XML by Example

The Data Tier

Listing 12.16 shows the data tier for Emailaholic. This data tier can gener-

ate a list of products in response to GET requests. It also accepts orders sent

with POST requests. For security purposes, the database username and

password must be provided.

Listing 12.16: XMLServer.java

package com.psol.xcommerce;

import java.io.*;

import java.sql.*;

import java.text.*;

import org.w3c.dom.*;

import javax.servlet.*;

import javax.servlet.http.*;

/**

* XMLServer returns database records in XML.

*

* @version Dec 23, 1999

* @author Benoît Marchal <[e-mail]>

*/

public class XMLServer

extends HttpServlet

{

/**

* currency formater for numbers

*/

protected NumberFormat formatter =

NumberFormat.getCurrencyInstance();

/**

* process GET request

* @param request HTTP request

* @param response hold the response

* @exception ServletException error processing the request

* @exception IOException error writing the result

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The Data Tier

EXAMPLE

continues

*/

protected void doGet(HttpServletRequest request,

HttpServletResponse response)

throws ServletException, IOException

{

response.setContentType(“application/xml”);

Writer writer = response.getWriter();

String sqlDriver = getInitParameter(“sql.driver”),

sqlURL = getInitParameter(“sql.url”),

sqlUser = getInitParameter(“sql.user”),

sqlPassword = getInitParameter(“sql.password”),

merchant = getInitParameter(“merchant”);

writer.write(“<?xml version=\”1.0\”?>”);

writer.write(“<products merchant=\””);

writer.write(merchant);

writer.write(“\”>”);

try

{

Class.forName(sqlDriver);

Connection connection =

DriverManager.getConnection(sqlURL,

sqlUser,

sqlPassword);

try

{

Statement stmt = connection.createStatement();

try

{

ResultSet rs =

stmt.executeQuery(“select id, name, “ +

“manufacturer, img, warranty, “ +

“description, price from products”);

while(rs.next())

{

writer.write(“<product id=\””);

writer.write(String.valueOf(rs.getInt(1)));

writer.write(“\” xmlns:em=\”http://www.emailaholic”);

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Chapter 12: Putting It All Together: An e-Commerce Example

Listing 12.16: continued

writer.write(“.com/xt/1.0\”><name>”);

writer.write(rs.getString(2));

writer.write(“</name><em:manufacturer>”);

writer.write(rs.getString(3));

writer.write(“</em:manufacturer><em:image>”);

writer.write(rs.getString(4));

writer.write(“</em:image><em:warranty>”);

writer.write(rs.getString(5));

writer.write(“</em:warranty><description>”);

writer.write(rs.getString(6));

writer.write(“</description><price>”);

writer.write(formatter.format(rs.getDouble(7)));

writer.write(“</price></product>”);

}

}

finally

{

stmt.close();

}

}

finally

{

connection.close();

}

}

catch(ClassNotFoundException e)

{

throw new ServletException(e);

}

catch(SQLException e)

{

throw new ServletException(e);

}

writer.write(“</products>”);

writer.flush();

}

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The Data Tier

continues

/**

* process POST request

* @param request HTTP request

* @param response hold the response

* @exception ServletException error processing the request

* @exception IOException error writing the result

*/

protected void doPost(HttpServletRequest request,

HttpServletResponse response)

throws ServletException, IOException

{

// there is no error checking at all

// if incorrect, throws an exception:

// it goes to a computer so it’s for technicians anyway

String sqlDriver = getInitParameter(“sql.driver”),

sqlURL = getInitParameter(“sql.url”),

sqlUser = request.getParameter(“user”),

sqlPassword = request.getParameter(“password”),

xmlData = request.getParameter(“xmldata”);

Reader reader = new StringReader(xmlData);

Document orderDocument = XMLUtil.parse(reader);

Element orderElement = orderDocument.getDocumentElement(),

buyerElement =

XMLUtil.extractFirst(orderElement,”buyer”),

productElement =

XMLUtil.extractFirst(orderElement,”product”);

String name = buyerElement.getAttribute(“name”),

street = buyerElement.getAttribute(“street”),

region = buyerElement.getAttribute(“region”),

postal_code =

buyerElement.getAttribute(“postal-code”),

locality = buyerElement.getAttribute(“locality”),

country = buyerElement.getAttribute(“country”),

email = buyerElement.getAttribute(“email”),

productid = productElement.getAttribute(“id”),

productname = productElement.getAttribute(“name”),

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Chapter 12: Putting It All Together: An e-Commerce Example

Listing 12.16: continued

productprice = productElement.getAttribute(“price”),

productquantity =

productElement.getAttribute(“quantity”);

try

{

Class.forName(sqlDriver);

Connection connection =

DriverManager.getConnection(sqlURL,

sqlUser,

sqlPassword);

try

{

PreparedStatement stmt =

connection.prepareStatement(

“insert into orders (name,street,region,” +

“postal_code,locality,country,email,” +

“productid,productname,productprice,” +

“productquantity) “ +

“values(?,?,?,?,?,?,?,?,?,?,?)”);

try

{

stmt.setString(1,name);

stmt.setString(2,street);

stmt.setString(3,region);

stmt.setString(4,postal_code);

stmt.setString(5,locality);

stmt.setString(6,country);

stmt.setString(7,email);

stmt.setString(8,productid);

stmt.setString(9,productname);

stmt.setDouble(10,

formatter.parse(productprice).doubleValue());

stmt.setString(11,productquantity);

stmt.executeUpdate();

connection.commit();

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The Data Tier

continues