如何在 JAXB 中设置非命名空间的 nil 和数据类型属性
我在 Scala 中使用 JAXB,我的编组代码如下所示:
I'm using JAXB with Scala, my marshalling code looks like this:
def marshalToXml(): String = {
val context = JAXBContext.newInstance(this.getClass())
val writer = new StringWriter
context.createMarshaller.marshal(this, writer)
writer.toString()
}
然后对于我的可空元素,我使用注释 @XmlElement(nillable = true)
根据 带有空字段的 JAXB 编组.这给了我这样的 XML 输出:
Then for my nullable elements I'm using the annotation @XmlElement(nillable = true)
as per JAXB Marshalling with null fields. This gives me XML output like so:
<name>Alex Dean</name>
<customerReference xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>
<quantity>1</quantity>
<createdAt>2011-05-14T00:00:00+03:00</createdAt>
这是一个好的开始,但我真正想为这些字段编组的是:
This is a good start but what I'd really like to marshal for these fields is:
<name>Alex Dean</name>
<customerReference nil="true"/>
<quantity type="integer">1</quantity>
<createdAt type="datetime">2011-05-14T00:00:00+03:00</createdAt>
换句话说,我想删除命名空间属性和前缀,并为除字符串之外的所有内容添加显式 XML 数据类型属性.这可能很简单,但我似乎无法在 JAXB 文档中找到方法.
In other words, I would like to remove the namespace attributes and prefixes, and add in explicit XML datatype attributes for all but strings. It's probably quite simple to do but I can't seem to find how in the JAXB documentation.
感谢您的帮助!
推荐答案
您可以将 JAXB 与 StAX 解析器一起使用并执行以下操作:
You could use JAXB with a StAX parser and do the following:
客户
域模型中的每个属性都将使用 @XmlElement(nillable=true, type=Object.class)
进行映射.设置 type=Object.class
将强制写出 xsi:type
属性.
Each property in your domain model will be mapped with @XmlElement(nillable=true, type=Object.class)
. Setting the type=Object.class
will force an xsi:type
attribute to be written out.
package forum8198945;
import java.util.Date;
import javax.xml.bind.annotation.*;
@XmlRootElement
public class Customer {
private String name;
private Customer customerReference;
private Integer quantity;
private Date createdAt;
@XmlElement(nillable=true, type=Object.class)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@XmlElement(nillable=true, type=Object.class)
public Customer getCustomerReference() {
return customerReference;
}
public void setCustomerReference(Customer customerReference) {
this.customerReference = customerReference;
}
@XmlElement(nillable=true, type=Object.class)
public Integer getQuantity() {
return quantity;
}
public void setQuantity(Integer quantity) {
this.quantity = quantity;
}
@XmlElement(nillable=true, type=Object.class)
public Date getCreatedAt() {
return createdAt;
}
public void setCreatedAt(Date createdAt) {
this.createdAt = createdAt;
}
}
XMLStreamWriterWrapper
我们将为 XMLStreamWriter
编写一个创建包装器,以剥离所有我们不想写入 XML 的信息.
We will write a create a wrapper for an XMLStreamWriter
that strips off all the information we do not want written to XML.
package forum8198945;
import javax.xml.namespace.NamespaceContext;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
public class XMLStreamWriterWrapper implements XMLStreamWriter {
private XMLStreamWriter xmlStreamWriter;
public XMLStreamWriterWrapper(XMLStreamWriter xmlStreamWriter) {
this.xmlStreamWriter = xmlStreamWriter;
}
public void writeStartElement(String localName) throws XMLStreamException {
xmlStreamWriter.writeStartElement(localName);
}
public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException {
xmlStreamWriter.writeStartElement(namespaceURI, localName);
}
public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
xmlStreamWriter.writeStartElement(prefix, localName, namespaceURI);
}
public void writeEmptyElement(String namespaceURI, String localName) throws XMLStreamException {
xmlStreamWriter.writeEmptyElement(namespaceURI, localName);
}
public void writeEmptyElement(String prefix, String localName, String namespaceURI) throws XMLStreamException {
xmlStreamWriter.writeEmptyElement(prefix, localName, namespaceURI);
}
public void writeEmptyElement(String localName) throws XMLStreamException {
xmlStreamWriter.writeEmptyElement(localName);
}
public void writeEndElement() throws XMLStreamException {
xmlStreamWriter.writeEndElement();
}
public void writeEndDocument() throws XMLStreamException {
xmlStreamWriter.writeEndDocument();
}
public void close() throws XMLStreamException {
xmlStreamWriter.close();
}
public void flush() throws XMLStreamException {
xmlStreamWriter.flush();
}
public void writeAttribute(String localName, String value) throws XMLStreamException {
xmlStreamWriter.writeAttribute(localName, value);
}
public void writeAttribute(String prefix, String namespaceURI, String localName, String value) throws XMLStreamException {
if("http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) {
int colonIndex = value.indexOf(':');
if(colonIndex > -1) {
value = value.substring(colonIndex + 1);
}
xmlStreamWriter.writeAttribute(localName, value);
} else {
xmlStreamWriter.writeAttribute(prefix, namespaceURI, localName, value);
}
}
public void writeAttribute(String namespaceURI, String localName, String value) throws XMLStreamException {
if("http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) {
int colonIndex = value.indexOf(':');
