added optional commons-codec dependency

there are some platforms (e.g. android) that do not have by default the java.xml.bind package. The solution is to use the commons-codec implementation if it's on the classpath and fallback to java.xml.bind

Author: fernandezpablo85

pom.xml

@@ -38,14 +38,19 @@
   </scm>
 
   <dependencies>
-
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.8.1</version>
       <scope>test</scope>
     </dependency>
-
+    <dependency>
+      <groupId>commons-codec</groupId>
+      <artifactId>commons-codec</artifactId>
+      <version>1.4</version>
+      <scope>compile</scope>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
   <build>
     <plugins>

src/main/java/org/scribe/oauth/OAuth10aServiceImpl.java

@@ -4,6 +4,7 @@
 
 import org.scribe.builder.api.*;
 import org.scribe.model.*;
+import org.scribe.services.*;
 import org.scribe.utils.*;
 import java.util.concurrent.TimeUnit;
 
@@ -139,6 +140,7 @@ public String getAuthorizationUrl(Token requestToken)
   private String getSignature(OAuthRequest request, Token token)
   {
     config.log("generating signature...");
+    config.log("using base64 encoder: " + Base64Encoder.type());
     String baseString = api.getBaseStringExtractor().extract(request);
     String signature = api.getSignatureService().getSignature(baseString, config.getApiSecret(), token.getSecret());
 

src/main/java/org/scribe/services/Base64Encoder.java

@@ -0,0 +1,36 @@
+package org.scribe.services;
+
+public abstract class Base64Encoder
+{
+  private static Base64Encoder instance;
+
+  public static synchronized Base64Encoder getInstance()
+  {
+    if (instance == null)
+    {
+      instance = createEncoderInstance();
+    }
+    return instance;
+  }
+
+  private static Base64Encoder createEncoderInstance()
+  {
+    if (CommonsEncoder.isPresent())
+    {
+      return new CommonsEncoder();
+    }
+    else
+    {
+      return new DatatypeConverterEncoder();
+    }
+  }
+
+  public static String type()
+  {
+    return getInstance().getType();
+  }
+
+  public abstract String encode(byte[] bytes);
+
+  public abstract String getType();
+}

src/main/java/org/scribe/services/CommonsEncoder.java

@@ -0,0 +1,42 @@
+package org.scribe.services;
+
+import org.apache.commons.codec.binary.*;
+import org.scribe.exceptions.*;
+
+import java.io.UnsupportedEncodingException;
+
+public class CommonsEncoder extends Base64Encoder
+{
+
+  @Override
+  public String encode(byte[] bytes)
+  {
+    try
+    {
+      return new String(Base64.encodeBase64(bytes), "UTF-8");
+    }
+    catch (UnsupportedEncodingException e)
+    {
+      throw new OAuthSignatureException("Can't perform base64 encoding", e);
+    }
+  }
+
+  @Override
+  public String getType()
+  {
+    return "CommonsCodec";
+  }
+
+  public static boolean isPresent()
+  {
+    try
+    {
+      Class.forName("org.apache.commons.codec.binary.Base64");
+      return true;
+    }
+    catch (ClassNotFoundException e)
+    {
+      return false;
+    }
+  }
+}

src/main/java/org/scribe/services/DatatypeConverterEncoder.java

@@ -0,0 +1,18 @@
+package org.scribe.services;
+
+import javax.xml.bind.*;
+
+public class DatatypeConverterEncoder extends Base64Encoder
+{
+  @Override
+  public String encode(byte[] bytes)
+  {
+    return DatatypeConverter.printBase64Binary(bytes);
+  }
+
+  @Override
+  public String getType()
+  {
+    return "DatatypeConverter";
+  }
+}

src/main/java/org/scribe/services/HMACSha1SignatureService.java

@@ -6,9 +6,6 @@
 import org.scribe.exceptions.*;
 import org.scribe.utils.*;
 
-// implementation of base64 encoding lives here.
-import javax.xml.bind.DatatypeConverter;
-
 /**
  * HMAC-SHA1 implementation of {@SignatureService}
  * 
@@ -51,7 +48,7 @@ private String doSign(String toSign, String keyString) throws Exception
 
   private String bytesToBase64String(byte[] bytes)
   {
-    return DatatypeConverter.printBase64Binary(bytes);
+    return Base64Encoder.getInstance().encode(bytes);
   }
 
   /**

src/main/java/org/scribe/services/RSASha1SignatureService.java

@@ -3,9 +3,6 @@
 import org.scribe.exceptions.*;
 import java.security.*;
 
-// implementation of base64 encoding lives here.
-import javax.xml.bind.DatatypeConverter;
-
 /**
  * A signature service that uses the RSA-SHA1 algorithm.
  */
@@ -42,7 +39,7 @@ public String getSignature(String baseString, String apiSecret, String tokenSecr
 
   private String bytesToBase64String(Signature signature) throws SignatureException
   {
-    return DatatypeConverter.printBase64Binary(signature.sign());
+    return Base64Encoder.getInstance().encode(signature.sign());
   }
 
   /**