JAXB:如何避免xmlns:xsi的重复命名空间定义

marshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", new NamespacePrefixMapper() {
                @Override
                public String[] getPreDeclaredNamespaceUris() {
                    return new String[] { 
                        XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI
                    };
                }

                @Override
                public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
                    if (namespaceUri.equals(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI))
                        return "xsi";
                    if (namespaceUri.equals(XMLConstants.W3C_XML_SCHEMA_NS_URI))
                        return "xs";
                    if (namespaceUri.equals(WellKnownNamespace.XML_MIME_URI))
                        return "xmime";
                    return suggestion;

                }
            });

不 那个 但是您可以向根元素添加一个空schemaLocation:

marshaller.setProperty(Marshaller.JAXB_SCHEMA_LOCATION, "");

JAXB customization Namespace mapper issue

   <?xml version="1.0"?>
   <root>
      <ns1:element xmlns:ns1="urn:foo"> ... </ns1:element>
      <ns2:element xmlns:ns2="urn:foo"> ... </ns2:element>
      <ns3:element xmlns:ns3="urn:foo"> ... </ns3:element>
   </root>

JAXB也可以在XML文档的中间声明额外的命名空间,例如当有限定名称时( QName

问题是,自动生成的名称空间前缀(如ns1、ns2和ns3)对用户不友好——它们通常不能帮助人们理解编组的XML。

幸运的是,jaxb2.0(或更高版本)提供了一个名为 com.sun.xml.bind.marshaller.NamespacePrefixMapper

NamespacePrefixMapper 班级。结果,封送处理程序自动生成一个名称空间前缀,在本例中为ns2。

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <ns2:JustAnElement xmlns:ns2="a">
       <foo>true</foo>
   </ns2:JustAnElement>

避免命名空间重复的配置示例:

第二次编组由 JAXBSample 程序使用 分类如下:

   NamespacePrefixMapper m = new PreferredMapper();
               marshal(jc, e, m);

   public static class PreferredMapper extends NamespacePrefixMapper {
           @Override
           public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
               return "mappedNamespace" + namespaceUri;
           }
       }

getPreferredPrefix() 中的方法 PreferredMapper 类返回首选前缀,在本例中, mappedNamespacea 在封送XML的根元素处声明。

   <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
   <mappedNamespacea:JustAnElement xmlns:mappedNamespacea="a">
       <foo>true</foo>
   </mappedNamespacea:JustAnElement>

<dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.2.2</version>
            <type>jar</type>
            <scope>compile</scope>
        </dependency>

如果您按照上述示例中的定义配置注释,则不需要PreferredMapper。虽然我有一个package-info.jave文件,但有如下混淆:

@javax.xml.bind.annotation.XmlSchema(
        namespace = "mylovelynamespace1", 
        xmlns = {
                    @javax.xml.bind.annotation.XmlNs(prefix = "myns1", namespaceURI = "mylovelynamespace1"),
                    @javax.xml.bind.annotation.XmlNs(prefix = "myns2", namespaceURI = "mylovelynamespace2")
                }, 
                elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)
package com.mylovelycompanyname.package;

这是我在网上找到的最好的答案。

这个 xsi:type 声明很可能是因为 JAXBElement

如果 ObjectFactory 具有正确的 贾斯贝尔门特 您应该使用它,因为它应该正确地填充 QName 以及类型信息;否则,我将尝试设置 到 String.class (假设这是 commentTest CommentType.Comment .

资料来源: http://www.java.net/forum/topic/glassfish/metro-and-jaxb/how-do-i-remove-namespace-declarations-child-elements

所有者:

您只能编写一次名称空间。您将需要XMLStreamWriter的代理类和一个package-info.java。然后在代码中执行以下操作:

StringWriter stringWriter = new StringWriter();
XMLStreamWriter writer = new Wrapper((XMLStreamWriter) XMLOutputFactory
                                                               .newInstance().createXMLStreamWriter(stringWriter));
JAXBContext jaxbContext = JAXBContext.newInstance(Collection.class);
Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
jaxbMarshaller.marshal(books, writer);
System.out.println(stringWriter.toString());

代理类(重要方法是“writeNamespace”):

            class WrapperXMLStreamWriter implements XMLStreamWriter {

                   private final XMLStreamWriter writer;

                   public WrapperXMLStreamWriter(XMLStreamWriter writer) {
                       this.writer = writer;
                   }

                     //keeps track of what namespaces were used so that not to 
                     //write them more than once
                   private List<String> namespaces = new ArrayList<String>();

                   public void init(){
                       namespaces.clear();
                   }

                   public void writeStartElement(String localName) throws XMLStreamException {
                       init();
                       writer.writeStartElement(localName);

                   }

                   public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException {
                       init();
                       writer.writeStartElement(namespaceURI, localName);
                   }

                   public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
                       init();
                       writer.writeStartElement(prefix, localName, namespaceURI);
                   }

                   public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException {
                       if(namespaces.contains(namespaceURI)){ 
                           return;
                       }
                       namespaces.add(namespaceURI);
                       writer.writeNamespace(prefix, namespaceURI);
                   }

    // .. other delegation method, always the same pattern: writer.method() ...

}

package-info.java包:

@XmlSchema(elementFormDefault=XmlNsForm.QUALIFIED, attributeFormDefault=XmlNsForm.UNQUALIFIED ,
        xmlns = { 
        @XmlNs(namespaceURI = "http://www.w3.org/2001/XMLSchema-instance", prefix = "xsi")})
package your.package;

import javax.xml.bind.annotation.XmlNs;
import javax.xml.bind.annotation.XmlNsForm;
import javax.xml.bind.annotation.XmlSchema;

它是XML,因此可以使用DOM或XSLT处理输出,以消除多个名称空间引用。

nsPrefix 通过执行以下操作进行映射:

marshaller.setNamespaceMapping("myns","urn:foo");