javax.servlet
Interface RequestDispatcher
public interface RequestDispatcher
Defines an object that receives requests from the client
and sends them to any resource (such as a servlet,
HTML file, or JSP file) on the server. The servlet
container creates the
RequestDispatcher object,
which is used as a wrapper around a server resource located
at a particular path or given by a particular name.
This interface is intended to wrap servlets,
but a servlet container can create
RequestDispatcher
objects to wrap any type of resource.
ServletContext.getRequestDispatcher(java.lang.String), ServletContext.getNamedDispatcher(java.lang.String), ServletRequest.getRequestDispatcher(java.lang.String)
forward
public void forward(ServletRequest request,
ServletResponse response)
throws ServletException Forwards a request from
a servlet to another resource (servlet, JSP file, or
HTML file) on the server. This method allows
one servlet to do preliminary processing of
a request and another resource to generate
the response.
For a
RequestDispatcher obtained via
getRequestDispatcher(), the
ServletRequest
object has its path elements and parameters adjusted to match
the path of the target resource.
forward should be called before the response has been
committed to the client (before response body output has been flushed).
If the response already has been committed, this method throws
an
IllegalStateException.
Uncommitted output in the response buffer is automatically cleared
before the forward.
The request and response parameters must be either the same
objects as were passed to the calling servlet's service method or be
subclasses of the
ServletRequestWrapper or
ServletResponseWrapper classes
that wrap them.
request - a ServletRequest object
that represents the request the client
makes of the servletresponse - a ServletResponse object
that represents the response the servlet
returns to the client
ServletException - if the target resource throws this exception
include
public void include(ServletRequest request,
ServletResponse response)
throws ServletException
Includes the content of a resource (servlet, JSP page,
HTML file) in the response. In essence, this method enables
programmatic server-side includes.
The
ServletResponse object has its path elements
and parameters remain unchanged from the caller's. The included
servlet cannot change the response status code or set headers;
any attempt to make a change is ignored.
The request and response parameters must be either the same
objects as were passed to the calling servlet's service method or be
subclasses of the
ServletRequestWrapper or
ServletResponseWrapper classes
that wrap them.
request - a ServletRequest object
that contains the client's requestresponse - a ServletResponse object
that contains the servlet's response
ServletException - if the included resource throws this exception