Java操作XML文件(2)-读取XML文件

package xml;

import java.util.ArrayList;
import java.util.List;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

public class XMLReader {
private String fileName;

public XMLReader(String fileName) {
this.fileName = fileName;
}

public Element getRootElement() throws Exception {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(fileName);
return document.getDocumentElement();
}

public List<Element> getElementsByTagName(Element parent, String tagName) {
List<Element> elements = new ArrayList<Element>();
if (parent != null) {
NodeList list = parent.getElementsByTagName(tagName);
for (int i = 0; i < list.getLength(); i++) {
elements.add((Element) list.item(i));
}
}
return elements;
}

public Element getElementByTagName(Element parent, String tagName, int index) {
List<Element> elements = getElementsByTagName(parent, tagName);
if (index < 0 || index >= elements.size()) {
return elements.get(0);
} else {
return elements.get(index);
}
}

public String getTextContent(Element e) {
return e.getTextContent();
}

public String getAttribute(Element e, String name) {
return e.getAttribute(name);
}

public static void main(String[] args) {
try {
XMLReader reader = new XMLReader("E:\\test.xml");
Element root = reader.getRootElement();
System.out
.println(reader.getElementsByTagName(root, "Book").size());
Element book = reader.getElementByTagName(root, "Book", 0);
Element price = reader.getElementByTagName(book, "Price", 0);
System.out.println(price.getTextContent());
Element title = reader.getElementByTagName(book, "Title", 0);
System.out.println(reader.getTextContent(title));
System.out.println(reader.getAttribute(title, "Auth"));
} catch (Exception e) {
e.printStackTrace();
}

}
}