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java剖析xml的示例代码汇总【XML教程】,java,xml

作者:搜教程发布时间:2019-11-27分类:XML教程浏览:88评论:0


导读:【弁言】现在在Java中用于剖析XML的手艺很多,主流的有DOM、SAX、JDOM、DOM4j,下文重要引见这4种剖析XML文档手艺的运用、优瑕玷及机能测试。一、【基本知识...

【弁言】

现在在Java中用于剖析XML的手艺很多,主流的有DOM、SAX、JDOM、DOM4j,下文重要引见这4种剖析XML文档手艺的运用、优瑕玷及机能测试。

一、【基本知识——扫盲】

sax、dom是两种对xml文档举行剖析的要领(没有细致完成,只是接口),所以只需它们是没法剖析xml文档的;jaxp只是api,它进一步封装了sax、dom两种接口,而且供应了DomcumentBuilderFactory/DomcumentBuilder和SAXParserFactory/SAXParser(默许运用xerces诠释器)。

二、【DOM、SAX、JDOM、DOM4j简朴运用引见】

1、【DOM(Document Object Model) 】
由W3C供应的接口,它将全部XML文档读入内存,构建一个DOM树来对各个节点(Node)举行操纵。
示例代码:

<?xml version="1.0" encoding="UTF-8"?>  
<university name="pku">  
    <college name="c1">  
        <class name="class1">  
            <student name="stu1" sex='male' age="21" />  
            <student name="stu2" sex='female' age="20" />  
            <student name="stu3" sex='female' age="20" />  
        </class>  
        <class name="class2">  
            <student name="stu4" sex='male' age="19" />  
            <student name="stu5" sex='female' age="20" />  
            <student name="stu6" sex='female' age="21" />  
        </class>  
    </college>  
    <college name="c2">  
        <class name="class3">  
            <student name="stu7" sex='male' age="20" />  
        </class>  
    </college>  
    <college name="c3">  
    </college>  
</university>

后文代码中有运用到text.xml(该文档放在src途径下,既编译后在classes途径下),都是指该xml文档。

package test.xml;  
  
import java.io.File;  
import java.io.FileNotFoundException;  
import java.io.FileOutputStream;  
import java.io.IOException;  
import java.io.InputStream;  
  
import javax.xml.parsers.DocumentBuilder;  
import javax.xml.parsers.DocumentBuilderFactory;  
import javax.xml.parsers.ParserConfigurationException;  
import javax.xml.transform.Transformer;  
import javax.xml.transform.TransformerConfigurationException;  
import javax.xml.transform.TransformerException;  
import javax.xml.transform.TransformerFactory;  
import javax.xml.transform.dom.DOMSource;  
import javax.xml.transform.stream.StreamResult;  
  
import org.w3c.dom.Document;  
import org.w3c.dom.Element;  
import org.w3c.dom.Node;  
import org.w3c.dom.NodeList;  
import org.w3c.dom.Text;  
import org.xml.sax.SAXException;  
  
/** 
 * dom读写xml 
 * @author whwang 
 */  
public class TestDom {  
      
    public static void main(String[] args) {  
        read();  
        //write();   
    }  
      
    public static void read() {  
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
        try {  
            DocumentBuilder builder = dbf.newDocumentBuilder();  
            InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.parse(in);  
            // root <university>   
            Element root = doc.getDocumentElement();  
            if (root == null) return;  
            System.err.println(root.getAttribute("name"));  
            // all college node   
            NodeList collegeNodes = root.getChildNodes();  
            if (collegeNodes == null) return;  
            for(int i = 0; i < collegeNodes.getLength(); i++) {  
                Node college = collegeNodes.item(i);  
                if (college != null && college.getNodeType() == Node.ELEMENT_NODE) {  
                    System.err.println("\t" + college.getAttributes().getNamedItem("name").getNodeValue());  
                    // all class node   
                    NodeList classNodes = college.getChildNodes();  
                    if (classNodes == null) continue;  
                    for (int j = 0; j < classNodes.getLength(); j++) {  
                        Node clazz = classNodes.item(j);  
                        if (clazz != null && clazz.getNodeType() == Node.ELEMENT_NODE) {  
                            System.err.println("\t\t" + clazz.getAttributes().getNamedItem("name").getNodeValue());  
                            // all student node   
                            NodeList studentNodes = clazz.getChildNodes();  
                            if (studentNodes == null) continue;  
                            for (int k = 0; k < studentNodes.getLength(); k++) {  
                                Node student = studentNodes.item(k);  
                                if (student != null && student.getNodeType() == Node.ELEMENT_NODE) {  
                                    System.err.print("\t\t\t" + student.getAttributes().getNamedItem("name").getNodeValue());  
                                    System.err.print(" " + student.getAttributes().getNamedItem("sex").getNodeValue());  
                                    System.err.println(" " + student.getAttributes().getNamedItem("age").getNodeValue());  
                                }  
                            }  
                        }  
                    }  
                }  
            }  
        } catch (ParserConfigurationException e) {  
            e.printStackTrace();  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        } catch (SAXException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
          
