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详解Java解析XML的四种方法

2013-01-22 09:06 537 查看
XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(DocumentObjectModel),DTD(DocumentTypeDefinition),SAX(SimpleAPIforXML),XSD(XmlSchemaDefinition),XSLT(ExtensibleStylesheetLanguageTransformations),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息。

XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX,另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。假设我们XML的内容和结构如下:

<?xmlversion="1.0"encoding="UTF-8"?>
<employees>
<employee>
<name>ddviplinux</name>
<sex>m</sex>
<age>30</age>
</employee>
</employees>

本文使用JAVA语言来实现DOM与SAX的XML文档生成与解析。
首先定义一个操作XML文档的接口XmlDocument它定义了XML文档的建立与解析的接口。

packagecom.alisoft.facepay.framework.bean;
/**
*
*@authorhongliang.dinghl
*定义XML文档建立与解析的接口
*/
publicinterfaceXmlDocument{
/**
*建立XML文档
*@paramfileName文件全路径名称
*/
publicvoidcreateXml(StringfileName);
/**
*解析XML文档
*@paramfileName文件全路径名称
*/
publicvoidparserXml(StringfileName);
}

1.DOM生成和解析XML文档

为XML文档的已解析版本定义了一组接口。解析器读入整个文档,然后构建一个驻留内存的树结构,然后代码就可以使用DOM接口来操作这个树结构。优点:整个文档树在内存中,便于操作;支持删除、修改、重新排列等多种功能;缺点:将整个文档调入内存(包括无用的节点),浪费时间和空间;使用场合:一旦解析了文档还需多次访问这些数据;硬件资源充足(内存、CPU)。

packagecom.alisoft.facepay.framework.bean; importjava.io.FileInputStream; importjava.io.FileNotFoundException; importjava.io.FileOutputStream; importjava.io.IOException; importjava.io.InputStream; importjava.io.PrintWriter; importjavax.xml.parsers.DocumentBuilder; importjavax.xml.parsers.DocumentBuilderFactory; importjavax.xml.parsers.ParserConfigurationException; importjavax.xml.transform.OutputKeys; importjavax.xml.transform.Transformer; importjavax.xml.transform.TransformerConfigurationException; importjavax.xml.transform.TransformerException; importjavax.xml.transform.TransformerFactory; importjavax.xml.transform.dom.DOMSource; importjavax.xml.transform.stream.StreamResult; importorg.w3c.dom.Document; importorg.w3c.dom.Element; importorg.w3c.dom.Node; importorg.w3c.dom.NodeList; importorg.xml.sax.SAXException; /** * *@authorhongliang.dinghl *DOM生成与解析XML文档 */ publicclassDomDemoimplementsXmlDocument{ privateDocumentdocument; privateStringfileName; publicvoidinit(){ try{ DocumentBuilderFactoryfactory=DocumentBuilderFactory .newInstance(); DocumentBuilderbuilder=factory.newDocumentBuilder(); this.document=builder.newDocument(); }catch(ParserConfigurationExceptione){ System.out.println(e.getMessage()); } } publicvoidcreateXml(StringfileName){ Elementroot=this.document.createElement("employees"); this.document.appendChild(root); Elementemployee=this.document.createElement("employee"); Elementname=this.document.createElement("name"); name.appendChild(this.document.createTextNode("丁宏亮")); employee.appendChild(name); Elementsex=this.document.createElement("sex"); sex.appendChild(this.document.createTextNode("m")); employee.appendChild(sex); Elementage=this.document.createElement("age"); age.appendChild(this.document.createTextNode("30")); employee.appendChild(age); root.appendChild(employee); TransformerFactorytf=TransformerFactory.newInstance(); try{ Transformertransformer=tf.newTransformer(); DOMSourcesource=newDOMSource(document); transformer.setOutputProperty(OutputKeys.ENCODING,"gb2312"); transformer.setOutputProperty(OutputKeys.INDENT,"yes"); PrintWriterpw=newPrintWriter(newFileOutputStream(fileName)); StreamResultresult=newStreamResult(pw); transformer.transform(source,result); System.out.println("生成XML文件成功!"); }catch(TransformerConfigurationExceptione){ System.out.println(e.getMessage()); }catch(IllegalArgumentExceptione){ System.out.println(e.getMessage()); }catch(FileNotFoundExceptione){ System.out.println(e.getMessage()); }catch(TransformerExceptione){ System.out.println(e.getMessage()); } } publicvoidparserXml(StringfileName){ try{ DocumentBuilderFactorydbf=DocumentBuilderFactory.newInstance(); DocumentBuilderdb=dbf.newDocumentBuilder(); Documentdocument=db.parse(fileName); NodeListemployees=document.getChildNodes(); for(inti=0;i<employees.getLength();i++){ Nodeemployee=employees.item(i); NodeListemployeeInfo=employee.getChildNodes(); for(intj=0;j<employeeInfo.getLength();j++){ Nodenode=employeeInfo.item(j); NodeListemployeeMeta=node.getChildNodes(); for(intk=0;k<employeeMeta.getLength();k++){ System.out.println(employeeMeta.item(k).getNodeName() +":"+employeeMeta.item(k).getTextContent()); } } } System.out.println("解析完毕"); }catch(FileNotFoundExceptione){ System.out.println(e.getMessage()); }catch(ParserConfigurationExceptione){ System.out.println(e.getMessage()); }catch(SAXExceptione){ System.out.println(e.getMessage()); }catch(IOExceptione){ System.out.println(e.getMessage()); } } }

