 failed to complete.");
        Log.i(TAG, oauth2.failureInfo());
        return;
        }

    if (oauth2.get_AuthFlowState() == 4) {
        Log.i(TAG, "OAuth2 authorization was denied.");
        Log.i(TAG, oauth2.accessTokenResponse());
        return;
        }

    if (oauth2.get_AuthFlowState() != 3) {
        Log.i(TAG, "Unexpected AuthFlowState:" + String.valueOf(oauth2.get_AuthFlowState()));
        return;
        }

    Log.i(TAG, "OAuth2 authorization granted!");
    Log.i(TAG, "Access Token = " + oauth2.accessToken());

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}