multipart request support

src/main/java/org/scribe/model/Request.java

@@ -26,6 +26,7 @@ class Request
   private String payload = null;
   private HttpURLConnection connection;
   private String charset;
+  private byte[] bytePayload = null;
 
   /**
    * Creates a new Http Request
@@ -77,7 +78,7 @@ class Request
     addHeaders(connection);
     if (verb.equals(Verb.PUT) || verb.equals(Verb.POST))
     {
-      addBody(connection, getBodyContents());
+      addBody(connection, getByteBodyContents());
     }
     return new Response(connection);
   }
@@ -88,13 +89,11 @@ class Request
       conn.setRequestProperty(key, headers.get(key));
   }
 
-  void addBody(HttpURLConnection conn, String content) throws IOException
+  void addBody(HttpURLConnection conn, byte[] content) throws IOException
   {
-    if (this.charset == null)
-      this.charset = Charset.defaultCharset().name();
-    conn.setRequestProperty(CONTENT_LENGTH, String.valueOf(content.getBytes(charset).length));
+    conn.setRequestProperty(CONTENT_LENGTH, String.valueOf(content.length));
     conn.setDoOutput(true);
-    conn.getOutputStream().write(content.getBytes(charset));
+    conn.getOutputStream().write(content);
   }
 
   /**
@@ -145,6 +144,16 @@ class Request
     this.payload = payload;
   }
 
+  /**
+   * Overloaded version for byte arrays
+   *
+   * @param payload
+   */
+  public void addPayload(byte[] payload)
+  {
+    this.bytePayload = payload;
+  }
+
   /**
    * Get a {@link Map} of the query string parameters.
    * 
@@ -201,10 +210,32 @@ class Request
    * Returns the body of the request
    * 
    * @return form encoded string
+   * @throws OAuthException if the charset chosen is not supported
    */
   public String getBodyContents()
   {
-    return (payload != null) ? payload : URLUtils.formURLEncodeMap(bodyParams);
+    try
+    {
+      return new String(getByteBodyContents(),getCharset());
+    }
+    catch(UnsupportedEncodingException uee)
+    {
+      throw new OAuthException("Unsupported Charset: "+charset, uee);
+    }
+  }
+
+  byte[] getByteBodyContents()
+  {
+    if (bytePayload != null) return bytePayload;
+    String body = (payload != null) ? payload : URLUtils.formURLEncodeMap(bodyParams);
+    try
+    {
+      return body.getBytes(getCharset());
+    }
+    catch(UnsupportedEncodingException uee)
+    {
+      throw new OAuthException("Unsupported Charset: "+getCharset(), uee);
+    }
   }
 
   /**
@@ -227,6 +258,16 @@ class Request
     return headers;
   }
 
+  /**
+   * Returns the connection charset. Defaults to {@link Charset} defaultCharset if not set
+   *
+   * @return charset
+   */
+  public String getCharset()
+  {
+    return charset == null ? Charset.defaultCharset().name() : charset;
+  }
+
   /**
    * Sets the connect timeout for the underlying {@link HttpURLConnection}
    *