Added Kaixin2, Renren and SinaWeibo2 Apis and examples.

src/main/java/org/scribe/builder/api/SinaWeiboApi20.java

@@ -0,0 +1,46 @@
+package org.scribe.builder.api;
+
+import org.scribe.extractors.*;
+import org.scribe.model.*;
+import org.scribe.utils.*;
+
+/**
+ * SinaWeibo OAuth 2.0 api.
+ */
+public class SinaWeiboApi20 extends DefaultApi20
+{
+  private static final String AUTHORIZE_URL = "https://api.weibo.com/oauth2/authorize?client_id=%s&redirect_uri=%s&response_type=code";
+  private static final String SCOPED_AUTHORIZE_URL = AUTHORIZE_URL + "&scope=%s";
+
+  @Override
+  public Verb getAccessTokenVerb()
+  {
+    return Verb.POST;
+  }
+
+  @Override
+  public AccessTokenExtractor getAccessTokenExtractor()
+  {
+    return new JsonTokenExtractor();
+  }
+
+  @Override
+  public String getAccessTokenEndpoint()
+  {
+    return "https://api.weibo.com/oauth2/access_token?grant_type=authorization_code";
+  }
+
+  @Override
+  public String getAuthorizationUrl(OAuthConfig config)
+  {
+    // Append scope if present
+    if (config.hasScope())
+    {
+      return String.format(SCOPED_AUTHORIZE_URL, config.getApiKey(), OAuthEncoder.encode(config.getCallback()), OAuthEncoder.encode(config.getScope()));
+    }
+    else
+    {
+      return String.format(AUTHORIZE_URL, config.getApiKey(), OAuthEncoder.encode(config.getCallback()));
+    }
+  }
+}