获取“Class”来自泛型类型T的对象 [英] Get "Class" object from generic type T

问题描述

我想制作返回XML文档的Object表示的泛型函数（使用JAXB）。我需要将class对象传递给JAXBContext构造函数，但是我怎样才能从T中获得它？

  public< T> readXmlToObject（String xmlFileName，T jaxbClass）{
 JAXBContext context = JAXBContext.newInstance（T.class）; // T.class  - 这里错误，如何得到它？ 
 ....... 
} 
  

解决方案 $ p
$ b

  public< T> 
传递类对象，而且很容易。 T readXmlToObject（String xmlFileName，Class< T> jaxbClass）{
 JAXBContext context = JAXBContext.newInstance（jaxbClass）; // T.class  - 这里错误，如何得到它？ 
 Object o = context.createUnmarshaller（）。unmarshal（new File（xmlFileName））; 
返回jaxbClass.cast（o）; 
 
 
 
 
 
 $ b 
这里的想法是因为你不能从对象，你必须以相反的方式来做：从类开始，然后操纵对象以匹配类型参数。
 
I want to make generic function that return Object representation of XML document (using JAXB). I need to pass "class" object to JAXBContext constructor, but how I can get it from T? 
public <T> readXmlToObject(String xmlFileName, T  jaxbClass) {
   JAXBContext context = JAXBContext.newInstance(T.class); // T.class - here error, how to get it?
   .......
}

解决方案
Pass the class object instead and it's easy.
public <T> T readXmlToObject(String xmlFileName, Class<T>  jaxbClass) {
       JAXBContext context = JAXBContext.newInstance( jaxbClass ); // T.class - here error, how to get it?
       Object o = context.createUnmarshaller().unmarshal( new File( xmlFileName ) );
       return jaxbClass.cast( o );
}
The idea here is that since you can't extract the type parameter from the object, you have to do it the other way around: start with the class and then manipulate the object to match the type parameter.

                        
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