I have had good luck configuring Cross-origin resource sharing (CORS) for my API (on Wildfly) by using this lib:
<dependency>
<groupId>com.thetransactioncompany</groupId>
<artifactId>cors-filter</artifactId>
<version>2.1</version>
</dependency>
It's very easy to setup. Just add the above dependency to your pom and then add the following config to the webapp section of your web.xml file.
<filter>
<filter-name>CORS</filter-name>
<filter-class>com.thetransactioncompany.cors.CORSFilter</filter-class>
<init-param>
<param-name>cors.allowGenericHttpRequests</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>cors.allowOrigin</param-name>
<param-value>*</param-value>
</init-param>
<init-param>
<param-name>cors.allowSubdomains</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>cors.supportedMethods</param-name>
<param-value>GET, HEAD, POST, DELETE, OPTIONS</param-value>
</init-param>
<init-param>
<param-name>cors.supportedHeaders</param-name>
<param-value>*</param-value>
</init-param>
<init-param>
<param-name>cors.supportsCredentials</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>cors.maxAge</param-name>
<param-value>3600</param-value>
</init-param>
</filter>
<filter-mapping>
<!-- CORS Filter mapping -->
<filter-name>CORS</filter-name>
<url-pattern>*</url-pattern>
</filter-mapping>
You can also configure it with a properties file instead if you prefer. This lib works like a charm and gives you a lot of configuration flexibility!