问题描述
所以这是一个复杂/迟缓的情况.我正在编写一个 XSD，碰巧有一个要求，我需要 2 个根元素(在任何给定时间都需要 1 个)
So here is a complex/retarded situation. I am writing an XSD and there happens to be a requirement where i need 2 root elements (1 at any given time)
<xs:element name="booksList">
<xs:complexType>
<xs:sequence>
<xs:element name="book" type="bookType" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
然后
<xs:element name="book" type="bookType"></xs:element>
在任何给定时间，这些元素中的任何一个都将用作根元素，因此 XML 看起来像
at any given time, either of these element will be used as the root element, so an XML would look like
<bookList>
<book>
<author>XYZ</author>
</book>
</bookList>
或
<book>
<author>XYZ</author>
</book>
这两个 XML 都将从 2 个不同的 URL 发送回用户，即列表将从 localhost/books.xml?author=XYZ 发送，单本书将从 发送>localhost/book_name.xml
Both of these XML will be sent back to the user from 2 different URL's i.e. the list will be sent from localhost/books.xml?author=XYZ and single book will be sent from localhost/book_name.xml
我怎样才能用一个 xml 实现这一目标?我尝试将书籍定义放在 XSD 中，但 JAXB2.1 没有生成任何 Book 类.有什么我遗漏的吗?
How can i achieve this with one xml ? I tried putting the book definition in the XSD but JAXB2.1 didn't generate any Book class. Is there something which i am missing ?
EDIT1:已生成 BookType，但 BookType 没有任何根元素.
EDIT1: BookType has been generated but BookType doesn't have any root element.
推荐答案
XML SCHEMA
我正在编写一个 XSD 并且恰好在我需要的地方有一个要求2 个根元素(在任何给定时间 1 个)
下面的 XML 模式支持您正在寻找的两个根元素 booksList 和 book.
The XML schema below supports having the two root elements booksList and book that you are looking for.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="booksList">
<xs:complexType>
<xs:sequence>
<xs:element name="book" type="bookType" minOccurs="0"
maxOccurs="unbounded" />
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="book" type="bookType"></xs:element>
<xs:complexType name="bookType">
<xs:sequence>
<xs:element name="author" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:schema>
生成模型
我尝试将书籍定义放在 XSD 中，但 JAXB2.1 没有生成任何 Book 类.
您的 JAXB (JSR-222) 实现将为命名的复杂类型 bookType 生成一个类，然后为 bookElement 创建一个 @XmlElementDecl<ObjectFactory 类上的/code> 注释.
Your JAXB (JSR-222) implementation will generate a class for the named complex type bookType, then for the bookElement it will create an @XmlElementDecl annotation on the ObjectFactory class.
图书列表
在这个类上生成了一个带有 @XmlRootElement 的类，因为它对应于一个具有匿名复杂类型的全局元素.
A class with an @XmlRootElement was generated on this class because it corresponds to a global element with an anonymous complex type.
package forum11620825;
import java.util.*;
import javax.xml.bind.annotation.*;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {"book"})
@XmlRootElement(name = "booksList")
public class BooksList {
protected List<BookType> book;
public List<BookType> getBook() {
if (book == null) {
book = new ArrayList<BookType>();
}
return this.book;
}
}
BookType
生成这个类是为了对应命名的复杂类型.
This class was generated to correspond to the named complex types.
package forum11620825;
import javax.xml.bind.annotation.*;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "bookType", propOrder = {"author"})
public class BookType {
@XmlElement(required = true)
protected String author;
public String getAuthor() {
return author;
}
public void setAuthor(String value) {
this.author = value;
}
}
对象工厂
与命名复杂类型对应的全局元素具有在 ObjectFactory 类上生成的 @XmlElementDecl 注释.这是必要的，因为多个全局元素可能对应于命名的复杂类型.
Global elements that correspond to named complex types have @XmlElementDecl annotations generated on the ObjectFactory class. This is necessary since multiple global elements could correspond to named complex types.
package forum11620825;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.XmlElementDecl;
import javax.xml.bind.annotation.XmlRegistry;
import javax.xml.namespace.QName;
@XmlRegistry
public class ObjectFactory {
private final static QName _Book_QNAME = new QName("", "book");
public ObjectFactory() {
}
public BooksList createBooksList() {
return new BooksList();
}
public BookType createBookType() {
return new BookType();
}
@XmlElementDecl(namespace = "", name = "book")
public JAXBElement<BookType> createBook(BookType value) {
return new JAXBElement<BookType>(_Book_QNAME, BookType.class, null, value);
}
}
XML
以下是您问题中的 XML 文档.
Below are the XML documents from your question.
booksList.xml
<booksList>
<book>
<author>XYZ</author>
</book>
</booksList>
book.xml
<book>
<author>XYZ</author>
</book>
演示代码
当您解组根元素对应于 @XmlRootElement 注释的文档时，您将获得相应域对象的实例.如果您解组根元素对应于 @XmlElementDecl 注释的文档，您将返回一个 JAXBElement 实例，该实例包装了与命名复杂类型对应的域对象.
When you unmarshal a document in which the root element corresponds to an @XmlRootElement annotation you get an instance of the corresponding domain object. If you unmarshal a document in which the root element corresponds to an @XmlElementDecl annotation you get back an instance of JAXBElement that wraps a domain object corresponding to the named complex type.
package forum11620825;
import java.io.File;
import javax.xml.bind.*;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance("forum11620825");
Unmarshaller unmarshaller = jc.createUnmarshaller();
File input1 = new File("src/forum11620825/booksList.xml");
BooksList bookList = (BooksList) unmarshaller.unmarshal(input1);
File input2 = new File("src/forum11620825/book.xml");
JAXBElement<BookType> je = (JAXBElement<BookType>) unmarshaller.unmarshal(input2);
BookType bookType = je.getValue();
}
}
更新
下面的代码片段演示了如何将 BookType 的实例包装在 JAXBElement 中，以便对其进行编组.
Below is a code fragment demonstrating how to wrap an instance of BookType in a JAXBElement so that it can be marshalled.
ObjectFactory objectFactory = new ObjectFactory();
JAXBElement<BookType> jaxbElement = objectFactory.createBook(aBookType);
marshaller.marshal(jaxbElement, System.out);
这篇关于XSD 具有 2 个根元素(一次 1 个)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！