instanceof在Grails中 [英] instanceof in Grails

问题描述

如何确定类中的对象在集合中？

  class Human {...} 
 class Man extends Human {...} 
 class妇女扩展人类{...} 
 
 def humans = Human.findAll（）
 humans.each（）{human  - > 
 
 // ??? ，如果（人的instanceof女人）{printlnWoman} 
} 
  
 $ b 
非常感谢，
 
 Tom 
解决方案
根据你的描述，我会说你正在运行Hibernate代理对象（例如，类名是：Human _ $$  javaassist  *）。解决方法是使用GORM提供的insatnceOf版本。无需急于获取或使用其他方法。
  def planet = Planet.get（1）
 planet。 humans.each（）{human  - > 
 if（human.instanceOf（Man））{printlnis Man} 
 if（human.instanceOf（Woman））{printlnis Woman} 
} 
  
注意区别human.instanceOf（Man）而不是Man的人类instanceof。使用gorm方法而不是java关键字。  
 
 
您可以在[参考资料]中找到[解释] [1]的这部分内容。请参阅懒惰单端关联和代理小节
 
 
 
 [1]： http://grails.org/doc/latest/guide/single.html#5.5.2.8 渴望和懒惰获取
 
How to determine Class type of Object in collection?
class Human{...}
class Man extends Human{...}
class Women extends Human{...}

def humans = Human.findAll() 
humans.each(){ human ->

    // ??? , it is not work
   if ( human instanceof Man ) { println "Man" }
   if ( human instanceof Woman ) { println "Woman" }
}
Thanks a lot,

Tom
解决方案
Based on your description, I would say you are running into Hibernate proxy objects (ie. class name is: Human_$$javaassist*). Solution would be to use the GORM provided version of insatnceOf. No need to eager fetch or use a different method.
def planet = Planet.get(1)
planet.humans.each(){ human ->
    if (human.instanceOf(Man)) { println "is Man"}
    if (human.instanceOf(Woman)) { println "is Woman"}
}
Notice the difference human.instanceOf(Man) rather than human instanceof Man. Use the gorm method rather than the java keyword. 

You can see this section of the reference documentation for an [explanation][1]. See subsection "Lazy Single-Ended Associations and Proxies"

[1]: http://grails.org/doc/latest/guide/single.html#5.5.2.8 Eager and Lazy Fetching

                        
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