Here's a simple example that reads parameters named
param1, param2, and param3, listing their values in a bulleted list. Note that, although you are required to specify response settings (content type, status line, other HTTP headings) before beginning to generate the content, there is no requirement that you read the request parameters at any particular time. Also note you can easily make servlets that can handle both
GET and POST data, simply by having its doPost method call doGet or by overriding service (which calls doGet, doPost, doHead, etc.). This is good standard practice, since it requires very little extra work and permits flexibility on the part of the client. If you're used to the traditional CGI approach where you read POST data via the standard input, you should note that there is a similar way with servlets by first calling getReader or getInputStream on the HttpServletRequest. This is a bad idea for regular parameters, but might be of use for uploaded files or POST data being sent by custom clients rather than via HTML forms. Note, however, that if you read the POST data in that manner, it might no longer be found by getParameter. ThreeParams.java
package hall;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class ThreeParams extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Reading Three Request Parameters";
out.println(ServletUtilities.headWithTitle(title) +
"<BODY>\n" +
"<H1 ALIGN=CENTER>" + title + "</H1>\n" +
"<UL>\n" +
" <LI>param1: "
+ request.getParameter("param1") + "\n" +
" <LI>param2: "
+ request.getParameter("param2") + "\n" +
" <LI>param3: "
+ request.getParameter("param3") + "\n" +
"</UL>\n" +
"</BODY></HTML>");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}Output
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