如何从Grails控制器和视图外部引用Grails域类字段？

class Person {
    String name
}

def personInstance = Person.get(id)
def name = personInstance.name

<p>${personInstance.name}</p>

class CommonService {
    String getPersonName(Person person) {
        return person.name
    }
}

def commonService

def someAction() {
    def personInstance = Person.get(id)
    def name = commonService.getPersonName(personInstance)
}

<p>${commonService.getPersonName(personInstance)}</p>