贼贼手录

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<commonSpecs.length; i++) { 
SearchSpec searchSpec = commonSpecs[i]; 
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, 
"<H2>" + message + "</H2>"); 
} 



public void doPost(HttpServletRequest request, 
HttpServletResponse response) 
throws ServletException, IOException { 
doGet(request, response); 
} 
}