    }  
      
    public static void write() {  
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
        try {  
            DocumentBuilder builder = dbf.newDocumentBuilder();  
            InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.parse(in);  
            // root <university>   
            Element root = doc.getDocumentElement();  
            if (root == null) return;  
            // 修正属性   
            root.setAttribute("name", "tsu");  
            NodeList collegeNodes = root.getChildNodes();  
            if (collegeNodes != null) {  
                for (int i = 0; i <collegeNodes.getLength() - 1; i++) {  
                    // 删除节点   
                    Node college = collegeNodes.item(i);  
                    if (college.getNodeType() == Node.ELEMENT_NODE) {  
                        String collegeName = college.getAttributes().getNamedItem("name").getNodeValue();  
                        if ("c1".equals(collegeName) || "c2".equals(collegeName)) {  
                            root.removeChild(college);  
                        } else if ("c3".equals(collegeName)) {  
                            Element newChild = doc.createElement("class");  
                            newChild.setAttribute("name", "c4");  
                            college.appendChild(newChild);  
                        }  
                    }  
                }  
            }  
            // 新增节点   
            Element addCollege = doc.createElement("college");  
            addCollege.setAttribute("name", "c5");  
            root.appendChild(addCollege);  
            Text text = doc.createTextNode("text");  
            addCollege.appendChild(text);  
              
            // 将修正后的文档保存到文件   
            TransformerFactory transFactory = TransformerFactory.newInstance();  
            Transformer transFormer = transFactory.newTransformer();  
            DOMSource domSource = new DOMSource(doc);  
            File file = new File("src/dom-modify.xml");  
            if (file.exists()) {  
                file.delete();  
            }  
            file.createNewFile();  
            FileOutputStream out = new FileOutputStream(file);           
            StreamResult xmlResult = new StreamResult(out);  
            transFormer.transform(domSource, xmlResult);  
            System.out.println(file.getAbsolutePath());  
        } catch (ParserConfigurationException e) {  
            e.printStackTrace();  
        } catch (SAXException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        } catch (TransformerConfigurationException e) {  
            e.printStackTrace();  
        } catch (TransformerException e) {  
            e.printStackTrace();  
        }  
    }  
}

该代码只需稍做修正,即可变得越发简约,无需一直写if来推断是不是有子节点。

2、【SAX (Simple API for XML) 】
SAX不必将全部文档加载到内存,基于事宜驱动的API(Observer形式),用户只须要注册本身感兴趣的事宜即可。SAX供应EntityResolver, DTDHandler, ContentHandler, ErrorHandler接口,离别用于监听剖析实体事宜、DTD处置惩罚事宜、正文处置惩罚事宜和处置惩罚失足事宜,与AWT相似,SAX还供应了一个对这4个接口默许的类DefaultHandler(这里的默许完成,实在就是一个空要领),平常只需继续DefaultHandler,重写本身感兴趣的事宜即可。
示例代码:

package test.xml;  
  
import java.io.IOException;  
import java.io.InputStream;  
  
import javax.xml.parsers.ParserConfigurationException;  
import javax.xml.parsers.SAXParser;  
import javax.xml.parsers.SAXParserFactory;  
  
import org.xml.sax.Attributes;  
import org.xml.sax.InputSource;  
import org.xml.sax.Locator;  
import org.xml.sax.SAXException;  
import org.xml.sax.SAXParseException;  
import org.xml.sax.helpers.DefaultHandler;  
  
