入口测试类：

注：class 有很多方法需看java的api

package priv.yingmm.main;

import java.io.ByteArrayInputStream;
import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;

import priv.yingmm.entity.Area;

/**
 * @Description: xml生成测试类
 * @ClassName: ReflexTest
 * @author yingmm
 * @date 2015-5-2 下午08:53:21
 * 
 */
public class ReflexTest {

	public static void main(String[] args) throws Exception {
		/**S 测试数据*/
		List<Area> areaList = new ArrayList<Area>();
		for (int i = 0; i < 10; i++) {
			areaList.add(new Area("33022" + i,"宁波市",3000));
		}
		/**E 测试数据*/
		/**S 生成xml和写入数据*/
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
		DocumentBuilder db = dbf.newDocumentBuilder();
		String parseStr = ReflexTest.parseStr(areaList);
		Document document = db.parse(new ByteArrayInputStream(parseStr.getBytes()));
		TransformerFactory tf = TransformerFactory.newInstance();
		Transformer t = tf.newTransformer();
		t.setOutputProperty("encoding","utf-8");
		DOMSource doms = new DOMSource(document.getDocumentElement());
		StreamResult sr = new StreamResult(new FileOutputStream("area.xml"));
		t.transform(doms,sr);
		/**E 生成xml和写入数据*/
		
		
	}

	/**
	 * @param 集合拼接转换成字符串
	 * @author yingmm
	 * @throws Exception
	 */
	private static String parseStr(List list) throws Exception {
		// TODO Auto-generated method stub

		StringBuffer sb = new StringBuffer();
		sb.append("<areas>");
		for (int i = 0; i < list.size(); i++) {

			@SuppressWarnings("rawtypes")
			Class cl = list.get(i).getClass();
			Field[] f = cl.getDeclaredFields();
			sb.append("<area");
			sb.append(" id=\""+ cl.getMethod("getAreaCode",new Class[] {})
					.invoke(list.get(i),new Class[] {}) + "\">");
			for (int j = 0; j < f.length; j++) {
				if ("areaCode".equals(f[j].getName())) {
					continue;
				}
				f[j].setAccessible(true);
				sb.append("<" + f[j].getName() + ">");
				sb.append(f[j].get(list.get(i)));
				sb.append("</" + f[j].getName() + ">");
				f[j].setAccessible(false);
			}
			sb.append("</area>");
		}
		sb.append("</areas>");
		return sb.toString();
	}

}

package priv.yingmm.entity;

/**
 * @Description: 区域类
 * @ClassName: Area
 * @author yingmm
 * @date 2015-5-2 下午08:05:53
 * 
 */
public class Area {

	private String areaCode;
	private String areaName;
	private int personNum;

	// private String city;

	public Area() {
		super();
	}

	public Area(String areaCode,String areaName,int personNum) {
		super();
		this.areaCode = areaCode;
		this.areaName = areaName;
		this.personNum = personNum;
	}

	public String getAreaCode() {
		return areaCode;
	}

	public void setAreaCode(String areaCode) {
		this.areaCode = areaCode;
	}

	public String getAreaName() {
		return areaName;
	}

	public void setAreaName(String areaName) {
		this.areaName = areaName;
	}

	public int getPersonNum() {
		return personNum;
	}

	public void setPersonNum(int personNum) {
		this.personNum = personNum;
	}

}