Question

I am trying to generate a OAUTH signature from flicker.com. I had obtained the source code from:

Absolute minimum code to get a valid oauth_signature populated in Java or Groovy?

But when I am trying to execute it I am getting “The Constructor Base64() is not visible error”.

My class is:

public class MainActivity extends Activity {

    Button login;

    //---------------------------------------------



     static String key = "key";
     static String secret = "secret";

     static final String HMAC_SHA1 = "HmacSHA1";

     static final String ENC = "UTF-8";

      static Base64 base64 = new Base64();



     @SuppressWarnings("static-access")
    private static String getSignature(String url, String params)
             throws UnsupportedEncodingException, NoSuchAlgorithmException,
             InvalidKeyException {
         /**
          * base has three parts, they are connected by "&": 1) protocol 2) URL
          * (need to be URLEncoded) 3) Parameter List (need to be URLEncoded).
          */
         StringBuilder base = new StringBuilder();
         base.append("GET&");
         base.append(url);
         base.append("&");
         base.append(params);
         System.out.println("Stirng for oauth_signature generation:" + base);
         // yea, don't ask me why, it is needed to append a "&" to the end of
         // secret key.
         byte[] keyBytes = (secret + "&").getBytes(ENC);

         SecretKey key = new SecretKeySpec(keyBytes, HMAC_SHA1);

         Mac mac = Mac.getInstance(HMAC_SHA1);
         mac.init(key);

         // encode it, base64 it, change it to string and return.
         return new String(base64.encode(mac.doFinal(base.toString().getBytes(
                 ENC)), 0, 0, 0), ENC).trim();
     }








    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        login=(Button)findViewById(R.id.login_button);
        login.setOnClickListener(new OnClickListener() {

            public void onClick(View v)  {

 HttpClient httpclient = new DefaultHttpClient();
            List<NameValuePair> qparams = new ArrayList<NameValuePair>();
            // These params should ordered in key
            qparams.add(new BasicNameValuePair("oauth_callback", "oob"));
            qparams.add(new BasicNameValuePair("oauth_consumer_key", key));
            qparams.add(new BasicNameValuePair("oauth_nonce", ""
                    + (int) (Math.random() * 100000000)));
            qparams.add(new BasicNameValuePair("oauth_signature_method",
                    "HMAC-SHA1"));
            qparams.add(new BasicNameValuePair("oauth_timestamp", ""
                    + (System.currentTimeMillis() / 1000)));
            qparams.add(new BasicNameValuePair("oauth_version", "1.0"));

            // generate the oauth_signature
            String signature = getSignature(URLEncoder.encode(
                    "http://www.flickr.com/services/oauth/request_token", ENC),
                    URLEncoder.encode(URLEncodedUtils.format(qparams, ENC), ENC));

            // add it to params list
            qparams.add(new BasicNameValuePair("oauth_signature", signature));

            // generate URI which lead to access_token and token_secret.
            URI uri = URIUtils.createURI("http", "www.flickr.com", -1,
                    "/services/oauth/request_token",
                    URLEncodedUtils.format(qparams, ENC), null);

            System.out.println("Get Token and Token Secrect from:"
                    + uri.toString());

            HttpGet httpget = new HttpGet(uri);
            // output the response content.
            System.out.println("oken and Token Secrect:");

            HttpResponse response = httpclient.execute(httpget);
            HttpEntity entity = response.getEntity();
            if (entity != null) {
                InputStream instream = entity.getContent();
                int len;
                byte[] tmp = new byte[2048];
                while ((len = instream.read(tmp)) != -1) {
                    System.out.println(new String(tmp, 0, len, ENC));
                }
            }








            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void makeAToast(String str) {
        //yet to implement
        Toast toast = Toast.makeText(this,str, Toast.LENGTH_LONG);
        toast.setGravity(Gravity.CENTER, 0, 0);
        toast.show();
    }



}

Answer 1

You can not instantiate Base64 class as it’s constructor is private. Check source of Base64(Line no. 740). You have static methods provided directly, you can call those directly as Base64.encode(string). Check doc