Basic Servlet Reference
January 8, 2010
This post lists the basic code required to implement a Java servlet.
Handling GET requests
Create a method with the following signature:
public void doGet(HttpServletRequest pRequest, HttpServletResponse pResponse) throws ServletException, IOException
Handling POST requests
Same as for GET, but with a different method name:
public void doPost(HttpServletRequest pRequest, HttpServletResponse pResponse) throws ServletException, IOException
Getting page parameters
This works for both GET and POST parameters:
String lNewPassword = pRequest.getParameter("newPassword");
Writing The Response
An example of returning a string full of HTML back to the browser/caller:
PrintWriter lWriter = pResponse.getWriter(); lWriter.append(lHtml); lWriter.close(); pResponse.setContentType("text/html");
Sending a 404 Response
Other error codes are available in SC_ contants.
pResponse.sendError(HttpServletResponse.SC_NOT_FOUND, "Token Invalid");
Sending A Redirect
Redirect to a different page client side
pResponse.sendRedirect("/path/to/go/to/");
Getting Path Requested
The path, hostname and port number are available through different methods on the HttpServletRequest instance
String lMachine = "http://" + pRequest.getLocalName() + ":" + pRequest.getLocalPort(); String lUri = pRequest.getRequestURI();
