【Java】XML文件的解析

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;

 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NodeList;
 import org.xml.sax.SAXException;

 public abstract class XMLReader {
     // 只需要一份 documentBuilder
     private static DocumentBuilder documentBuilder;

     static {
         try {
             documentBuilder = DocumentBuilderFactory
                     .newInstance()
                     .newDocumentBuilder();
         } catch (ParserConfigurationException e) {
             e.printStackTrace();
         }
     }

     public XMLReader() {
     }

     // 获取Document，Document是w3c的，不要导错了
     public static Document openDocument(InputStream is) {
         Document document = null;
         try {
             document = documentBuilder.parse(is);
         } catch (SAXException | IOException e) {
             e.printStackTrace();
         } finally {
             try {
                 is.close();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }

         return document;
     }

     public static Document openDocument(String xmlPath) {
         InputStream is = XMLReader.class.getResourceAsStream(xmlPath);
         if (is == null) {
             try {
                 // 自定义异常
                 throw new XMLFileNotExistException("文件[" + xmlPath+ "]不存在!");
             } catch (XMLFileNotExistException e) {
                 e.printStackTrace();
             }
         } 

         return openDocument(is);
     }

     public static Document openDocument(File path) {
         InputStream is = null;
         try {
             is = new FileInputStream(path);
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         }
         return openDocument(is);
     }

     // 抽象方法，由用户自行处理得到的标签
     public abstract void dealElment(Element element, int index);

     // 抽象方法在for循环中，每次读取到一个标签，就交给抽象方法，由用户自行使用
     public XMLReader parse(Element element, String tagname) {
         NodeList nodeList = element.getElementsByTagName(tagname);

         for (int index = 0; index < nodeList.getLength(); index++) {
             Element ele = (Element) nodeList.item(index);

             dealElment(ele, index);
         }

         return this;
     }

     public XMLReader parse(Document document, String tagname) {
         NodeList nodeList = document.getElementsByTagName(tagname);

         for (int index = 0; index < nodeList.getLength(); index++) {
             Element element = (Element) nodeList.item(index);

             dealElment(element, index);
         }

         return this;
     }

 }

这是我们的XML文件，对其进行解析

 <?xml version="1.0" encoding="UTF-8"?>
 <Test>
     <class name = "第一个标签" type = "firstLable">
         <parameter id = "one" value = "一"></parameter>
         <parameter id = "two" value = "二"></parameter>
         <parameter id = "thr" value = "三"></parameter>
     </class>
     <class name = "第二个标签" type = "secondLable">
         <parameter id = "four" value = "四"></parameter>
         <parameter id = "six" value = "五"></parameter>
     </class>
 </Test>

public static void main(String[] args) {
    new XMLReader() {

        @Override
        public void dealElment(Element element, int index) {
            String name = element.getAttribute("name");
            String type = element.getAttribute("type");

            System.out.println("name=" + name + "  type=" + type);

            new XMLReader() {

                @Override
                public void dealElment(Element element, int index) {
                    String id = element.getAttribute("id");
                    String value = element.getAttribute("value");

                    System.out.println("\tid=" + id + "  value=" + value);
                }
            }.parse(element, "parameter");
        }
    }.parse(XMLReader.openDocument("/test.xml"), "class");
}

结果如下