package coreservlets;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import java.net.*;public class SearchEngines 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;}// 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";}String searchEngine =request.getParameter("searchEngine");if (searchEngine == null) {reportProblem(response, "Missing search engine name.");return;}SearchSpec[] commonSpecs = SearchSpec.getCommonSpecs();for(int i=0; i SearchSpec searchSpec = commonSpecs;if (searchSpec.getName().equals(searchEngine)) {String url =searchSpec.makeURL(searchString, numResults);response.sendRedirect(url);return;}}reportProblem(response, "Unrecognized search engine.");}private void reportProblem(HttpServletResponse response,String message)throws IOException {response.sendError(response.SC_NOT_FOUND,"" + message + "");