grails处理json数据

import grails.converters.JSON

class User{
   String nickname
   Integer age
}
class TestController{
   def listAsJson = {
      def output = "{'nickname':'东瓜','age':'16'}"
      render output as JSON
   }
   def listAsJSON2 = {
      def output = "{'nickname':'东瓜','age':'16'}"
      render JSON.parse(output)
   }
   def listAsJSON3 = {
      def user = User.get(1)
      render user as JSON
   }
   def listAsJSON4 = {
      def outputMap = ['1':1,'2':2]
      render outputMap as JSON
   }
}