/** 
 * 
 * @author whwang 
 */  
public class TestSAX {  
  
    public static void main(String[] args) {  
        read();  
        write();  
    }  
      
    public static void read() {  
        try {  
            SAXParserFactory factory = SAXParserFactory.newInstance();  
            SAXParser parser = factory.newSAXParser();  
            InputStream in = TestSAX.class.getClassLoader().getResourceAsStream("test.xml");  
            parser.parse(in, new MyHandler());  
        } catch (ParserConfigurationException e) {  
            e.printStackTrace();  
        } catch (SAXException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
      
    public static void write() {  
        System.err.println("纯SAX关于写操纵无计可施");  
    }  
      
}  
  
// 重写对本身感兴趣的事宜处置惩罚要领   
class MyHandler extends DefaultHandler {  
  
    @Override  
    public InputSource resolveEntity(String publicId, String systemId)  
            throws IOException, SAXException {  
        return super.resolveEntity(publicId, systemId);  
    }  
  
    @Override  
    public void notationDecl(String name, String publicId, String systemId)  
            throws SAXException {  
        super.notationDecl(name, publicId, systemId);  
    }  
  
    @Override  
    public void unparsedEntityDecl(String name, String publicId,  
            String systemId, String notationName) throws SAXException {  
        super.unparsedEntityDecl(name, publicId, systemId, notationName);  
    }  
  
    @Override  
    public void setDocumentLocator(Locator locator) {  
        super.setDocumentLocator(locator);  
    }  
  
    @Override  
    public void startDocument() throws SAXException {  
        System.err.println("最先剖析文档");  
    }  
  
    @Override  
    public void endDocument() throws SAXException {  
        System.err.println("剖析完毕");  
    }  
  
    @Override  
    public void startPrefixMapping(String prefix, String uri)  
            throws SAXException {  
        super.startPrefixMapping(prefix, uri);  
    }  
  
    @Override  
    public void endPrefixMapping(String prefix) throws SAXException {  
        super.endPrefixMapping(prefix);  
    }  
  
    @Override  
    public void startElement(String uri, String localName, String qName,  
            Attributes attributes) throws SAXException {  
        System.err.print("Element: " + qName + ", attr: ");  
        print(attributes);  
    }  
  
    @Override  
    public void endElement(String uri, String localName, String qName)  
            throws SAXException {  
        super.endElement(uri, localName, qName);  
    }  
  
    @Override  
    public void characters(char[] ch, int start, int length)  
            throws SAXException {  
        super.characters(ch, start, length);  
    }  
  
    @Override  
    public void ignorableWhitespace(char[] ch, int start, int length)  
            throws SAXException {  
        super.ignorableWhitespace(ch, start, length);  
    }  
  
    @Override  
    public void processingInstruction(String target, String data)  
            throws SAXException {  
        super.processingInstruction(target, data);  
    }  
  
    @Override  
    public void skippedEntity(String name) throws SAXException {  
        super.skippedEntity(name);  
    }  
  
    @Override  
    public void warning(SAXParseException e) throws SAXException {  
        super.warning(e);  
    }  
  
    @Override  
    public void error(SAXParseException e) throws SAXException {  
        super.error(e);  
    }  
  
    @Override  
    public void fatalError(SAXParseException e) throws SAXException {  
        super.fatalError(e);  
    }  
      
    private void print(Attributes attrs) {  
        if (attrs == null) return;  
        System.err.print("[");  
        for (int i = 0; i < attrs.getLength(); i++) {  
            System.err.print(attrs.getQName(i) + " = " + attrs.getValue(i));  
            if (i != attrs.getLength() - 1) {  
                System.err.print(", ");  
            }  
        }  
        System.err.println("]");  
    }  
}

3、【JDOM】
JDOM与DOM异常相似,它是处置惩罚XML的纯JAVA API,API大批运用了Collections类,且JDOM仅运用细致类而不运用接口。 JDOM 它本身不包含剖析器。它一般运用 SAX2 剖析器来剖析和考证输入 XML 文档(只管它还能够将之前组织的 DOM 示意作为输入)。它包含一些转换器以将 JDOM 示意输出成 SAX2 事宜流、DOM 模子或 XML 文本文档
示例代码:

package test.xml;  
  
import java.io.File;  
import java.io.FileOutputStream;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.List;  
  
import org.jdom.Attribute;  
import org.jdom.Document;  
import org.jdom.Element;  
import org.jdom.JDOMException;  
import org.jdom.input.SAXBuilder;  
import org.jdom.output.XMLOutputter;  
  
