XSD有2个根元素(一次1个)

Question

所以这是一个复杂/迟钝的情况.我正在编写XSD,并且恰好需要2个根元素(在任何给定时间为1)

<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>

在任何给定的时间,这些元素中的任何一个都将用作根元素,因此XML看起来像

<bookList>
<book>
<author>XYZ</author>
</book>
</bookList>

要么

<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发送？author = XYZ,单个book将从localhost/book_name.xml发送

我怎样才能用一个xml实现这个目标？我尝试将书定义放在XSD中,但JAXB2.1没有生成任何Book类.有什么东西我错过了吗？

---

EDIT1:已生成BookType但BookType没有任何根元素.

Answer 1

XML SCHEMA

我正在编写XSD,并且恰好需要2个根元素(在任何给定时间为1)

下面的XML架构支持具有两个根元素booksList和book你所期待的.

<?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)实现将为指定的复杂类型生成一个类bookType,然后bookElement它将@XmlElementDecl在ObjectFactory类上创建一个注释.

BooksList

@XmlRootElement在此类上生成了一个类,因为它对应于具有匿名复杂类型的全局元素.

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;
    }

}

的BookType

生成此类以对应于指定的复杂类型.

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;
    }

}

的ObjectFactory

与命名复杂类型对应的全局元素@XmlElementDecl在ObjectFactory类上生成注释.这是必要的,因为多个全局元素可以对应于命名的复杂类型.

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.

booksList.xml

<booksList>
    <book>
        <author>XYZ</author>
    </book>
</booksList>

是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,则会返回一个实例,JAXBElement该实例包含对应于指定复杂类型的域对象.

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();
    }

}

UPDATE

下面是一个代码片段,演示了如何将一个实例包装成BookType一个JAXBElement可以编组的代码片段.

ObjectFactory objectFactory = new ObjectFactory();
JAXBElement<BookType> jaxbElement = objectFactory.createBook(aBookType);
marshaller.marshal(jaxbElement, System.out);