源程序：

package b2b2c;
import java.util.Hashtable;
import java.util.Vector;
import java.util.Enumeration;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.lang.System;
import javax.servlet.*;
import javax.servlet.http.*;

public class CartBean {
Hashtable params=new Hashtable();
Vector items = new Vector();
private static final String DEFAULT_SAX_DRIVER_CLASS ="org.apache.xerces.parsers.SAXParser";
private String saxDriverClass;
private SAXBuilder builder;
private Document doc;
private Element root;  

// 輸出訂單到這個文件
private String xmldoc = "/xml/order.xml";
private String orderNo;
//... JDBC ....
private Connection con;
private PreparedStatement pstmt_update_stock_qty;
private PreparedStatement pstmt_select_stock_qty;
private PreparedStatement pstmt_insert_order;
private PreparedStatement pstmt_insert_orderitem;
//-----------------------------------
public CartBean() { System.out.println("start CartBean."); }
/* // for debug
public static void main(String args[]) {
CatalogBean catalog = new CatalogBean();
CartBean cart = new CartBean();
catalog.startParse();
cart.addItem( catalog.getItem(1) );
cart.addItem( catalog.getItem(2) );
cart.toXML();
}
*/
// 處理網頁傳遞的參數, 存到Hashtable中
public void processRequest(HttpServletRequest req) {
Enumeration en = req.getParameterNames();
while (en.hasMoreElements()) {
String varName = (String)en.nextElement();  
String[] varValues = req.getParameterValues(varName);
if (varValues.length > 1) {
params.put(varName, varValues);
}
else {
params.put(varName, varValues[0]);
System.out.println("req:"+varName+"="+varValues[0]);
}
}
}
public String getParam(String key) {
return (String)params.get(key);
}
public void setParam(String key, String value) {
if (params.containsKey(key))
params.put(key, value);
else
System.out.println("no such key:"+key+" in param Hashtable");
}
public String[] getParamArr(String key) {
return (String[])params.get(key);
}
//...............................................
//.... 起始CartBean的準備工作
public void init() {
// 清除Cart資訊
items.clear();
}
// 加入有輸入購買數量的項目到購物車
public void addItems(Vector items) {
// items為商品目錄的所有項目  

String qtyParamValue;
//int qty;
Item item;
for (int i=0; i<items.size(); i++) {
qtyParamValue = getParam("qty_"+ new Integer(i).toString() );
if (qtyParamValue!=null && !qtyParamValue.equals(""))
{
item= (Item)items.get(i);
item.setQty(qtyParamValue); // String
addItem(item);
}
}
}
// 加入項目到購物車Vector
public void addItem(Item item) {
items.add(item);
// modify warehouse database stock table
if (con == null) {
createConnection();
}
modifyStock(item.getId(), Integer.parseInt(item.getQty()));
System.out.println("item:"+item.getItemname());
}
// 取得購物車內的所有項目
public Vector getItems() {
return items;
}
// 取得購物車內的單一項目
public Item getItem(int index) {
return (Item)items.get(index);  

}
// 取得購物車內的項目數
public int getCartSize() {
return items.size();
}
// 取得訂單編號
public String getOrderno() {
return orderNo;
}
//.... JDBC ......
// 修改庫存資料庫
public void modifyStock(String id, int qty) {
try {
int oldQty = 0;
pstmt_select_stock_qty.setString(1, id);
ResultSet rs = pstmt_select_stock_qty.executeQuery();
if (rs.next()) {
oldQty = rs.getInt(1);
System.out.println("old QTY="+oldQty);
}
int newQty = oldQty - qty;
pstmt_update_stock_qty.setInt(1, newQty);
pstmt_update_stock_qty.setString(2, id);
pstmt_update_stock_qty.executeUpdate();
rs.close();
} catch (SQLException ex) {
System.out.println(ex.toString());
}
catch (Exception ex) {
System.out.println(ex.toString());
}
}
// 修改訂單資料庫
public void modifyOrder(String name, String address)  

{
try {
pstmt_insert_order.setString(1, name);
pstmt_insert_order.setString(2, address);
pstmt_insert_order.setString(3, orderNo);
pstmt_insert_order.executeUpdate();
}
catch (SQLException ex) {
System.out.println(ex.toString());
}
catch (Exception ex) {
System.out.println(ex.toString());
}
}
// 修改訂單項目資料庫
public void modifyOrderItem(Item item)
{
try {
pstmt_insert_orderitem.setString(1, item.getId());
pstmt_insert_orderitem.setInt(2,
Integer.parseInt(item.getQty()));
pstmt_insert_orderitem.setString(3, orderNo);
pstmt_insert_orderitem.executeUpdate();
}
catch (SQLException ex) {
System.out.println(ex.toString());
}
catch (Exception ex) {
System.out.println(ex.toString());
}
}  

