JAXB命名空间及前缀_动力节点Java学院整理

2023-09-26 01:30:07 320

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://www.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jardom4j


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

packagecom.bjpowernode.util;

importjava.io.StringReader;
importjava.io.StringWriter;

importjavax.xml.bind.*;
importjavax.xml.transform.sax.SAXSource;

importorg.dom4j.io.OutputFormat;
importorg.dom4j.io.XMLWriter;
importorg.xml.sax.Attributes;
importorg.xml.sax.InputSource;
importorg.xml.sax.SAXException;
importorg.xml.sax.XMLReader;
importorg.xml.sax.helpers.XMLFilterImpl;
importorg.xml.sax.helpers.XMLReaderFactory;

publicclassXmlUtil{

publicstaticStringtoXML(Objectobj){
try{
JAXBContextcontext=JAXBContext.newInstance(obj.getClass());

Marshallermarshaller=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

StringWriterout=newStringWriter();
OutputFormatformat=newOutputFormat();
format.setIndent(true);
format.setNewlines(true);
format.setNewLineAfterDeclaration(false);
XMLWriterwriter=newXMLWriter(out,format);

XMLFilterImplnsfFilter=newXMLFilterImpl(){
privatebooleanignoreNamespace=false;
privateStringrootNamespace=null;
privatebooleanisRootElement=true;

@Override
publicvoidstartDocument()throwsSAXException{
super.startDocument();
}

@Override
publicvoidstartElement(Stringuri,StringlocalName,StringqName,Attributesatts)throwsSAXException{
if(this.ignoreNamespace)uri="";
if(this.isRootElement)this.isRootElement=false;
elseif(!uri.equals("")&&!localName.contains("xmlns"))localName=localName+"xmlns=\""+uri+"\"";

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

@Override
publicvoidendElement(Stringuri,StringlocalName,StringqName)throwsSAXException{
if(this.ignoreNamespace)uri="";
super.endElement(uri,localName,localName);
}

@Override
publicvoidstartPrefixMapping(Stringprefix,Stringurl)throwsSAXException{
if(this.rootNamespace!=null)url=this.rootNamespace;
if(!this.ignoreNamespace)super.startPrefixMapping("",url);

}
};
nsfFilter.setContentHandler(writer);
marshaller.marshal(obj,nsfFilter);
returnout.toString();

}catch(Exceptione){
thrownewRuntimeException(e);
}
}

publicstaticTfromXML(Stringxml,ClassvalueType){
try{
JAXBContextcontext=JAXBContext.newInstance(valueType);
Unmarshallerunmarshaller=context.createUnmarshaller();
//return(T)unmarshaller.unmarshal(newStringReader(xml));
SerializeUtilobj=newSerializeUtil();
XMLReaderreader=XMLReaderFactory.createXMLReader();
XMLFilterImplnsfFilter=newXMLFilterImpl(){
privatebooleanignoreNamespace=false;

@Override
publicvoidstartDocument()throwsSAXException{
super.startDocument();
}

@Override
publicvoidstartElement(Stringuri,StringlocalName,StringqName,Attributesatts)throwsSAXException{
if(this.ignoreNamespace)uri="";
super.startElement(uri,localName,qName,atts);
}

@Override
publicvoidendElement(Stringuri,StringlocalName,StringqName)throwsSAXException{
if(this.ignoreNamespace)uri="";
super.endElement(uri,localName,localName);
}

@Override
publicvoidstartPrefixMapping(Stringprefix,Stringurl)throwsSAXException{
if(!this.ignoreNamespace)super.startPrefixMapping("",url);
}
};
nsfFilter.setParent(reader);
InputSourceinput=newInputSource(newStringReader(xml));
SAXSourcesource=newSAXSource(nsfFilter,input);
return(T)unmarshaller.unmarshal(source);
}catch(Exceptione){
thrownewRuntimeException(e.getMessage());
}
}
}

示例实体类

importjavax.xml.bind.annotation.*;

@XmlRootElement(namespace="http://www.lzrabbit.cn/")
@XmlAccessorType(XmlAccessType.FIELD)
publicclassClassA{
privateintclassAId;

@XmlElement(name="ClassAName")
privateStringclassAName;

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

publicintgetClassAId(){
returnclassAId;
}
publicvoidsetClassAId(intclassAId){
this.classAId=classAId;
}

publicStringgetClassAName(){
returnclassAName;
}

publicvoidsetClassAName(StringclassAName){
this.classAName=classAName;
}

publicClassBgetClassB(){
returnclassB;
}

publicvoidsetClassB(ClassBclassB){
this.classB=classB;
}
}

importjavax.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)
publicclassClassB{
privateintClassBId;
privateStringClassBName;

publicintgetClassBId(){
returnClassBId;
}

publicvoidsetClassBId(intclassBId){
this.ClassBId=classBId;
}

publicStringgetClassBName(){
returnClassBName;
}

publicvoidsetClassBName(StringclassBName){
this.ClassBName=classBName;
}
}

调用

importcom.bjpowernode.util.XmlUtil;

publicclassMainRun{

/**
*@paramargs
*/
publicstaticvoidmain(String[]args){

ClassBclassB=newClassB();
classB.setClassBId(22);
classB.setClassBName("B2");

ClassAclassA=newClassA();
classA.setClassAId(11);
classA.setClassAName("A1");
classA.setClassB(classB);

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

}

输出结果：

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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JAXB命名空间及前缀_动力节点Java学院整理

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