Exchange POST data between servlets?

Question

Hello all
First of all, my apologies for my English. This is the first time writing to forum.
I�m new to java and I need a little help with servlets.
I have the servlets A, B and C.
Servlet A just display a page with a form tag witch send the data to Servlet C via POST method. What I want is to intercede the Servlet B between them and check the integrity of those POST data.
For example: Servlet A send data to Servlet B via POST method, Servlet B check the integrity of those data, and finally Servlet B send those data to Servlet C via POST method.
For now the only I have done is to send the data to B and transfer the data to C with GET method.
How can I send data with POST method in a servlet?
The code so far:
     String urlstr = new String();
     String str1 = request.getParameter("st_name");
String str2 = request.getParameter("st_birth");
String str3 = request.getParameter("st_class");
��some check ����
     urlstr = "/student/check_st?st_name=" + str1 + "&st_birth=" + str2 + "&st_class=" + str3;
     response.sendRedirect(urlstr);
Thanks in advanced.
Ilias

Answer 1

You should use the RequestDispatcher.forward(request,response) method.
For example, inside Servlet B do this:
public void doPost(ServletRequest request, ServletResponse response) {
    ... validate parameters ...
    RequestDispatcher dispatcher = request.getRequestDisplatcher("ServletC");
    dispatcher.forward(request,response);
}This prevents an extra request-response cycle to the client and between the .forward() and .include() methods of the RequestDispatcher, should be considered the preferred way of server-side redirection unless there is a specific need to go to the client first.
See the J2EE API:
http://java.sun.com/javaee/5/docs/api/