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.

See Also:

  • Field Details

    • FORWARD_REQUEST_URI

      static final String FORWARD_REQUEST_URI
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • FORWARD_CONTEXT_PATH

      static final String FORWARD_CONTEXT_PATH
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • FORWARD_MAPPING

      static final String FORWARD_MAPPING
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 4.0
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    • FORWARD_PATH_INFO

      static final String FORWARD_PATH_INFO
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
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    • FORWARD_SERVLET_PATH

      static final String FORWARD_SERVLET_PATH
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • FORWARD_QUERY_STRING

      static final String FORWARD_QUERY_STRING
      The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • INCLUDE_REQUEST_URI

      static final String INCLUDE_REQUEST_URI
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • INCLUDE_CONTEXT_PATH

      static final String INCLUDE_CONTEXT_PATH
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • INCLUDE_PATH_INFO

      static final String INCLUDE_PATH_INFO
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • INCLUDE_MAPPING

      static final String INCLUDE_MAPPING
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 4.0
      See Also:

    • INCLUDE_SERVLET_PATH

      static final String INCLUDE_SERVLET_PATH
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • INCLUDE_QUERY_STRING

      static final String INCLUDE_QUERY_STRING
      The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_EXCEPTION

      static final String ERROR_EXCEPTION
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Throwable. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_EXCEPTION_TYPE

      static final String ERROR_EXCEPTION_TYPE
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Class. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_MESSAGE

      static final String ERROR_MESSAGE
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type String. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_REQUEST_URI

      static final String ERROR_REQUEST_URI
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type String. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_SERVLET_NAME

      static final String ERROR_SERVLET_NAME
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type String. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

    • ERROR_STATUS_CODE

      static final String ERROR_STATUS_CODE
      The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Integer. See the chapter "Error Handling" in the Servlet Specification for details.
      Since:
      Servlet 3.0
      See Also:

  • Method Details

    • 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 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.

      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
      IOException - if the target resource throws this exception
      IllegalStateException - if the response was already committed

    • 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 or ServletResponseWrapper classes that wrap them.

      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
      IOException - if the included resource throws this exception