@FormParam
When the input request body is of the type "application/x-www-form-urlencoded", a.k.a. an HTML Form, you can inject individual form parameters from the request body into method parameter values.
<form method="POST" action="/resources/service">
First name:
<input type="text" name="firstname">
<br>
Last name:
<input type="text" name="lastname">
</form>
If you post through that form, this is what the service might look like:
@Path("/")
public class NameRegistry {
@Path("/resources/service")
@POST
public void addName(@FormParam("firstname") String first, @FormParam("lastname") String last) {...}
You cannot combine @FormParam with the default "application/x-www-form-urlencoded" that unmarshalls to a MultivaluedMap<String, String>. i.e. This is illegal:
@Path("/")
public class NameRegistry {
@Path("/resources/service")
@POST
@Consumes("application/x-www-form-urlencoded")
public void addName(@FormParam("firstname") String first, MultivaluedMap<String, String> form) {...}