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Webservice-XML与Java（五）

孤风一剑 10月 15, 2013 257 0

处理XML的有很多工具，比如SAX、DOM4J等，还有一种解析XML方式是stax，此为oracle公司提出基于流（stream）来处理的方式，在Java中封装成了stax，和sax很像，在webservice中一般使用基于流的工具，基于dom的或多或少的会影响一些效率。WS中还要涉及到Java对象和XML之间的转换，可以直接使用JDK提供的JAXB。类似的还有：XStream、Jackson、json-lib，这些框架提供了xml和json，json和java对象的转换，根据具体的需求可选择不同的框架。

Jaxb的用法很简单，把Java对象转换为xml叫编排，xml转换为Java对象叫反编排，实例如下：

 

[java][/java] view plaincopy

  1. package com.tgb.xml;
  3. import java.io.StringReader;
  5. import javax.xml.bind.JAXBContext;
  6. import javax.xml.bind.JAXBException;
  7. import javax.xml.bind.Marshaller;
  8. import javax.xml.bind.Unmarshaller;
  10. import org.junit.Test;
  13. public class TestJaxb {
  15.     @Test
  16.     public void test01(){
  17.         try {
  18.             JAXBContext ctx = JAXBContext.newInstance(Student.class);
  19.             Marshaller marshaller = ctx.createMarshaller();
  20.             Student stu = new Student(1,”这是”,”32″,new Classroom(1,”计算机”,”2012″));
  21.             marshaller.marshal(stu, System.out);
  22.         } catch (JAXBException e) {
  23.             e.printStackTrace();
  24.         }
  25.     }
  27.     @Test
  28.     public void test02(){
  29.         try {
  30.             String xml = “<?xml version=\”1.0\” encoding=\”UTF-8\” standalone=\”yes\”?><student><age>32</age><classroom><grade>2012</grade><id>1</id><name>计算机</name></classroom><id>1</id><name>这是</name></student>”;
  31.             JAXBContext ctx = JAXBContext.newInstance(Student.class);
  32.             Unmarshaller um = ctx.createUnmarshaller();
  33.             Student stu = (Student)um.unmarshal(new StringReader(xml));
  34.             System.out.println(stu.getName() + “,” + stu.getClassroom().getName());
  35.         } catch (JAXBException e) {
  36.             e.printStackTrace();
  37.         }
  38.     }
  39. }

 

下面主要讲stax操作xml的实例，首先创建一个xml文档：

 

[html][/html] view plaincopy

  1. <?xml version=”1.0″ encoding=”ISO-8859-1″?>
  3. <bookstore>
  5.     <book category=”COOKING”>
  6.         <title lang=”en”>
  7.             Everyday Italian
  8.         </title>
  9.         <author>Giada De Laurentiis</author>
  10.         <year>2005</year>
  11.         <price>30.00</price>
  12.     </book>
  14.     <book category=”CHILDREN”>
  15.         <title lang=”en”>Harry Potter</title>
  16.         <author>J K. Rowling</author>
  17.         <year>2005</year>
  18.         <price>29.99</price>
  19.     </book>
  21.     <book category=”WEB”>
  22.         <title lang=”en”>XQuery Kick Start</title>
  23.         <author>James McGovern</author>
  24.         <author>Per Bothner</author>
  25.         <author>Kurt Cagle</author>
  26.         <author>James Linn</author>
  27.         <author>Vaidyanathan Nagarajan</author>
  28.         <year>2003</year>
  29.         <price>49.99</price>
  30.     </book>
  32.     <book category=”WEB”>
  33.         <title lang=”en”>Learning XML</title>
  34.         <author>Erik T. Ray</author>
  35.         <year>2003</year>
  36.         <price>39.95</price>
  37.     </book>
  39. </bookstore>

 

基于光标的查找：

 