/** 
 * JDom读写xml 
 * @author whwang 
 */  
public class TestJDom {  
    public static void main(String[] args) {  
        //read();   
        write();  
    }  
      
    public static void read() {  
        try {  
            boolean validate = false;  
            SAXBuilder builder = new SAXBuilder(validate);  
            InputStream in = TestJDom.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.build(in);  
            // 猎取根节点 <university>   
            Element root = doc.getRootElement();  
            readNode(root, "");  
        } catch (JDOMException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
      
    @SuppressWarnings("unchecked")  
    public static void readNode(Element root, String prefix) {  
        if (root == null) return;  
        // 猎取属性   
        List<Attribute> attrs = root.getAttributes();  
        if (attrs != null && attrs.size() > 0) {  
            System.err.print(prefix);  
            for (Attribute attr : attrs) {  
                System.err.print(attr.getValue() + " ");  
            }  
            System.err.println();  
        }  
        // 猎取他的子节点   
        List<Element> childNodes = root.getChildren();  
        prefix += "\t";  
        for (Element e : childNodes) {  
            readNode(e, prefix);  
        }  
    }  
      
    public static void write() {  
        boolean validate = false;  
        try {  
            SAXBuilder builder = new SAXBuilder(validate);  
            InputStream in = TestJDom.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.build(in);  
            // 猎取根节点 <university>   
            Element root = doc.getRootElement();  
            // 修正属性   
            root.setAttribute("name", "tsu");  
            // 删除   
            boolean isRemoved = root.removeChildren("college");  
            System.err.println(isRemoved);  
            // 新增   
            Element newCollege = new Element("college");  
            newCollege.setAttribute("name", "new_college");  
            Element newClass = new Element("class");  
            newClass.setAttribute("name", "ccccc");  
            newCollege.addContent(newClass);  
            root.addContent(newCollege);  
            XMLOutputter out = new XMLOutputter();  
            File file = new File("src/jdom-modify.xml");  
            if (file.exists()) {  
                file.delete();  
            }  
            file.createNewFile();  
            FileOutputStream fos = new FileOutputStream(file);  
            out.output(doc, fos);  
        } catch (JDOMException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
      
}

4、【DOM4j】
dom4j是现在在xml剖析方面是最优异的(Hibernate、Sun的JAXM也都运用dom4j来剖析XML),它兼并了很多超越基本 XML 文档示意的功用,包含集成的 XPath 支撑、XML Schema 支撑以及用于大文档或流化文档的基于事宜的处置惩罚
示例代码:

package test.xml;  
  
import java.io.File;  
import java.io.FileWriter;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.List;  
  
import org.dom4j.Attribute;  
import org.dom4j.Document;  
import org.dom4j.DocumentException;  
import org.dom4j.DocumentHelper;  
import org.dom4j.Element;  
import org.dom4j.ProcessingInstruction;  
import org.dom4j.VisitorSupport;  
import org.dom4j.io.SAXReader;  
import org.dom4j.io.XMLWriter;  
  
/** 
 * Dom4j读写xml 
 * @author whwang 
 */  
public class TestDom4j {  
    public static void main(String[] args) {  
        read1();  
        //read2();   
        //write();   
    }  
  
    public static void read1() {  
        try {  
            SAXReader reader = new SAXReader();  
            InputStream in = TestDom4j.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = reader.read(in);  
            Element root = doc.getRootElement();  
            readNode(root, "");  
        } catch (DocumentException e) {  
            e.printStackTrace();  
        }  
    }  
      
    @SuppressWarnings("unchecked")  
    public static void readNode(Element root, String prefix) {  
        if (root == null) return;  
        // 猎取属性   
        List<Attribute> attrs = root.attributes();  
        if (attrs != null && attrs.size() > 0) {  
            System.err.print(prefix);  
            for (Attribute attr : attrs) {  
                System.err.print(attr.getValue() + " ");  
            }  
            System.err.println();  
        }  
        // 猎取他的子节点   
        List<Element> childNodes = root.elements();  
        prefix += "\t";  
        for (Element e : childNodes) {  
            readNode(e, prefix);  
        }  
    }  
      
    public static void read2() {  
        try {  
            SAXReader reader = new SAXReader();  
            InputStream in = TestDom4j.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = reader.read(in);  
            doc.accept(new MyVistor());  
        } catch (DocumentException e) {  
            e.printStackTrace();  
        }  
    }  
      
    public static void write() {  
        try {  
            // 建立一个xml文档   
            Document doc = DocumentHelper.createDocument();  
            Element university = doc.addElement("university");  
            university.addAttribute("name", "tsu");  
            // 解释   
            university.addComment("这个是根节点");  
            Element college = university.addElement("college");  
            college.addAttribute("name", "cccccc");  
            college.setText("text");  
              
