XML读写操作之DOM

 *DOM为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档， 然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。
 * 优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能
 * 缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；
 * 使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、CPU）。

1.新建一个接口类

package com.wepull.xml2;

public interface XmlDocument {
	/** 
	* 建立XML文档 
	* @param fileName 文件全路径名称 
	*/ 
	public void createXml(String fileName); 
	/** 
	* 解析XML文档 
	* @param fileName 文件全路径名称 
	*/ 
	public void parserXml(String fileName); 

}

2.新建一个实现类

package com.wepull.xml2;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
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.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.xml.sax.SAXException;

public class DomDemo implements XmlDocument {
	private Document document;
	private String fileName;
	public void init() {
		try {
			DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
			DocumentBuilder builder = factory.newDocumentBuilder();
			this.document = builder.newDocument();
		} catch (ParserConfigurationException e) {
			System.out.println(e.getMessage());
		}
	}

	public void createXml(String fileName) {
		Element root = this.document.createElement("employees");
		this.document.appendChild(root);
		Element employee = this.document.createElement("employee");
		Element name = this.document.createElement("name");
		name.appendChild(this.document.createTextNode("丁宏亮"));
		employee.appendChild(name);
		Element sex = this.document.createElement("sex");
		sex.appendChild(this.document.createTextNode("m"));
		employee.appendChild(sex);
		Element age = this.document.createElement("age");
		age.appendChild(this.document.createTextNode("30"));
		employee.appendChild(age);
		root.appendChild(employee);

		TransformerFactory tf = TransformerFactory.newInstance();
		try {
			Transformer transformer = tf.newTransformer();
			DOMSource source = new DOMSource(document);
			transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");
			transformer.setOutputProperty(OutputKeys.INDENT, "yes");
			PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));
			StreamResult result = new StreamResult(pw);
			transformer.transform(source, result);
			System.out.println("生成XML文件成功!");
		} catch (TransformerConfigurationException e) {

			System.out.println(e.getMessage());
		} catch (IllegalArgumentException e) {

			System.out.println(e.getMessage());
		} catch (FileNotFoundException e) {

			System.out.println(e.getMessage());
		} catch (TransformerException e) {

			System.out.println(e.getMessage());
		}

	}

	public void parserXml(String fileName) {
		try {
			DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
			DocumentBuilder db = dbf.newDocumentBuilder();
			Document document = db.parse(fileName);
			NodeList employees = document.getChildNodes();
			for (int i = 0; i < employees.getLength(); i++) {
				Node employee = employees.item(i);
				NodeList employeeInfo = employee.getChildNodes();
				for (int j = 0; j < employeeInfo.getLength(); j++) {
					Node node = employeeInfo.item(j);
					NodeList employeeMeta = node.getChildNodes();
					for (int k = 0; k < employeeMeta.getLength(); k++) {
						System.out.println(employeeMeta.item(k).getNodeName()
								+ ":" + employeeMeta.item(k).getTextContent());
					}
				}
			}
			System.out.println("解析完毕");
		} catch (FileNotFoundException e) {
			System.out.println(e.getMessage());
		} catch (ParserConfigurationException e) {
			System.out.println(e.getMessage());
		} catch (SAXException e) {
			System.out.println(e.getMessage());
		} catch (IOException e) {
			System.out.println(e.getMessage());
		}
	}

}

3.新建一个xml文件，命名为book.xml

<?xml version="1.0" encoding="UTF-8"?>
<books>  
    <book id="12">  
        <name>thinking in java</name>  
        <price>85.5</price>  
    </book>  
    <book id="15">  
        <name>Spring in Action</name>  
        <price>39.0</price>  
    </book>  
    <other>
    	<driver>aaa</driver>
    	<url>bbb</url>
    </other>
</books>  

 

4.新建一个测试类

package com.wepull.xml2;

/**
 * 测试四种xml解析方式
 */
public class TestXML {
	public static void main(String[] args) {
		XmlDocument test = new DomDemo();
		
		String path = "D:/wepull/TestXML/src/book.xml";
		String path2= "D:/wepull/TestXML/src/test.xml";
		test.parserXml(path);
		test.createXml(path2);
	}
}

5.运行并测试

你会发现当前目录下回生成一个为test.xml的文件

控制台上会打印出解析book.xml的内容