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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jar dom4j
<dependency>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
<version>1.6.1</version>
</dependency>
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 cn.lzrabbit.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> T fromXML(String xml, Class<T> 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://www.lzrabbit.cn/")
@XmlAccessorType(XmlAccessType.FIELD)
public class ClassA {
private int classAId;@XmlElement(name="ClassAName")
private String classAName;@XmlElement(namespace="http://www.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 cn.lzrabbit.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.setClassB(classB);System.out.println(XmlUtil.toXML(classA));
}}
输出结果：
<?xml version="1.0" encoding="UTF-8"?>
<classA xmlns="http://www.lzrabbit.cn/">
<classAId>11</classAId>
<ClassAName>A1</ClassAName>
<classB xmlns="http://www.cnblogs.com/">
<ClassBId>22</ClassBId>
<ClassBName>B2</ClassBName>
</classB>
</classA>
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