[java][/java] view plaincopy

  1. @Test
  2. public void test01(){
  3.     XMLInputFactory factory = XMLInputFactory.newInstance();
  5.     InputStream is = null;
  7.     is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  9.     XMLStreamReader reader;
  10.     try {
  11.         reader = factory.createXMLStreamReader(is);
  13.         while(reader.hasNext()){
  14.             int type = reader.next();
  16.             if(type == XMLStreamConstants.START_ELEMENT){ //起始节点
  17.                 System.out.println(reader.getName());
  18.             }else if(type == XMLStreamConstants.CHARACTERS){ //文本节点
  19.                 System.out.println(reader.getText());
  20.             }else if(type == XMLStreamConstants.END_ELEMENT){ //结束节点
  21.                 System.out.println(“/” + reader.getName());
  22.             }
  23.         }
  25.     } catch (XMLStreamException e) {
  26.         e.printStackTrace();
  27.     }finally{
  28.         if(is != null){
  29.             try {
  30.                 is.close();
  31.             } catch (IOException e) {
  32.                 e.printStackTrace();
  33.             }
  34.         }
  35.     }
  36. }
  38. @Test
  39. public void test02(){
  41.     XMLInputFactory factory = XMLInputFactory.newInstance();
  43.     InputStream is = null;
  45.     is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  47.     XMLStreamReader reader;
  48.     try {
  49.         reader = factory.createXMLStreamReader(is);
  51.         while(reader.hasNext()){
  52.             int type = reader.next();
  54.             if(type == XMLStreamConstants.START_ELEMENT){
  55.                 String name = reader.getName().toString();
  56.                 if(“book”.equals(name)){
  57.                     //读取属性名和值
  58.                     System.out.println(reader.getAttributeName(0) + “:” + reader.getAttributeValue(0));
  59.                 }
  61.                 //获取元素内容
  62.                 if(“price”.equals(name)){
  63.                     System.out.println(reader.getElementText() + “\n”);
  64.                 }
  65.             }
  66.         }
  68.     } catch (XMLStreamException e) {
  69.         e.printStackTrace();
  70.     }finally{
  71.         if(is != null){
  72.             try {
  73.                 is.close();
  74.             } catch (IOException e) {
  75.                 e.printStackTrace();
  76.             }
  77.         }
  78.     }
  79. }

 

基于迭代模型查找：

 

[java][/java] view plaincopy

  1. @Test
  2.     public void test03(){
  4.         XMLInputFactory factory = XMLInputFactory.newInstance();
  6.         InputStream is = null;
  8.         is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  10.         try {
  11.             //基于迭代模型的操作方式
  12.             XMLEventReader reader = factory.createXMLEventReader(is);
  13.             int num = 0;
  14.             while(reader.hasNext()){
  15.                 //通过XMLEvent来获取是否是某种节点类型
  16.                 XMLEvent event = reader.nextEvent();
  17.                 if(event.isStartElement()){
  18.                     //通过event.asxxx转换节点
  19.                     String name = event.asStartElement().getName().toString();
  20.                     if(“title”.equals(name)){
  21.                         System.out.println(reader.getElementText() + “:”);
  22.                     }
  23.                     if(“price”.equals(name)){
  24.                         System.out.println(reader.getElementText() + “\n”);
  25.                     }
  26.                 }
  27.                 num++;
  28.             }
  29.             System.out.println(num);
  30.         } catch (XMLStreamException e) {
  31.             e.printStackTrace();
  32.         }finally{
  33.             if(is != null){
  34.                 try {
  35.                     is.close();
  36.                 } catch (IOException e) {
  37.                     e.printStackTrace();
  38.                 }
  39.             }
  40.         }
  41.     }

 

过滤器的使用：

 

[java][/java] view plaincopy

  1. @Test
  2.     public void test04(){
  4.         XMLInputFactory factory = XMLInputFactory.newInstance();
  6.         InputStream is = null;
  8.         is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  10.         try {
  12.             //基于Filter的过滤方式，可以有效的过滤不用进行操作的节点，效率高
  13.             XMLEventReader reader = factory.createFilteredReader(factory.createXMLEventReader(is), new EventFilter() {
  15.                 @Override
  16.                 public boolean accept(XMLEvent event) {
  17.                     if(event.isStartElement()){
  18.                         String name = event.asStartElement().getName().toString();
  19.                         if(name.equals(“title”) || name.equals(“price”)){
  20.                             return true;
  21.                         }
  22.                     }
  23.                     return false;
  24.                 }
  25.             });
  27.             int num = 0;
  28.             while(reader.hasNext()){
  29.                 XMLEvent event = reader.nextEvent();
  30.                 if(event.isStartElement()){
  31.                     String name = event.asStartElement().getName().toString();
  32.                     if(“title”.equals(name)){
  33.                         System.out.println(reader.getElementText() + “:”);
  34.                     }
  35.                     if(“price”.equals(name)){
  36.                         System.out.println(reader.getElementText() + “\n”);
  37.                     }
  38.                 }
  39.                 num++;
  40.             }
  41.             System.out.println(num);
  42.         } catch (XMLStreamException e) {
  43.             e.printStackTrace();
  44.         }finally{
  45.             if(is != null){
  46.                 try {
  47.                     is.close();
  48.                 } catch (IOException e) {
  49.                     e.printStackTrace();
  50.                 }
  51.             }
  52.         }
  53.     }

