JAXB命名空間及前綴_動力節(jié)點Java學院整理

更新時間：2017年08月22日 11:07:37 作者：lzrabbit

這篇文章主要給大家介紹了關(guān)于JAXB命名空間及前綴的相關(guān)資料，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨著小編來一起學習學習吧。

本文講解使用jaxb結(jié)合dom4j的XMLFilterImpl過濾器實現(xiàn)序列化和反序列化的完全控制

主要實現(xiàn)以下功能

序列化及反序列化時忽略命名空間
序列化時使用@XmlRootElement(namespace="http://www.lzrabbit.cn")注解作為類的默認命名空間，徹底消除命名空間前綴
序列化時引用類有不同命名空間時也不會生成命名空間前綴，而是在具體的xml節(jié)點上添加相應的xmlns聲明
其它的xml節(jié)點命名及命名空間需求
同一個包下有多個命名空間
自定義命名空間前綴

依賴的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時通過XMLFilterImpl的匿名實現(xiàn)類實現(xiàn)命名空間及xml節(jié)點名稱的控制，實現(xiàn)多樣化需求，廢話不多說直接上代碼，有更多個性化需求的看官請自行擴展

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");// //編碼格式
   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頭聲明信息

   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());
  }
 }
}

示例實體類

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;
 }
}

調(diào)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.setClassB(classB);

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

}

輸出結(jié)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>

可以看到輸出的xml完全達到我們的預期

實現(xiàn)細節(jié)都在代碼里面了，很簡單，當遇到有特殊需求的xml命名空間問題時，再也不用愁了

總結(jié)

以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學習或者工作能帶來一定的幫助，如果有疑問大家可以留言交流，謝謝大家對腳本之家的支持。

您可能感興趣的文章: