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.

Author:: Various
See Also:: ServletContext.getRequestDispatcher(java.lang.String), ServletContext.getNamedDispatcher(java.lang.String), ServletRequest.getRequestDispatcher(java.lang.String)

Field Summary

Fields
Modifier and Type	Field	Description
`static java.lang.String`	`ERROR_EXCEPTION`	The name of the request attribute under which the exception object is propagated during an error dispatch
`static java.lang.String`	`ERROR_EXCEPTION_TYPE`	The name of the request attribute under which the type of the exception object is propagated during an error dispatch
`static java.lang.String`	`ERROR_MESSAGE`	The name of the request attribute under which the exception message is propagated during an error dispatch
`static java.lang.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
`static java.lang.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
`static java.lang.String`	`ERROR_STATUS_CODE`	The name of the request attribute under which the response status is propagated during an error dispatch
`static java.lang.String`	`FORWARD_CONTEXT_PATH`	The name of the request attribute under which the original context path is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_MAPPING`	The name of the request attribute under which the original `HttpServletMapping` is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_PATH_INFO`	The name of the request attribute under which the original path info is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_QUERY_STRING`	The name of the request attribute under which the original query string is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_REQUEST_URI`	The name of the request attribute under which the original request URI is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_SERVLET_PATH`	The name of the request attribute under which the original servlet path is made available to the target of a `forward`
`static java.lang.String`	`INCLUDE_CONTEXT_PATH`	The name of the request attribute under which the context path of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_MAPPING`	The name of the request attribute under which the `HttpServletMapping` of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_PATH_INFO`	The name of the request attribute under which the path info of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_QUERY_STRING`	The name of the request attribute under which the query string of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_REQUEST_URI`	The name of the request attribute under which the request URI of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_SERVLET_PATH`	The name of the request attribute under which the servlet path of the target of an `include` is stored

Method Summary

Modifier and Type	Method	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.

Field Details
- FORWARD_REQUEST_URI
  
  static final java.lang.String FORWARD_REQUEST_URI
  
  The name of the request attribute under which the original request URI is made available to the target of a forward
  
  See Also:
  
  Constant Field Values
- FORWARD_CONTEXT_PATH
  
  static final java.lang.String FORWARD_CONTEXT_PATH
  
  The name of the request attribute under which the original context path is made available to the target of a forward
  
  See Also:
  
  Constant Field Values
- FORWARD_MAPPING
  
  static final java.lang.String FORWARD_MAPPING
  
  The name of the request attribute under which the original HttpServletMapping is made available to the target of a forward
  
  Since:
  
  4.0
  
  See Also:
  
  Constant Field Values
- FORWARD_PATH_INFO
  
  static final java.lang.String FORWARD_PATH_INFO
  
  The name of the request attribute under which the original path info is made available to the target of a forward
  
  See Also:
  
  Constant Field Values
- FORWARD_SERVLET_PATH
  
  static final java.lang.String FORWARD_SERVLET_PATH
  
  The name of the request attribute under which the original servlet path is made available to the target of a forward
  
  See Also:
  
  Constant Field Values
- FORWARD_QUERY_STRING
  
  static final java.lang.String FORWARD_QUERY_STRING
  
  The name of the request attribute under which the original query string is made available to the target of a forward
  
  See Also:
  
  Constant Field Values
- INCLUDE_REQUEST_URI
  
  static final java.lang.String INCLUDE_REQUEST_URI
  
  The name of the request attribute under which the request URI of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- INCLUDE_CONTEXT_PATH
  
  static final java.lang.String INCLUDE_CONTEXT_PATH
  
  The name of the request attribute under which the context path of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- INCLUDE_PATH_INFO
  
  static final java.lang.String INCLUDE_PATH_INFO
  
  The name of the request attribute under which the path info of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- INCLUDE_MAPPING
  
  static final java.lang.String INCLUDE_MAPPING
  
  The name of the request attribute under which the HttpServletMapping of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- INCLUDE_SERVLET_PATH
  
  static final java.lang.String INCLUDE_SERVLET_PATH
  
  The name of the request attribute under which the servlet path of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- INCLUDE_QUERY_STRING
  
  static final java.lang.String INCLUDE_QUERY_STRING
  
  The name of the request attribute under which the query string of the target of an include is stored
  
  See Also:
  
  Constant Field Values
- ERROR_EXCEPTION
  
  static final java.lang.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
- ERROR_EXCEPTION_TYPE
  
  static final java.lang.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
- ERROR_MESSAGE
  
  static final java.lang.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
- ERROR_REQUEST_URI
  
  static final java.lang.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
- ERROR_SERVLET_NAME
  
  static final java.lang.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
- ERROR_STATUS_CODE
  
  static final java.lang.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
Method Details
- forward
  
  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 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.
  This method sets the dispatcher type of the given request to DispatcherType.FORWARD.
  
  Parameters:
  
  request - a ServletRequest object that represents the request the client makes of the servlet
  
  response - a ServletResponse 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
  
  java.lang.IllegalStateException - if the response was already committed
  
  See Also:
  
  ServletRequest.getDispatcherType()
- include
  
  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 or ServletResponseWrapper classes that wrap them.
  This method sets the dispatcher type of the given request to DispatcherType.INCLUDE.
  
  Parameters:
  
  request - a ServletRequest object that contains the client's request
  
  response - a ServletResponse 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
  
  See Also:
  
  ServletRequest.getDispatcherType()

Interface RequestDispatcher

Field Summary

Method Summary

Field Details

FORWARD_REQUEST_URI

FORWARD_CONTEXT_PATH

FORWARD_MAPPING

FORWARD_PATH_INFO

FORWARD_SERVLET_PATH

FORWARD_QUERY_STRING

INCLUDE_REQUEST_URI

INCLUDE_CONTEXT_PATH

INCLUDE_PATH_INFO

INCLUDE_MAPPING

INCLUDE_SERVLET_PATH

INCLUDE_QUERY_STRING

ERROR_EXCEPTION

ERROR_EXCEPTION_TYPE

ERROR_MESSAGE

ERROR_REQUEST_URI

ERROR_SERVLET_NAME

ERROR_STATUS_CODE

Method Details

forward

include