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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 theRequestDispatcher
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.
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Field Summary
Fields Modifier and Type Field and Description static String
ERROR_EXCEPTION
The name of the request attribute under which the exception object is propagated during an error dispatchstatic String
ERROR_EXCEPTION_TYPE
The name of the request attribute under which the type of the exception object is propagated during an error dispatchstatic String
ERROR_MESSAGE
The name of the request attribute under which the exception message is propagated during an error dispatchstatic String
ERROR_REQUEST_URI
The name of the request attribute under which the request URI whose processing caused the error is propagated during an error dispatchstatic String
ERROR_SERVLET_NAME
The name of the request attribute under which the name of the servlet in which the error occurred is propagated during an error dispatchstatic String
ERROR_STATUS_CODE
The name of the request attribute under which the response status is propagated during an error dispatchstatic String
FORWARD_CONTEXT_PATH
The name of the request attribute under which the original context path is made available to the target of aforward
static String
FORWARD_PATH_INFO
The name of the request attribute under which the original path info is made available to the target of aforward
static String
FORWARD_QUERY_STRING
The name of the request attribute under which the original query string is made available to the target of aforward
static String
FORWARD_REQUEST_URI
The name of the request attribute under which the original request URI is made available to the target of aforward
static String
FORWARD_SERVLET_PATH
The name of the request attribute under which the original servlet path is made available to the target of aforward
static String
INCLUDE_CONTEXT_PATH
The name of the request attribute under which the context path of the target of aninclude
is storedstatic String
INCLUDE_PATH_INFO
The name of the request attribute under which the path info of the target of aninclude
is storedstatic String
INCLUDE_QUERY_STRING
The name of the request attribute under which the query string of the target of aninclude
is storedstatic String
INCLUDE_REQUEST_URI
The name of the request attribute under which the request URI of the target of aninclude
is storedstatic String
INCLUDE_SERVLET_PATH
The name of the request attribute under which the servlet path of the target of aninclude
is stored
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Method Summary
All Methods Instance Methods Abstract Methods 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.
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Field Detail
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FORWARD_REQUEST_URI
static final String FORWARD_REQUEST_URI
The name of the request attribute under which the original request URI is made available to the target of aforward
- See Also:
- Constant Field Values
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FORWARD_CONTEXT_PATH
static final String FORWARD_CONTEXT_PATH
The name of the request attribute under which the original context path is made available to the target of aforward
- See Also:
- Constant Field Values
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FORWARD_PATH_INFO
static final String FORWARD_PATH_INFO
The name of the request attribute under which the original path info is made available to the target of aforward
- See Also:
- Constant Field Values
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FORWARD_SERVLET_PATH
static final String FORWARD_SERVLET_PATH
The name of the request attribute under which the original servlet path is made available to the target of aforward
- See Also:
- Constant Field Values
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FORWARD_QUERY_STRING
static final String FORWARD_QUERY_STRING
The name of the request attribute under which the original query string is made available to the target of aforward
- See Also:
- Constant Field Values
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INCLUDE_REQUEST_URI
static final String INCLUDE_REQUEST_URI
The name of the request attribute under which the request URI of the target of aninclude
is stored- See Also:
- Constant Field Values
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INCLUDE_CONTEXT_PATH
static final String INCLUDE_CONTEXT_PATH
The name of the request attribute under which the context path of the target of aninclude
is stored- See Also:
- Constant Field Values
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INCLUDE_PATH_INFO
static final String INCLUDE_PATH_INFO
The name of the request attribute under which the path info of the target of aninclude
is stored- See Also:
- Constant Field Values
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INCLUDE_SERVLET_PATH
static final String INCLUDE_SERVLET_PATH
The name of the request attribute under which the servlet path of the target of aninclude
is stored- See Also:
- Constant Field Values
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INCLUDE_QUERY_STRING
static final String INCLUDE_QUERY_STRING
The name of the request attribute under which the query string of the target of aninclude
is stored- See Also:
- Constant Field Values
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ERROR_EXCEPTION
static final String ERROR_EXCEPTION
The name of the request attribute under which the exception object is propagated during an error dispatch- See Also:
- Constant Field Values
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ERROR_EXCEPTION_TYPE
static final String ERROR_EXCEPTION_TYPE
The name of the request attribute under which the type of the exception object is propagated during an error dispatch- See Also:
- Constant Field Values
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ERROR_MESSAGE
static final String ERROR_MESSAGE
The name of the request attribute under which the exception message is propagated during an error dispatch- See Also:
- Constant Field Values
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ERROR_REQUEST_URI
static final String ERROR_REQUEST_URI
The name of the request attribute under which the request URI whose processing caused the error is propagated during an error dispatch- See Also:
- Constant Field Values
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ERROR_SERVLET_NAME
static final String ERROR_SERVLET_NAME
The name of the request attribute under which the name of the servlet in which the error occurred is propagated during an error dispatch- See Also:
- Constant Field Values
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ERROR_STATUS_CODE
static final String ERROR_STATUS_CODE
The name of the request attribute under which the response status is propagated during an error dispatch- See Also:
- Constant Field Values
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Method Detail
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forward
void forward(ServletRequest request, ServletResponse response) throws ServletException, 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.This method sets the dispatcher type of the given request to
DispatcherType.FORWARD
.- 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 exceptionIOException
- if the target resource throws this exceptionIllegalStateException
- if the response was already committed- See Also:
ServletRequest.getDispatcherType()
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include
void include(ServletRequest request, ServletResponse response) throws ServletException, 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.This method sets the dispatcher type of the given request to
DispatcherType.INCLUDE
.- 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 exceptionIOException
- if the included resource throws this exception- See Also:
ServletRequest.getDispatcherType()
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Vielen Dank im Voraus.
Dokument erstellt 11/06/2005, zuletzt geändert 18/08/2025
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-javaee-rf-javax/servlet/RequestDispatcher.html
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