利用java Api解析XML

import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;

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

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Usage: You can get a instance of Document from a string of xml.
 * This class supply some method to read a document.
 *
 */
public class XMLParser {

 /**
  * Get a instance of Document from a string of xml.
  *
  * @param xmlStr
  * @return Document
  */
 public static Document parse(String xmlStr) {
  if (xmlStr == null) {
   return null;
  }
  StringReader reader = new StringReader(xmlStr);
  InputSource source = new InputSource(reader);
  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
  DocumentBuilder builder = null;

  try {
   builder = factory.newDocumentBuilder();
   
  } catch (ParserConfigurationException e) {
   e.printStackTrace();
  }
  if(builder == null){
   return null;
  }
  Document doc = null;
  try {
   doc = builder.parse(source);
  } catch (SAXException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  return doc;
 }

 
 /**
  * Get Item Value.
  * @param node
  * @return String
  */
 public static String getItemValue(Node node){
  String value = "";
  if(node == null){
   return null;
  }
  node = node.getFirstChild();
  if(node != null){
   value = node.getNodeValue();
  }
  return value.trim();
 }
 
 /**
  * Get Simple Node's Value
  *
  * @param list
  * @return String
  */
 public static String getSimpleNodeValue(NodeList list){
  String value = "";
  Node node = null;
  if (list != null) {
   node = list.item(0);
   value = getItemValue(node);
  }
  return value.trim();
 }
 
 /**
  * Get Children.
  * @param list
  * @return List<Node>
  */
 public static List<Node> getChildren(NodeList list){
  List<Node> children = new ArrayList<Node>();
  Node node = null;
  if(list == null){
   return children;
  }
  for(int i= 0; i< list.getLength(); i++){
   node = list.item(i);
   if (node.getNodeType() == Node.ELEMENT_NODE) {
    children.add(node);
   }
  }
  return children;
 }

 
 /**
  * Get Attribute Value
  * @param node
  * @param name
  * @return String
  * @throws Exception
  */
 public static String getAttributeValue(Node node, String name) throws Exception{
  String value = "";
  if(node == null){
   throw new Exception("Node is null!");
  }
  NamedNodeMap nnm = node.getAttributes();
  if (nnm == null) {
   throw new Exception("NamedNodeMap is null!");
  }
  Node item = nnm.getNamedItem(name);
  if (item == null) {
   throw new Exception("No such attribute.");
  }
  value = item.getNodeValue();
  return value.trim();
 }
 
}