 

XPath的使用：

 

[java][/java] view plaincopy

  1. @Test
  2.     public void test05(){
  4.         XMLInputFactory factory = XMLInputFactory.newInstance();
  6.         InputStream is = null;
  8.         try{
  9.             is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  11.             //创建文档处理对象
  12.             DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
  14.             //通过DocumentBuilder创建doc的文档对象
  15.             Document doc = db.parse(is);
  17.             //创建xpath
  18.             XPath xpath = XPathFactory.newInstance().newXPath();
  20.             //第一个参数就是xpath，第二个参数就是文档
  21.             NodeList list = (NodeList)xpath.evaluate(“//book[@category=’WEB’]”, doc, XPathConstants.NODESET);
  23.             for(int i=0;i<list.getLength();i++){
  24.                 //遍历输出相应的结果
  25.                 Element e = (Element)list.item(i);
  26.                 System.out.println(e.getElementsByTagName(“title”).item(0).getTextContent());
  27.             }
  28.         } catch (Exception e) {
  29.             e.printStackTrace();
  30.         }finally{
  31.             if(is != null){
  32.                 try {
  33.                     is.close();
  34.                 } catch (IOException e) {
  35.                     e.printStackTrace();
  36.                 }
  37.             }
  38.         }
  39.     }

 

使用XMLStreamWriter创建xml：

 

[java][/java] view plaincopy

  1. @Test
  2.     public void test06(){
  4.         try {
  5.             XMLStreamWriter xsw = XMLOutputFactory.newInstance().createXMLStreamWriter(System.out);
  6.             xsw.writeStartDocument(“utf-8”, “1.0”);
  7.             xsw.writeEndDocument();
  8.             String ns = “http://www.tgb.com”;
  9.             xsw.writeStartElement(“prefix”,”person”,ns);
  10.             xsw.writeStartElement(ns,”id”);
  11.             xsw.writeCharacters(“1”);
  12.             xsw.writeEndElement();
  13.             xsw.writeEndElement();
  14.             xsw.flush();
  15.             xsw.close();
  16.         } catch (XMLStreamException e) {
  17.             e.printStackTrace();
  18.         } catch (FactoryConfigurationError e) {
  19.             e.printStackTrace();
  20.         }
  21.     }

 

使用Transformer更新节点信息：

 

[java][/java] view plaincopy

  1. @Test
  2.     public void test07(){
  4.         try {
  5.             InputStream is = TestStax.class.getClassLoader().getResourceAsStream(“books.xml”);
  7.             //创建文档处理对象
  8.             DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
  10.             //通过DocumentBuilder创建doc文档对象
  11.             Document doc = db.parse(is);
  13.             //创建xpath
  14.             XPath xpath = XPathFactory.newInstance().newXPath();
  16.             Transformer tran = TransformerFactory.newInstance().newTransformer();
  18.             tran.setOutputProperty(OutputKeys.ENCODING, “UTF-8”);
  19.             tran.setOutputProperty(OutputKeys.INDENT, “yes”);
  21.             //第一个参数就是xpath，第二个参数就是文档
  22.             NodeList list = (NodeList)xpath.evaluate(“//book[title=’Learning XML’]”,doc,XPathConstants.NODESET);
  24.             //获取price节点
  25.             Element be = (Element)list.item(0);
  26.             Element e = (Element)(be.getElementsByTagName(“price”).item(0));
  28.             e.setTextContent(“232323”);
  29.             Result result = new StreamResult(System.out);
  30.             //修改源
  31.             tran.transform(new DOMSource(doc), result);
  33.         } catch (Exception e) {
  34.             e.printStackTrace();
  35.         }
  36.     }

 

以上都是stax的简单应用，具体可参考JDK。

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