您可以将JAXB与StAX解析器一起使用，并执行以下操作：
顾客
域模型中的每个属性都将映射为
@XmlElement(nillable=true,type=Object.class)。设置
type=Object.class将强制将
xsi:type属性写出。
package forum8198945;import java.util.Date; import javax.xml.bind.annotation.*;@XmlRootElementpublic 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
我们将为创建一个包装器，以
XMLStreamWriter剥离所有我们不想写入XML的信息。
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
我们需要为此创建一个包装器，
XMLStreamReader以添加我们在上剥离的所有内容
XMLStreamWriter。
XMLStreamReader因为我们可以扩展，所以这样做更容易
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); }}演示版
以下内容演示了所有内容如何结合在一起：
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(); }}输出量
<?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.Stringnull 1 class java.lang.IntegerFri Nov 25 13:36:49 EST 2011 class java.util.Date
