JAXB 需要一个公共的无参数构造函数来做什么?
在编组期间，JAXB 需要一个公共的无参数构造函数来做什么?
What does JAXB need a public no-arg constructor for, during marshalling?
Marshaller msh = ctx.createMarshaller();
msh.marshal(object, System.out);
我传递的是一个对象，而不是一个类.为什么 JAXB 需要构造函数?建造什么?
I'm passing an object, not a class. Why does JAXB need a constructor? To construct what?
推荐答案
在封送操作期间，JAXB 实现不应该需要无参数构造函数.JAXB 确实需要一个用于解组.通常，在创建 JAXBContext 时，缺少无参数构造函数会导致错误.您使用的 JAXB 实现可能会延迟初始化，直到执行实际操作.
A JAXB implementation should not need a no-arg constructor during a marshal operation. JAXB does require one for unmarshalling. Normally the absence of a no-arg constructor causes an error when the JAXBContext is created. The JAXB implementation you are using may be delaying initialization until an actual operation is performed.
一般来说，我们应该在 JAXB 的未来版本中考虑对多参数构造函数的支持.在 EclipseLink 的 JAXB (MOXy) 实现中，我们对此功能开放了一个增强请求(请随意添加相关的详情):
In general support for multi-arg constructors is something we should consider in a future version of JAXB. In the EclipseLink implementation of JAXB (MOXy) we have an enhancement request open for this functionality (feel free to add relevant details):
- https://bugs.eclipse.org/328951.
在当前版本的 JAXB 中，您可以使用 XmlAdapter 来支持此用例:
In the current version of JAXB you could use an XmlAdapter to support this use case:
- http://bdoughan.blogspot.com/2010/07/xmladapter-jaxbs-secret-weapon.html
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