package chap6;
import com.oreilly.javaxslt.util.StylesheetCache;
import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;
/**
* A modification of PersonalDataServlet that uses the
* com.oreilly.javaxslt.util.StylesheetCache class.
*/
public class PersonalDataCachedServlet extends HttpServlet {
private PersonalDataXML personalDataXML = new PersonalDataXML();
private String editXSLTFileName;
private String thanksXSLTFileName;
/**
* One-time initialization of this Servlet.
*/
public void init() throws UnavailableException {
this.editXSLTFileName = getServletContext().getRealPath(
"/WEB-INF/xslt/editPersonalData.xslt");
this.thanksXSLTFileName = getServletContext().getRealPath(
"/WEB-INF/xslt/confirmPersonalData.xslt");
}
/**
* Handles HTTP GET requests, such as when the user types in
* a URL into his or her browser or clicks on a hyperlink.
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws IOException,
ServletException {
PersonalData personalData = getPersonalData(request);
// the third parameter, 'false', indicates that error
// messages should not be displayed when showing the page.
showPage(response, personalData, false, this.editXSLTFileName);
}
/**
* Handles HTTP POST requests, such as when the user clicks on
* a Submit button to update his or her personal data.
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws IOException,
ServletException {
// locate the personal data object and update it with
// the information the user just submitted.
PersonalData pd = getPersonalData(request);
pd.setFirstName(request.getParameter("firstName"));
pd.setLastName(request.getParameter("lastName"));
pd.setDaytimePhone(request.getParameter("daytimePhone"));
pd.setEveningPhone(request.getParameter("eveningPhone"));
pd.setEmail(request.getParameter("email"));
if (!pd.isValid()) {
// show the 'Edit' page with an error message
showPage(response, pd, true, this.editXSLTFileName);
} else {
// show a confirmation page
showPage(response, pd, false, this.thanksXSLTFileName);
}
}
/**
* A helper method that sends the personal data to the client
* browser as HTML. It does this by applying an XSLT stylesheet
* to the DOM tree.
*/
private void showPage(HttpServletResponse response,
PersonalData personalData, boolean includeErrors,
String xsltFileName) throws IOException, ServletException {
try {
org.w3c.dom.Document domDoc =
this.personalDataXML.produceDOMDocument(
personalData, includeErrors);
Transformer trans =
StylesheetCache.newTransformer(xsltFileName);
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
trans.transform(new DOMSource(domDoc), new StreamResult(writer));
} catch (Exception ex) {
showErrorPage(response, ex);
}
}
/**
* If any exceptions occur, this method can be called to display
* the stack trace in the browser window.
*/
private void showErrorPage(HttpServletResponse response,
Throwable throwable) throws IOException {
PrintWriter pw = response.getWriter();
pw.println("<html><body><h1>An Error Has Occurred</h1><pre>");
throwable.printStackTrace(pw);
pw.println("</pre></body></html>");
}
/**
* A helper method that retrieves the PersonalData object from
* the HttpSession.
*/
private PersonalData getPersonalData(HttpServletRequest request) {
HttpSession session = request.getSession(true);
PersonalData pd = (PersonalData) session.getAttribute(
"chap6.PersonalData");
if (pd == null) {
pd = new PersonalData();
session.setAttribute("chap6.PersonalData", pd);
}
return pd;
}
}
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