if(colonIndex > -1) {
value = value.substring(colonIndex + 1);
}
xmlStreamWriter.writeAttribute(localName, value);
} else {
xmlStreamWriter.writeAttribute(namespaceURI, localName, value);
}
}
public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException {
if(!"http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI) && !"http://www.w3.org/2001/XMLSchema".equals(namespaceURI)) {
xmlStreamWriter.writeNamespace(prefix, namespaceURI);
}
}
public void writeDefaultNamespace(String namespaceURI) throws XMLStreamException {
if(!"http://www.w3.org/2001/XMLSchema-instance".equals(namespaceURI)) {
xmlStreamWriter.writeDefaultNamespace(namespaceURI);
}
}
public void writeComment(String data) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeProcessingInstruction(String target) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeProcessingInstruction(String target, String data) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeCData(String data) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeDTD(String dtd) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeEntityRef(String name) throws XMLStreamException {
// TODO Auto-generated method stub
}
public void writeStartDocument() throws XMLStreamException {
xmlStreamWriter.writeStartDocument();
}
public void writeStartDocument(String version) throws XMLStreamException {
xmlStreamWriter.writeStartDocument(version);
}
public void writeStartDocument(String encoding, String version) throws XMLStreamException {
xmlStreamWriter.writeStartDocument(encoding, version);
}
public void writeCharacters(String text) throws XMLStreamException {
xmlStreamWriter.writeCharacters(text);
}
public void writeCharacters(char[] text, int start, int len) throws XMLStreamException {
xmlStreamWriter.writeCharacters(text, start, len);
}
public String getPrefix(String uri) throws XMLStreamException {
return xmlStreamWriter.getPrefix(uri);
}
public void setPrefix(String prefix, String uri) throws XMLStreamException {
xmlStreamWriter.setPrefix(prefix, uri);
}
public void setDefaultNamespace(String uri) throws XMLStreamException {
xmlStreamWriter.setDefaultNamespace(uri);
}
public void setNamespaceContext(NamespaceContext context) throws XMLStreamException {
xmlStreamWriter.setNamespaceContext(context);
}
public NamespaceContext getNamespaceContext() {
return xmlStreamWriter.getNamespaceContext();
}
public Object getProperty(String name) throws IllegalArgumentException {
return xmlStreamWriter.getProperty(name);
}
}
XMLStreamReaderWrapper
我们需要为 XMLStreamReader
创建一个包装器,它添加我们在 XMLStreamWriter
上剥离的所有内容.这对于 XMLStreamReader
来说更容易做到,因为我们可以扩展 StreamReaderDelegate
.
We need to create a wrapper for XMLStreamReader
that adds everything that we stripped off on the XMLStreamWriter
. This is easier to do for XMLStreamReader
since we can extend StreamReaderDelegate
.
package forum8198945;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;
public class XMLStreamReaderWrapper extends StreamReaderDelegate {
public XMLStreamReaderWrapper(XMLStreamReader xmlStreamReader) {
super(xmlStreamReader);
}
@Override
public String getAttributeNamespace(int index) {
String attributeName = getAttributeLocalName(index);
if("type".equals(attributeName) || "nil".equals(attributeName)) {
return "http://www.w3.org/2001/XMLSchema-instance";
}
return super.getAttributeNamespace(index);
}
}
演示
以下内容展示了所有内容是如何结合在一起的:
The following demonstrates how everything comes together:
package forum8198945;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Date;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamWriter;
public class Demo {
public static void main(String[] args) throws Exception {
JAXBContext jc = JAXBContext.newInstance(Customer.class);
Customer customer = new Customer();
customer.setName("Alex Dean");
customer.setCustomerReference(null);
customer.setQuantity(1);
customer.setCreatedAt(new Date());
StringWriter stringWriter = new StringWriter();
XMLOutputFactory xof = XMLOutputFactory.newFactory();
XMLStreamWriter xsw = xof.createXMLStreamWriter(stringWriter);
xsw = new XMLStreamWriterWrapper(xsw);
Marshaller marshaller = jc.createMarshaller();
marshaller.marshal(customer, xsw);
String xml = stringWriter.toString();
System.out.println(xml);
XMLInputFactory xif = XMLInputFactory.newFactory();
xif.createXMLStreamReader(new StringReader(xml));
printValue(customer.getName());
printValue(customer.getCustomerReference());
printValue(customer.getQuantity());
printValue(customer.getCreatedAt());
}
private static void printValue(Object value) {
System.out.print(value);
System.out.print(" ");
if(null != value) {
System.out.print(value.getClass());
}
System.out.println();
}
}
输出
<?xml version="1.0"?><customer><createdAt type="dateTime">2011-11-25T13:36:49.095</createdAt><customerReference nil="true"></customerReference><name type="string">Alex Dean</name><quantity type="int">1</quantity></customer>
Alex Dean class java.lang.String
null
1 class java.lang.Integer
Fri Nov 25 13:36:49 EST 2011 class java.util.Date
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