DOM方式解析xml文件

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

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 com.safetys.customerform.xml.model.Area;

/**
 * 
 * @author hehc
 *
 */
public class AreaUtil {
	
	public static final String FROM_XML = "xml";
	
	private String from = FROM_XML;
	
	private String xmlFileDirectory;
	
	private Map<String,Area> areaMap = new HashMap<String, Area>(); // provinceCode, provinceArea
	
	private AreaUtil(){
		super();
	}
	
	public final static AreaUtil getInstance(String FROM, String xmlFileDirectory){
		AreaUtil areaUtil = new AreaUtil();
		areaUtil.setFrom(FROM);
		areaUtil.setXmlFileDirectory(xmlFileDirectory);
		areaUtil.init();
		return areaUtil;
	}
	
	/**
	 * 解析xml文件
	 ********************************************************
	 * template of xml:                                     *
	 * <area name="国家">					                *
	 *   <first-area name="省" code="">			         *
	 *      <second-area name="市" code="">			     *
	 *          <third-area name="区" code=""></third-area> *
	 *      </second-area>					              *
	 *   </first-area>					                  *
	 * </area>	 				                          *
	 ********************************************************
	 */
	private void init(){
		if(from != null && from.equals(AreaUtil.FROM_XML)){
			DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
			try {
				DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
				if(xmlFileDirectory == null)
					throw new Exception("xml文件地址为空！");
				Document doc = documentBuilder.parse(new FileInputStream(xmlFileDirectory));
				Element areaRoot = doc.getDocumentElement();
				// System.out.println(areaRoot.getAttribute("name"));
				
				NodeList firstAreas = areaRoot.getChildNodes();
				Map<String,Area> firstAreaMap = new HashMap<String, Area>();
				for(int i = 0; i < firstAreas.getLength(); i++){//遍历first-area标签
					Area firstArea = new Area();
					Node firstNode = firstAreas.item(i);
					if(firstNode.getNodeType() == Node.ELEMENT_NODE){
						firstArea.setName(firstNode.getAttributes().
								getNamedItem("name").getNodeValue());
						firstArea.setCode(firstNode.getAttributes().
								getNamedItem("code").getNodeValue());
						
						NodeList secondAreas = firstNode.getChildNodes();
						Map<String,Area> secondAreaMap = new HashMap<String, Area>();
						for(int j = 0; j < secondAreas.getLength(); j++){//遍历second-area标签
							Area secondArea = new Area();
							Node secondNode = secondAreas.item(j);
							if(secondNode.getNodeType() == Node.ELEMENT_NODE){
								secondArea.setName(secondNode.getAttributes().
										getNamedItem("name").getNodeValue());
								secondArea.setCode(secondNode.getAttributes().
										getNamedItem("code").getNodeValue());
								
								NodeList thirdAreas = secondNode.getChildNodes();
								Map<String,Area> thirdAreaMap = new HashMap<String, Area>();
								for(int k = 0; k < thirdAreas.getLength(); k++){//遍历third-area标签
									
									Area thirdArea = new Area();
									Node thirdNode = thirdAreas.item(k);
									if(thirdNode.getNodeType() == Node.ELEMENT_NODE){
										thirdArea.setName(thirdNode.getAttributes().
												getNamedItem("name").getNodeValue());
										thirdArea.setCode(thirdNode.getAttributes().
												getNamedItem("code").getNodeValue());
										
										thirdAreaMap.put(thirdArea.getCode(), thirdArea);
									}
								}
								
								secondArea.setAreaMap(thirdAreaMap);
								
								secondAreaMap.put(secondArea.getCode(), secondArea);
							}
						}
						
						firstArea.setAreaMap(secondAreaMap);
						
						firstAreaMap.put(firstArea.getCode(), firstArea);
					}
					
				}
				areaMap = firstAreaMap;
				
			} catch (ParserConfigurationException e) {
				e.printStackTrace();
			} catch (FileNotFoundException e) { 
				e.printStackTrace();
			} catch (Exception e) {
				e.printStackTrace();
			}
		
