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8.6 A Customized Search Engine Interface

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Listing 8.5 CustomizedSearchEngines.java 

package coreservlets;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.net.*;

/** A variation of the SearchEngine servlet that uses

 *  cookies to remember users choices. These values

 *  are then used by the SearchEngineFrontEnd servlet

 *  to initialize the form based front end.

 */

public class CustomizedSearchEngines extends HttpServlet {

  public void doGet(HttpServletRequest request,

                    HttpServletResponse response)

      throws ServletException, IOException {

    String searchString = request.getParameter("searchString");

    if ((searchString == null) ||

        (searchString.length() == 0)) {

      reportProblem(response, "Missing search string.");

      return;

    }

    Cookie searchStringCookie =

      new LongLivedCookie("searchString", searchString);

    response.addCookie(searchStringCookie);

    // The URLEncoder changes spaces to "+" signs and other

    // non alphanumeric characters to "%XY", where XY is the

    // hex value of the ASCII (or ISO Latin 1) character.

    // Browsers always URL encode form values, so the

    // getParameter method decodes automatically. But since

    // we're just passing this on to another server, we need to

    // re encode it.

    searchString = URLEncoder.encode(searchString);

    String numResults = request.getParameter("numResults");

    if ((numResults == null) ||

        (numResults.equals("0")) ||

        (numResults.length() == 0)) {

      numResults = "10";

    }

    Cookie numResultsCookie =

      new LongLivedCookie("numResults", numResults);

    response.addCookie(numResultsCookie);

    String searchEngine = request.getParameter("searchEngine");

    if (searchEngine == null) {

      reportProblem(response, "Missing search engine name.");

      return;

    }

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