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javax.servlet Interface RequestDispatcher
- public abstract 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.
- See Also:
ServletContext.getRequestDispatcher(java.lang.String)
,ServletContext.getNamedDispatcher(java.lang.String)
,ServletRequest.getRequestDispatcher(java.lang.String)
Method Summary | |
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. |
Method Detail |
forward
public void forward(ServletRequest request, ServletResponse response) throws ServletException, java.io.IOException
- 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 viagetRequestDispatcher()
, theServletRequest
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 anIllegalStateException
. 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
orServletResponseWrapper
classes that wrap them. - Parameters:
request
- aServletRequest
object that represents the request the client makes of the servletresponse
- aServletResponse
object that represents the response the servlet returns to the client- Throws:
- ServletException - if the target resource throws this exception
- java.io.IOException - if the target resource throws this exception
- IllegalStateException - if the response was already committed
include
public void include(ServletRequest request, ServletResponse response) throws ServletException, java.io.IOException
- 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
orServletResponseWrapper
classes that wrap them. - Parameters:
request
- aServletRequest
object that contains the client's requestresponse
- aServletResponse
object that contains the servlet's response- Throws:
- ServletException - if the included resource throws this exception
- java.io.IOException - if the included resource throws this exception
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