Java Example using Apache's OLTU OAuth2 library

gistfile1.java

/// GENERAL METHODS FOR OAUTH'ING
///  using the Apache Oltu library
/// https://cwiki.apache.org/confluence/display/OLTU/Index

    public String getAuthUrl() {

        OAuthClientRequest request = null;
        try {
            request = OAuthClientRequest
                    .authorizationLocation("https://www.hackerschool.com/oauth/authorize")
                    .setClientId(Constants.CLIENT_ID)
                    .setResponseType("code")
                    .setRedirectURI(Constants.REDIRECT_URI)
                    .buildQueryMessage();
        }
        catch (OAuthSystemException e) {
            Log.e(TAG, "exception loading oauth ", e);
        }

        return request.getLocationUri();
    }

     // Note: should be run on background thread
     public void getAccessToken(final String accessCode) {

        try {
            OAuthClientRequest request = OAuthClientRequest
                    .tokenLocation("https://www.hackerschool.com/oauth/token")
                    .setClientId(Constants.CLIENT_ID)
                    .setClientSecret(Constants.CLIENT_SECRET)
                    .setRedirectURI(Constants.REDIRECT_URI)
                    .setGrantType(GrantType.AUTHORIZATION_CODE)
                    .setCode(accessCode)
                    .buildBodyMessage();
                OAuthJSONAccessTokenResponse response = mClient.accessToken(mRequest);
                mAccessToken = response.getAccessToken();
        }
        catch (OAuthSystemException e) {
            Log.e(TAG, "exception loading oauth ", e);
        }
    }

    // NOTE: Should be run on background thread
    public void makeARequest() throws OAuthSystemException, OAuthProblemException {
        OAuthClientRequest bearerRequest = new OAuthBearerClientRequest("https://www.hackerschool.com/api/v1/people/me")
                .setAccessToken(mAccessToken)
                .buildQueryMessage();

        OAuthResourceResponse response = mClient.resource(bearerRequest, OAuth.HttpMethod.GET, OAuthResourceResponse.class);

        response.getBody();
        response.getResponseCode();
    }


/// ANDROID IMPLEMENTATION (partially complete) FOR USING A WEBVIEW
 private void setupWebView() {
        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(final WebView view, final String url) {
                if (url.startsWith(Constants.REDIRECT_URI)) {
                    Uri uri = Uri.parse(url);
                    if (uri.getQueryParameter("code") != null) {
                        String code = uri.getQueryParameter("code");
                        getAccessToken(code);
                        return true;
                    }
                    else if (uri.getQueryParameter("error") != null) {
                        String message = uri.getQueryParameter("error_message");
                        Toast.makeText(LoginActivity.this, message, Toast.LENGTH_LONG).show();
                    }
                }
                return super.shouldOverrideUrlLoading(view, url);
            }

        });
        mWebView.loadUrl(getAuthUrl());
    }