  

2.SAX生成和解析XML文档

为解决DOM的问题,出现了SAX。SAX,事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时,发送事件,程序员编写响应这些事件的代码,保存数据。优点:不用事先调入整个文档,占用资源少;SAX解析器代码比DOM解析器代码小,适于Applet,下载。缺点:不是持久的;事件过后,若没保存数据,那么数据就丢了;无状态性;从事件中只能得到文本,但不知该文本属于哪个元素;使用场合:Applet;只需XML文档的少量内容,很少回头访问;机器内存少;

Java代码

packagecom.alisoft.facepay.framework.bean; importjava.io.FileInputStream; importjava.io.FileNotFoundException; importjava.io.IOException; importjava.io.InputStream; importjavax.xml.parsers.ParserConfigurationException; importjavax.xml.parsers.SAXParser; importjavax.xml.parsers.SAXParserFactory; importorg.xml.sax.Attributes; importorg.xml.sax.SAXException; importorg.xml.sax.helpers.DefaultHandler; /** * *@authorhongliang.dinghl *SAX文档解析 */ publicclassSaxDemoimplementsXmlDocument{ publicvoidcreateXml(StringfileName){ System.out.println("<<"+filename+">>"); } publicvoidparserXml(StringfileName){ SAXParserFactorysaxfac=SAXParserFactory.newInstance(); try{ SAXParsersaxparser=saxfac.newSAXParser(); InputStreamis=newFileInputStream(fileName); saxparser.parse(is,newMySAXHandler()); }catch(ParserConfigurationExceptione){ e.printStackTrace(); }catch(SAXExceptione){ e.printStackTrace(); }catch(FileNotFoundExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } } } classMySAXHandlerextendsDefaultHandler{ booleanhasAttribute=false; Attributesattributes=null; publicvoidstartDocument()throwsSAXException{ System.out.println("文档开始打印了"); } publicvoidendDocument()throwsSAXException{ System.out.println("文档打印结束了"); } publicvoidstartElement(Stringuri,StringlocalName,StringqName, Attributesattributes)throwsSAXException{ if(qName.equals("employees")){ return; } if(qName.equals("employee")){ System.out.println(qName); } if(attributes.getLength()>0){ this.attributes=attributes; this.hasAttribute=true; } } publicvoidendElement(Stringuri,StringlocalName,StringqName) throwsSAXException{ if(hasAttribute&&(attributes!=null)){ for(inti=0;i<attributes.getLength();i++){ System.out.println(attributes.getQName(0) +attributes.getValue(0)); } } } publicvoidcharacters(char[]ch,intstart,intlength) throwsSAXException{ System.out.println(newString(ch,start,length)); } } packagecom.alisoft.facepay.framework.bean; importjava.io.FileInputStream; importjava.io.FileNotFoundException; importjava.io.IOException; importjava.io.InputStream; importjavax.xml.parsers.ParserConfigurationException; importjavax.xml.parsers.SAXParser; importjavax.xml.parsers.SAXParserFactory; importorg.xml.sax.Attributes; importorg.xml.sax.SAXException; importorg.xml.sax.helpers.DefaultHandler; /** * *@authorhongliang.dinghl *SAX文档解析 */ publicclassSaxDemoimplementsXmlDocument{ publicvoidcreateXml(StringfileName){ System.out.println("<<"+filename+">>"); } publicvoidparserXml(StringfileName){ SAXParserFactorysaxfac=SAXParserFactory.newInstance(); try{ SAXParsersaxparser=saxfac.newSAXParser(); InputStreamis=newFileInputStream(fileName); saxparser.parse(is,newMySAXHandler()); }catch(ParserConfigurationExceptione){ e.printStackTrace(); }catch(SAXExceptione){ e.printStackTrace(); }catch(FileNotFoundExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } } } classMySAXHandlerextendsDefaultHandler{ booleanhasAttribute=false; Attributesattributes=null; publicvoidstartDocument()throwsSAXException{ System.out.println("文档开始打印了"); } publicvoidendDocument()throwsSAXException{ System.out.println("文档打印结束了"); } publicvoidstartElement(Stringuri,StringlocalName,StringqName, Attributesattributes)throwsSAXException{ if(qName.equals("employees")){ return; } if(qName.equals("employee")){ System.out.println(qName); } if(attributes.getLength()>0){ this.attributes=attributes; this.hasAttribute=true; } } publicvoidendElement(Stringuri,StringlocalName,StringqName) throwsSAXException{ if(hasAttribute&&(attributes!=null)){ for(inti=0;i<attributes.getLength();i++){ System.out.println(attributes.getQName(0) +attributes.getValue(0)); } } } publicvoidcharacters(char[]ch,intstart,intlength) throwsSAXException{ System.out.println(newString(ch,start,length)); } }

