Java XML格式化，文件到XML，XML到文档

扩展标记语言(XML)是不同应用程序之间的消息传递和通信的流行媒介之一。 由于XML是开源的，并且通过DTD和XSD提供对数据格式的控制，因此它广泛用于各种技术。

Java XML格式化程序

第三方API将Document对象和XML消息作为String返回，这里编写了一个简单的XmlFormatter类来使用适当的缩进格式化XML并将Document对象转换为XML String。

 package com.test.java.xmlutil;  import org.apache.xml.serialize.OutputFormat; import org.apache.xml.serialize.XMLSerializer; import org.w3c.dom.Document; import org.xml.sax.InputSource; import org.xml.sax.SAXException;  import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult;  import java.io.IOException; import java.io.StringReader; import java.io.StringWriter; import java.io.Writer;  /**  * Utility Class for formatting XML  * @author Pankaj  *  */ public class XmlFormatter {      /**      *      * @param unformattedXml - XML String      * @return Properly formatted XML String      */     public String format(String unformattedXml) {         try {             Document document = parseXmlFile(unformattedXml);              OutputFormat format = new OutputFormat(document);             format.setLineWidth(65);             format.setIndenting(true);             format.setIndent(2);             Writer out = new StringWriter();             XMLSerializer serializer = new XMLSerializer(out, format);             serializer.serialize(document);              return out.toString();         } catch (IOException e) {             e.printStackTrace();             return "";         }      }      /**      * This function converts String XML to Document object      * @param in - XML String      * @return Document object      */     private Document parseXmlFile(String in) {         try {             DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();             DocumentBuilder db = dbf.newDocumentBuilder();             InputSource is = new InputSource(new StringReader(in));             return db.parse(is);         } catch (ParserConfigurationException e) {             throw new RuntimeException(e);         } catch (SAXException e) {             throw new RuntimeException(e);         } catch (IOException e) {             e.printStackTrace();         }         return null;     }     /**      * Takes an XML Document object and makes an XML String. Just a utility      * function.      *      * @param doc - The DOM document      * @return the XML String      */     public String makeXMLString(Document doc) {         String xmlString = "";         if (doc != null) {             try {                 TransformerFactory transfac = TransformerFactory.newInstance();                 Transformer trans = transfac.newTransformer();                 trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");                 trans.setOutputProperty(OutputKeys.INDENT, "yes");                 StringWriter sw = new StringWriter();                 StreamResult result = new StreamResult(sw);                 DOMSource source = new DOMSource(doc);                 trans.transform(source, result);                 xmlString = sw.toString();             } catch (Exception e) {                 e.printStackTrace();             }         }         return xmlString;     }     public static void main(String args[]){         XmlFormatter formatter = new XmlFormatter();         String book = "<?xml version=/"1.0/"?><catalog><book id=/"bk101/"><author>Gambardella, Matthew</author><title>XML Developers Guide</title><genre>Computer</genre><price>44.95</price><publish_date>2000-10-01</publish_date><description>An in-depth look at creating applications with XML.</description></book><book id=/"bk102/"><author>Ralls, Kim</author><title>Midnight Rain</title><genre>Fantasy</genre><price>5.95</price><publish_date>2000-12-16</publish_date><description>A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.</description></book></catalog>";         System.out.println(formatter.format(book));     } } 

要使用此类，需要Apache xercesImpl.jar，可以从他们的网站下载。上述类的输出是格式正确的XML字符串：

 <?xml version="1.0" encoding="UTF-8"?> <catalog>   <book id="bk101">     <author>Gambardella, Matthew</author>     <title>XML Developers Guide</title>     <genre>Computer</genre>     <price>44.95</price>     <publish_date>2000-10-01</publish_date>     <description>An in-depth look at creating applications with XML.</description>   </book>   <book id="bk102">     <author>Ralls, Kim</author>     <title>Midnight Rain</title>     <genre>Fantasy</genre>     <price>5.95</price>     <publish_date>2000-12-16</publish_date>     <description>A former architect battles corporate zombies, an evil       sorceress, and her own childhood to become queen of the world.</description>   </book> </catalog> 

这个实用程序类用于在java中格式化xml并将XML转换为Document，反之亦然。