JAXB命名空间及前缀_动力节点Java学院整理

JAXB命名空间及前缀_动力节点Java学院整理

本文讲解使用jaxb结合dom4j的XMLFilterImpl过滤器实现序列化和反序列化的完全控制

主要实现以下功能

序列化及反序列化时忽略命名空间

序列化时使用@XmlRootElement(namespace="http://lzrabbit.cn")注解作为类的默认命名空间，彻底消除命名空间前缀

序列化时引用类有不同命名空间时也不会生成命名空间前缀，而是在具体的xml节点上添加相应的xmlns声明

其它的xml节点命名及命名空间需求

同一个包下有多个命名空间

自定义命名空间前缀

依赖的jar dom4j

dom4j

dom4j

1.6.1

主要原理就是在序列化和反序列化时通过XMLFilterImpl的匿名实现类实现命名空间及xml节点名称的控制，实现多样化需求，废话不多说直接上代码，有更多个性化需求的看官请自行扩展

package com.bjpowernode.util;

import java.io.StringReader;

import java.io.StringWriter;

import javax.xml.bind.*;

import javax.xml.transform.sax.SAXSource;

import org.dom4j.io.OutputFormat;

import org.dom4j.io.XMLWriter;

import org.xml.sax.Attributes;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.XMLReader;

import org.xml.sax.helpers.XMLFilterImpl;

import org.xml.sax.helpers.XMLReaderFactory;

public class XmlUtil {

public static String toXML(Object obj) {

try {

JAXBContext context = JAXBContext.newInstance(obj.getClass());

Marshaller marshaller = context.createMarshaller();

marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");// //编码格式

marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);// 是否格式化生成的xml串

marshaller.setProperty(Marshaller.JAXB_FRAGMENT, false);// 是否省略xm头声明信息

StringWriter out = new StringWriter();

OutputFormat format = new OutputFormat();

format.setIndent(true);

format.setNewlines(true);

format.setNewLineAfterDeclaration(false);

XMLWriter writer = new XMLWriter(out, format);

XMLFilterImpl nsfFilter = new XMLFilterImpl() {

private boolean ignoreNamespace = false;

private String rootNamespace = null;

private boolean isRootElement = true;

@Override

public void startDocument() throws SAXException {

super.startDocument();

}

@Override

public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {

if (this.ignoreNamespace) uri = "";

if (this.isRootElement) this.isRootElement = false;

else if (!uri.equals("") && !localName.contains("xmlns")) localName = localName + " xmlns=\"" + uri + "\"";

super.startElement(uri, localName, localName, atts);

}

@Override

public void endElement(String uri, String localName, String qName) throws SAXException {

if (this.ignoreNamespace) uri = "";

super.endElement(uri, localName, localName);

}

@Override

public void startPrefixMapping(String prefix, String url) throws SAXException {

if (this.rootNamespace != null) url = this.rootNamespace;

if (!this.ignoreNamespace) super.startPrefixMapping("", url);

}

};

nsfFilter.setContentHandler(writer);

marshaller.marshal(obj, nsfFilter);

return out.toString();

} catch (Exception e) {

throw new RuntimeException(e);

}

}

public static T fromXML(String xml, Class valueType) {

try {

JAXBContext context = JAXBContext.newInstance(valueType);

Unmarshaller unmarshaller = context.createUnmarshaller();

// return (T) unmarshaller.unmarshal(new StringReader(xml));

SerializeUtil obj = new SerializeUtil();

XMLReader reader = XMLReaderFactory.createXMLReader();

XMLFilterImpl nsfFilter = new XMLFilterImpl() {

private boolean ignoreNamespace = false;

@Override

public void startDocument() throws SAXException {

super.startDocument();

}

@Override

public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {

if (this.ignoreNamespace) uri = "";

super.startElement(uri, localName, qName, atts);

}

@Override

public void endElement(String uri, String localName, String qName) throws SAXException {

if (this.ignoreNamespace) uri = "";

super.endElement(uri, localName, localName);

}

@Override

public void startPrefixMapping(String prefix, String url) throws SAXException {

if (!this.ignoreNamespace) super.startPrefixMapping("", url);

}

};

nsfFilter.setParent(reader);

InputSource input = new InputSource(new StringReader(xml));

SAXSource source = new SAXSource(nsfFilter, input);

return (T) unmarshaller.unmarshal(source);

} catch (Exception e) {

throw new RuntimeException(e.getMessage());

}

}

}

示例实体类

import javax.xml.bind.annotation.*;

@XmlRootElement(namespace="http://lzrabbit.cn/")

@XmlAccessorType(XmlAccessType.FIELD)

public class ClassA {

private int classAId;

@XmlElement(name="ClassAName")

private String classAName;

@XmlElement(namespace="http://cnblogs.com/")

private ClassB classB;

public int getClassAId() {

return classAId;

}

public void setClassAId(int classAId) {

this.classAId = classAId;

}

public String getClassAName() {

return classAName;

}

public void setClassAName(String classAName) {

this.classAName = classAName;

}

public ClassB getClassB() {

return classB;

}

public void setClassB(ClassB classB) {

this.classB = classB;

}

}

import javax.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)

public class ClassB {

private int ClassBId;

private String ClassBName;

public int getClassBId() {

return ClassBId;

}

public void setClassBId(int classBId) {

this.ClassBId = classBId;

}

public String getClassBName() {

return ClassBName;

}

public void setClassBName(String classBName) {

this.ClassBName = classBName;

}

}

调用

import com.bjpowernode.util.XmlUtil;

public class MainRun {

/**

* @param args

*/

public static void main(String[] args) {

ClassB classB = new ClassB();

classB.setClassBId(22);

classB.setClassBName("B2");

ClassA classA = new ClassA();

classA.setClassAId(11);

classA.setClassAName("A1");

classA.setClassBhttp://(classB);

System.out.println(XmlUtil.toXML(classA));

}

}

输出结果：

11

A1

22

B2

可以看到输出的xml完全达到我们的预期

实现细节都在代码里面了，很简单，当遇到有特殊需求的xml命名空间问题时，再也不用愁了

总结

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