// 建立資料庫連結及prepared statement
public void createConnection() {
try {
Class.forName("org.gjt.mm.mysql.Driver").newInstance();
}
catch (Exception E) {
System.err.println("Unable to load driver.");
E.printStackTrace();
}
try {
con = DriverManager.getConnection("jdbc:mysql://localhost/warehouse?user=growbal&password=javaxml");
pstmt_update_stock_qty = con.prepareStatement("update stock set qty=? where id=?");
pstmt_select_stock_qty = con.prepareStatement("select qty from stock where id=?");
pstmt_insert_order = con.prepareStatement("insert into customorder (name, address, orderno) values (?,?,?)");
pstmt_insert_orderitem = con.prepareStatement("insert into customorderitem (id, qty, orderno) values (?,?,?)");
}
catch (SQLException ex) {
System.out.println(ex.toString());
}
catch (Exception ex) {
System.out.println(ex.toString());  

}
}
// 輸出訂單XML到檔案/xml/order.xml, 並關閉資料庫
public void close()
throws IOException, JDOMException {
doc.setRootElement(root);
startOutputXML(new FileOutputStream(xmldoc));
//.... close database .....
try {
pstmt_update_stock_qty.close();
pstmt_select_stock_qty.close();
con.close();
}
catch (SQLException ex) {
System.out.println(ex.toString());
}
catch (Exception ex) {
System.out.println(ex.toString());
}
}
private void startOutputXML(OutputStream out)
throws IOException, JDOMException {
// Create an outputter with default formatting
XMLOutputter outputter = getXMLOutputter();
outputter.output(doc, out);
}
private XMLOutputter getXMLOutputter()
throws IOException, JDOMException {
// Create an outputter with certain encoding
XMLOutputter outputter = new XMLOutputter(" ", true, "Big5");
outputter.setTrimText(true);
outputter.setExpandEmptyElements(true);
return outputter;  

}
// 增加項目到XML文件
private void addToXML(Item item) {
// add one element to XML file
Element curItem = new Element("item");
Element curItemname = new Element("itemname");
curItemname.addContent(item.getItemname());
Element curId = new Element("id");
curId.addContent(item.getId());
Element curQty = new Element("qty");
curQty.addContent(item.getQty());
curItem.addContent(curItemname);
curItem.addContent(curId);
curItem.addContent(curQty);
root.addContent(curItem);
}

// 輸出訂單到XML文件, 並修改資料庫
public void toXML(String name, String address) {
this.saxDriverClass = DEFAULT_SAX_DRIVER_CLASS;
builder = new SAXBuilder(saxDriverClass);
Item item;

// build new XML doc
root = new Element("order");
doc = new Document(root);

// add timestamp as order's serial number
Element elemOrderNo = new Element("orderno");
orderNo = String.valueOf( java.lang.System.currentTimeMillis() );
elemOrderNo.addContent( orderNo );
root.addContent(elemOrderNo);

//System.out.println("add elements to root");
for (int i=0; i<getCartSize(); i++) {  

item = (Item)getItem(i);
System.out.println("add one item: "+item.getItemname());

// save to XML file
addToXML(item);

// modify customorderitem table
modifyOrderItem(item);
}

//..... modify customorder table
modifyOrder(name, address);

//System.out.println("add ok!");
try {
close();
}
catch (JDOMException e) {
System.out.println(e.toString());
}
catch (IOException e) {
System.out.println(e.toString());
}
}
}  

classpath设置如下：

.;c:\jdk1.5.0\lib;c:\jdk1.5.0\lib\tools.jar;c:\jdk1.5.0\lib\dt.jar;
c:\jdk1.5.0\jre\lib\dt.jar;C:\dev\sax2\sax2.jar;
C:\jdom-b9\build\jdom.jar;
C:\dev\soap-2_3_1\lib\soap.jar;C:\dev\xerces-1_2_0\xerces.jar;
C:\dev\xerces-1_2_0\xercesSamples.jar;C:\Tomcat 5.0\common\lib\servlet-api.jar;
C:\Tomcat 5.0\bin;C:\dev\xt\sax.jar;C:\dev\xt\xt.jar;
C:\dev\jaxp parser\Jaxp1.0.1\parser.jar