本文講解使用jaxb結合dom4j的XMLFilterImpl過濾器實現序列化和反序列化的完全控制
主要實現以下功能
- 序列化及反序列化時忽略命名空間
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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節點上添加相應的xmlns聲明
- 其它的xml節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
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<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的匿名實現類實現命名空間及xml節點名稱的控制，實現多樣化需求，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
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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
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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; }} |
調用
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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)); }} |
輸出結果：
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<?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
實現細節都在代碼里面了，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
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