            File file = new File("src/dom4j-modify.xml");  
            if (file.exists()) {  
                file.delete();  
            }  
            file.createNewFile();  
            XMLWriter out = new XMLWriter(new FileWriter(file));  
            out.write(doc);  
            out.flush();  
            out.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
}  
  
class MyVistor extends VisitorSupport {  
    public void visit(Attribute node) {  
        System.out.println("Attibute: " + node.getName() + "="  
                + node.getValue());  
    }  
  
    public void visit(Element node) {  
        if (node.isTextOnly()) {  
            System.out.println("Element: " + node.getName() + "="  
                    + node.getText());  
        } else {  
            System.out.println(node.getName());  
        }  
    }  
  
    @Override  
    public void visit(ProcessingInstruction node) {  
        System.out.println("PI:" + node.getTarget() + " " + node.getText());  
    }  
}

三、【机能测试】

环境:AMD4400+ 2.0+GHz主频 JDK6.0
运转参数:-Xms400m -Xmx400m
xml文件大小:10.7M
效果:
DOM: >581297ms
SAX: 8829ms
JDOM: 581297ms
DOM4j: 5309ms
时候包含IO的,只是举行了简朴的测试,仅供参考!!!!

四、【对照】

1、【DOM】
DOM是基于树的构造,一般须要加载整文档和组织DOM树,然后才最先事情。
长处:
a、因为整棵树在内存中,因而能够对xml文档随机接见
b、能够对xml文档举行修正操纵
c、较sax,dom运用也更简朴。
瑕玷:
a、全部文档必需一次性剖析完
a、因为全部文档都须要载入内存,关于大文档本钱高
2、【SAX】
SAX相似流媒体,它基于事宜驱动的,因而无需将全部文档载入内存,运用者只须要监听本身感兴趣的事宜即可。
长处:
a、无需将全部xml文档载入内存,因而斲丧内存少
b、能够注册多个ContentHandler
瑕玷:
a、不能随机的接见xml中的节点
b、不能修正文档
3、【JDOM】
JDOM是纯Java的处置惩罚XML的API,其API中大批运用Collections类,
长处:
a、DOM体式格局的长处
b、具有SAX的Java划定规矩
瑕玷
a、DOM体式格局的瑕玷
4、【DOM4J】
这4中xml剖析体式格局中,最优异的一个,集易用和机能于一身。

五、【小插曲XPath】

XPath 是一门在 XML 文档中查找信息的言语, 可用来在 XML 文档中对元素和属性举行遍历。XPath 是 W3C XSLT 规范的重要元素,而且 XQuery 和 XPointer 同时被构建于 XPath 表达之上。因而,对 XPath 的明白是很多高等 XML 运用的基本。
XPath异常相似对数据库操纵的SQL言语,或者说JQuery,它能够轻易开发者抓起文档中须要的东西。(dom4j也支撑xpath)
示例代码:

package test.xml;  
  
import java.io.IOException;  
import java.io.InputStream;  
  
import javax.xml.parsers.DocumentBuilder;  
import javax.xml.parsers.DocumentBuilderFactory;  
import javax.xml.parsers.ParserConfigurationException;  
import javax.xml.xpath.XPath;  
import javax.xml.xpath.XPathConstants;  
import javax.xml.xpath.XPathExpression;  
import javax.xml.xpath.XPathExpressionException;  
import javax.xml.xpath.XPathFactory;  
  
import org.w3c.dom.Document;  
import org.w3c.dom.NodeList;  
import org.xml.sax.SAXException;  
  