	    }
	}
	
	/**
	 * 返回当前国家区域的所有下一级(二级)行政单位（中国：省）
	 * @return Map<String provinceCode, String provinceName>
	 */
	public Map<String, String> getProvinces(){
		Map<String, String> map = new HashMap<String, String>();
		if(areaMap != null && !areaMap.isEmpty()){
			Iterator<String> it = areaMap.keySet().iterator();
			while(it.hasNext()){
				String code = it.next();
				map.put(code, areaMap.get(code).getName());
			}
		}
		return map;
	}
	
	/**
	 * 返回当前国家区域、指定二级行政单位下的所有三级行政单位（中国：市）
	 * @param provinceCode
	 * @return Map<String cityCode, String cityName>
	 */
	public Map<String, String> getCities(String provinceCode){
		Map<String, String> map = new HashMap<String, String>();
		if(areaMap != null & !areaMap.isEmpty()){
			Area firstArea = areaMap.get(provinceCode);
			if(firstArea != null){
				Map<String, Area> secondAreaMap = firstArea.getAreaMap();
				if(secondAreaMap != null && !secondAreaMap.isEmpty()){
					Iterator<String> it = secondAreaMap.keySet().iterator();
					while(it.hasNext()){
						String code = it.next();
						map.put(code, secondAreaMap.get(code).getName());
					}
				}
			}
		}
		return map;
	}
	
	/**
	 * 返回当前国家区域、指定二级行政单位下的所有四级行政单位（中国：区）
	 * @param provinceCode
	 * @param cityCode
	 * @return Map<String regionCode, String regionName>
	 */
	public Map<String, String> getRegions(String provinceCode, String cityCode){
		Map<String, String> map = new HashMap<String, String>();
		if(areaMap != null & !areaMap.isEmpty()){
			
			Area firstArea = areaMap.get(provinceCode);
			if(firstArea != null){
				Map<String,Area> secondAreaMap = firstArea.getAreaMap();
				
				if(secondAreaMap != null && !secondAreaMap.isEmpty()){
					Area secondArea = secondAreaMap.get(cityCode);
					
					if(secondArea != null){
						Map<String, Area> thirdAreaMap = secondArea.getAreaMap();
						if(thirdAreaMap != null && !thirdAreaMap.isEmpty()){
							Iterator<String> it = thirdAreaMap.keySet().iterator();
							while(it.hasNext()){
								String code = it.next();
								map.put(code, thirdAreaMap.get(code).getName());
							}
						}
					}
				}
			}
		}
		return map;
	}
	
	/**
	 * 根据当前国家区域、指定某区域代码获取该区域名称
	 * @param areaCode
	 * @return String
	 */
	public String getAreaName(String areaCode) throws Exception{
		
		if(areaMap != null && !areaMap.isEmpty()){
			Iterator<String> it = areaMap.keySet().iterator();
			while(it.hasNext()){
				String firstCode = it.next();
				if(firstCode.equals(areaCode)){
					return areaMap.get(firstCode).getName();
				}
				
				Map<String, Area> secondAreaMap = areaMap.get(firstCode).getAreaMap();
				if(secondAreaMap != null && !secondAreaMap.isEmpty()){
					Iterator<String> it_ = secondAreaMap.keySet().iterator();
					while(it_.hasNext()){
						String secondCode = it_.next();
						if(secondCode.equals(areaCode)){
							return secondAreaMap.get(secondCode).getName();
						}
						
						Map<String, Area> thirdAreaMap = secondAreaMap.get(secondCode).getAreaMap();
						if(thirdAreaMap != null && !thirdAreaMap.isEmpty()){
							Iterator<String> it__ = thirdAreaMap.keySet().iterator();
							while(it__.hasNext()){
								String thirdCode = it__.next();
								if(thirdCode.equals(areaCode)){
									return thirdAreaMap.get(thirdCode).getName();
								}
							}
						}
					}
				}
			}
			throw new Exception("未知区域");
		}
		return null;
	}

	private void setFrom(String from) {
		this.from = from;
	}

	private void setXmlFileDirectory(String xmlFileDirectory) {
		this.xmlFileDirectory = xmlFileDirectory;
	}