java restful web services @path regular expression

1
         The following example shows how regular expression could be used with the @Path annotation.
       @Path("users/{username: regular expression}")

         Example:
        @Path("users/{username: [a-zA-Z][a-zA-Z_0-9]}")

        following URL:   http://example.com/users/hello

2
                 The @PathParam annotation example

        @Path("/users/{username}")
        public class User {

        @GET
         @Produces("text/xml")
         public String getUser(@PathParam("username") String              userName) {
        System.out.println(userName);
        }
        }



                   following URL:   http://example.com/users/hello

3
                      Ignore any character in the @Path.

                                      @GET
               @Path("/report/download/file/{filename : .+}")
               @Produces(MediaType.APPLICATION_OCTET_STREAM)
                public Response                                downloadFilebyPath(@PathParam("filename")  String fileName) {
               System.out.println("file location:--- //"+fileName);
               }
                                   following URL: http://example.com/users/xxxx/xxxxxx/xxxxx/xxxxx.xxx

                                  {filename : .+} this will accept any  character.
                                 When you are sending any file complete path or directory name in the URL that                                       contain '/ or \ or  any symbol' this logic is Useful.