3.DOM4J生成和解析XML文档

DOM4J是一个非常非常优秀的JavaXMLAPI,具有性能优异、功能强大和极端易用使用的特点,同时它也是一个开放源代码的软件。如今你可以看到越来越多的Java软件都在使用DOM4J来读写XML,特别值得一提的是连Sun的JAXM也在用DOM4J。

Java代码

packagecom.alisoft.facepay.framework.bean; importjava.io.File; importjava.io.FileWriter; importjava.io.IOException; importjava.io.Writer; importjava.util.Iterator; importorg.dom4j.Document; importorg.dom4j.DocumentException; importorg.dom4j.DocumentHelper; importorg.dom4j.Element; importorg.dom4j.io.SAXReader; importorg.dom4j.io.XMLWriter; /** * *@authorhongliang.dinghl *Dom4j生成XML文档与解析XML文档 */ publicclassDom4jDemoimplementsXmlDocument{ publicvoidcreateXml(StringfileName){ Documentdocument=DocumentHelper.createDocument(); Elementemployees=document.addElement("employees"); Elementemployee=employees.addElement("employee"); Elementname=employee.addElement("name"); name.setText("ddvip"); Elementsex=employee.addElement("sex"); sex.setText("m"); Elementage=employee.addElement("age"); age.setText("29"); try{ WriterfileWriter=newFileWriter(fileName); XMLWriterxmlWriter=newXMLWriter(fileWriter); xmlWriter.write(document); xmlWriter.close(); }catch(IOExceptione){ System.out.println(e.getMessage()); } } publicvoidparserXml(StringfileName){ FileinputXml=newFile(fileName); SAXReadersaxReader=newSAXReader(); try{ Documentdocument=saxReader.read(inputXml); Elementemployees=document.getRootElement(); for(Iteratori=employees.elementIterator();i.hasNext();){ Elementemployee=(Element)i.next(); for(Iteratorj=employee.elementIterator();j.hasNext();){ Elementnode=(Element)j.next(); System.out.println(node.getName()+":"+node.getText()); } } }catch(DocumentExceptione){ System.out.println(e.getMessage()); } System.out.println("dom4jparserXml"); } }

4.JDOM生成和解析XML

为减少DOM、SAX的编码量,出现了JDOM;优点:20-80原则,极大减少了代码量。使用场合:要实现的功能简单,如解析、创建等,但在底层,JDOM还是使用SAX(最常用)、DOM、Xanan文档。

packagecom.alisoft.facepay.framework.bean; importjava.io.FileNotFoundException; importjava.io.FileOutputStream; importjava.io.IOException; importjava.util.List; importorg.jdom.Document; importorg.jdom.Element; importorg.jdom.JDOMException; importorg.jdom.input.SAXBuilder; importorg.jdom.output.XMLOutputter; /** * *@authorhongliang.dinghl *JDOM生成与解析XML文档 * */ publicclassJDomDemoimplementsXmlDocument{ publicvoidcreateXml(StringfileName){ Documentdocument; Elementroot; root=newElement("employees"); document=newDocument(root); Elementemployee=newElement("employee"); root.addContent(employee); Elementname=newElement("name"); name.setText("ddvip"); employee.addContent(name); Elementsex=newElement("sex"); sex.setText("m"); employee.addContent(sex); Elementage=newElement("age"); age.setText("23"); employee.addContent(age); XMLOutputterXMLOut=newXMLOutputter(); try{ XMLOut.output(document,newFileOutputStream(fileName)); }catch(FileNotFoundExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } } publicvoidparserXml(StringfileName){ SAXBuilderbuilder=newSAXBuilder(false); try{ Documentdocument=builder.build(fileName); Elementemployees=document.getRootElement(); ListemployeeList=employees.getChildren("employee"); for(inti=0;i<employeelist.size();i++){<br="">Elementemployee=(Element)employeeList.get(i); ListemployeeInfo=employee.getChildren(); for(intj=0;j<employeeinfo.size();j++){<br="">System.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue()); } } }catch(JDOMExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } } }

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