public interface RequestDispatcher
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)
Modifier and Type | Field and Description |
---|---|
static String |
ERROR_EXCEPTION |
static String |
ERROR_EXCEPTION_TYPE |
static String |
ERROR_MESSAGE |
static String |
ERROR_REQUEST_URI |
static String |
ERROR_SERVLET_NAME |
static String |
ERROR_STATUS_CODE |
static String |
FORWARD_CONTEXT_PATH |
static String |
FORWARD_PATH_INFO |
static String |
FORWARD_QUERY_STRING |
static String |
FORWARD_REQUEST_URI |
static String |
FORWARD_SERVLET_PATH |
static String |
INCLUDE_CONTEXT_PATH |
static String |
INCLUDE_PATH_INFO |
static String |
INCLUDE_QUERY_STRING |
static String |
INCLUDE_REQUEST_URI |
static String |
INCLUDE_SERVLET_PATH |
Modifier and Type | Method and Description |
---|---|
void |
forward(ServletRequest request,
ServletResponse response)
Forwards a request from
a servlet to another resource (servlet, JSP file, or
HTML file) on the server.
|
void |
include(ServletRequest request,
ServletResponse response)
Includes the content of a resource (servlet, JSP page,
HTML file) in the response.
|
static final String ERROR_EXCEPTION
static final String ERROR_EXCEPTION_TYPE
static final String ERROR_MESSAGE
static final String ERROR_REQUEST_URI
static final String ERROR_SERVLET_NAME
static final String ERROR_STATUS_CODE
static final String FORWARD_CONTEXT_PATH
static final String FORWARD_PATH_INFO
static final String FORWARD_QUERY_STRING
static final String FORWARD_REQUEST_URI
static final String FORWARD_SERVLET_PATH
static final String INCLUDE_CONTEXT_PATH
static final String INCLUDE_PATH_INFO
static final String INCLUDE_QUERY_STRING
static final String INCLUDE_REQUEST_URI
static final String INCLUDE_SERVLET_PATH
void forward(ServletRequest request, ServletResponse response) throws ServletException, IOException
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 clientServletException
- if the target resource throws this exceptionIOException
- if the target resource throws this exceptionIllegalStateException
- if the response was already committedvoid include(ServletRequest request, ServletResponse response) throws ServletException, IOException
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 responseServletException
- if the included resource throws this exceptionIOException
- if the included resource throws this exceptionCopyright © 2013. All rights reserved.