无法理解JAXB Unmarshalling行为 [英] Unable to understand JAXB Unmarshalling behaviour

问题描述

参考我的上一篇文章 。我有以下代码从文件中读取XML。

Reference to my previous post. I have following code which is reading XML from the file.

logger.log(Level.INFO, "testSchemaChange");
JAXBContext jaxbContext = JAXBContext.newInstance("com.store.web.ws.v1.model");
Unmarshaller unmarshaller = jaxbContext.createUnmarshaller();
JAXBElement<BookType> jeBookType = (JAXBElement<BookType>) unmarshaller.unmarshal(new File (BOOK_XML));

BookType bookType = jeBookType.getValue();
logger.log(Level.INFO, "Book recieved: " + bookType.getISBN());

我正在使用预订播种XML我的根元素而不是 BookList 。只要我在 JAXBContext.newInstance 中保留包的完整路径，此示例就可以正常工作。

I am seeding an XML with Book as my root element instead of BookList. This example is working fine as long as i keep the full path of the package in the JAXBContext.newInstance.

我刚刚更改

JAXBContext jaxbContext = JAXBContext.newInstance（ com.store.web.ws.v1.model）;

到

JAXBContext jaxbContext = JAXBContext.newInstance（BookType.class）;

我开始获得异常 SEVERE：意外元素（uri：，local：book）。预期的元素是（无）

有人可以解释为什么会出现这种情况？

Can someone explain why is this behaviour ?

PS：
为方便起见，我的测试类和JAXB生成的类在同一个包中，即 com.store.web.ws .v1.model

推荐答案

您看到的问题是因为 JAXBContext 不知道您的 ObjectFactory 类，其中包含 @XmlElementDecl 注释 book 元素。

The problem you are seeing is because the JAXBContext isn't aware of your ObjectFactory class that contains the @XmlElementDecl annotation for the book element.

当您创建 JAXBContext 时一个包名，它会自动拉入 ObjectFactory 类。如果在类上创建 JAXContext ，则需要使用 @XmlRegistry 注释显式包含该类（ ObjectFactory 在这种情况下）。

When you create a JAXBContext on a package name, the it will automatically pull in the ObjectFactory class. If you create a JAXContext on classes you need to explicitly include the class with the @XmlRegistry annotation (ObjectFactory in this case).

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