【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("	id=" + id + "  value=" + value);
                }
            }.parse(element, "parameter");
        }
    }.parse(XMLReader.openDocument("/test.xml"), "class");
}

结果如下