Spring web services mainly use the contract-first approach when developing web services. In such a case you need to write the WSDL yourself.
With that said, you can generate a (first version ?) of your WSDL by writing an endpoint implementation class annotated with JAX-WS annotations and deploy it to a server (GlassFish or Tomcat with Metro, for example).
The JAX-WS web service stack will then generate the WSDL for you. This WSDL can then be used in subsequent development of the web service with Spring web services.