public class TestXPath {  
  
    public static void main(String[] args) {  
        read();  
    }  
      
    public static void read() {  
        try {  
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
            DocumentBuilder builder = dbf.newDocumentBuilder();  
            InputStream in = TestXPath.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.parse(in);  
            XPathFactory factory = XPathFactory.newInstance();  
            XPath xpath = factory.newXPath();  
            // 拔取一切class元素的name属性   
            // XPath语法引见: http://w3school.com.cn/xpath/   
            XPathExpression expr = xpath.compile("//class/@name");  
            NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);  
            for (int i = 0; i < nodes.getLength(); i++) {  
                System.out.println("name = " + nodes.item(i).getNodeValue());  
                    }  
        } catch (XPathExpressionException e) {  
            e.printStackTrace();  
        } catch (ParserConfigurationException e) {  
            e.printStackTrace();  
        } catch (SAXException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
      
}

六、【补充】

注重4种剖析要领对TextNode(文本节点)的处置惩罚:

1、在运用DOM时,挪用node.getChildNodes()猎取该节点的子节点,文本节点也会被看成一个Node来返回,如:

<?xml version="1.0" encoding="UTF-8"?>  
<university name="pku">  
    <college name="c1">  
        <class name="class1">  
            <student name="stu1" sex='male' age="21" />  
            <student name="stu2" sex='female' age="20" />  
            <student name="stu3" sex='female' age="20" />  
        </class>  
    </college>  
</university>
package test.xml;  
  
import java.io.FileNotFoundException;  
import java.io.IOException;  
import java.io.InputStream;  
import java.util.Arrays;  
  
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.Node;  
import org.w3c.dom.NodeList;  
import org.xml.sax.SAXException;  
  
/** 
 * dom读写xml 
 * @author whwang 
 */  
public class TestDom2 {  
      
    public static void main(String[] args) {  
        read();  
    }  
      
    public static void read() {  
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  
        try {  
            DocumentBuilder builder = dbf.newDocumentBuilder();  
            InputStream in = TestDom2.class.getClassLoader().getResourceAsStream("test.xml");  
            Document doc = builder.parse(in);  
            // root <university>   
            Element root = doc.getDocumentElement();  
            if (root == null) return;  
//          System.err.println(root.getAttribute("name"));   
            // all college node   
            NodeList collegeNodes = root.getChildNodes();  
            if (collegeNodes == null) return;  
            System.err.println("university子节点数:" + collegeNodes.getLength());  
            System.err.println("子节点以下:");  
            for(int i = 0; i < collegeNodes.getLength(); i++) {  
                Node college = collegeNodes.item(i);  
                if (college == null) continue;  
                if (college.getNodeType() == Node.ELEMENT_NODE) {  
                    System.err.println("\t元素节点:" + college.getNodeName());  
                } else if (college.getNodeType() == Node.TEXT_NODE) {  
                    System.err.println("\t文本节点:" + Arrays.toString(college.getTextContent().getBytes()));  
                }  
            }  
        } catch (ParserConfigurationException e) {  
            e.printStackTrace();  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        } catch (SAXException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
          
    }  
}

输出的效果是:

university子节点数:3  
子节点以下:  
    文本节点:[10, 9]  
    元素节点:college  
    文本节点:[10]


个中\n的ASCII码为10,\t的ASCII码为9。效果让人大吃一惊,university的子节点数不是1,也不是2,而是3,这3个子节点都是谁呢?为了看得更清晰点,把xml文档改成:

<?xml version="1.0" encoding="UTF-8"?>  
<university name="pku">11  
    <college name="c1">  
        <class name="class1">  
            <student name="stu1" sex='male' age="21" />  
            <student name="stu2" sex='female' age="20" />  
            <student name="stu3" sex='female' age="20" />  
        </class>  
    </college>22  
</university>

照样上面的顺序,输出效果为:

university子节点数:3  
子节点以下:  
    文本节点:[49, 49, 10, 9]  
    元素节点:college  
    文本节点:[50, 50, 10]

个中数字1的ASCII码为49,数字2的ASCII码为50。

2、运用SAX来剖析同DOM,当你重写它的public void characters(char[] ch, int start, int length)要领时,你就可以看到。

3、JDOM,挪用node.getChildren()只返回子节点,不包含TextNode节点(不论该节点是不是有Text信息)。假如要猎取该节点的Text信息,能够挪用node.getText()要领,该要领返回节点的Text信息,也包含\n\t等特别字符。

4、DOM4j同JDOM

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