/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jakarta.servlet;
import java.io.IOException;
/**
* 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 <code>RequestDispatcher</code> object, which is
* used as a wrapper around a server resource located at a particular path or given by a particular name.
* <p>
* This interface is intended to wrap servlets, but a servlet container can create <code>RequestDispatcher</code>
* objects to wrap any type of resource.
*
* @see ServletContext#getRequestDispatcher(String)
* @see ServletContext#getNamedDispatcher(String)
* @see ServletRequest#getRequestDispatcher(String)
*/
public interface RequestDispatcher {
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_REQUEST_URI = "jakarta.servlet.forward.request_uri";
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_CONTEXT_PATH = "jakarta.servlet.forward.context_path";
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_MAPPING = "jakarta.servlet.forward.mapping";
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_PATH_INFO = "jakarta.servlet.forward.path_info";
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_SERVLET_PATH = "jakarta.servlet.forward.servlet_path";
/**
* The name of the request attribute that should be set by the container when the
* {@link #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
*/
String FORWARD_QUERY_STRING = "jakarta.servlet.forward.query_string";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 3.0
*/
String INCLUDE_REQUEST_URI = "jakarta.servlet.include.request_uri";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 3.0
*/
String INCLUDE_CONTEXT_PATH = "jakarta.servlet.include.context_path";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 3.0
*/
String INCLUDE_PATH_INFO = "jakarta.servlet.include.path_info";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 4.0
*/
String INCLUDE_MAPPING = "jakarta.servlet.include.mapping";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 3.0
*/
String INCLUDE_SERVLET_PATH = "jakarta.servlet.include.servlet_path";
/**
* The name of the request attribute that should be set by the container when the
* {@link #include(ServletRequest, ServletResponse)} method is called on the {@code RequestDispatcher} obtained by a
* path and not by a name. It provides information on the path that was used to obtain the {@code RequestDispatcher}
* instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for
* details.
*
* @since Servlet 3.0
*/
String INCLUDE_QUERY_STRING = "jakarta.servlet.include.query_string";
/**
* 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 {@code java.lang.Throwable}. See the chapter "Error
* Handling" in the Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_EXCEPTION = "jakarta.servlet.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 {@code java.lang.Class}. See the chapter "Error Handling"
* in the Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_EXCEPTION_TYPE = "jakarta.servlet.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 {@code String}. See the chapter "Error Handling" in the
* Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_MESSAGE = "jakarta.servlet.error.message";
/**
* The name of the request attribute under which the method of the request whose processing caused the error is
* propagated during an error dispatch.
*
* @since Servlet 6.1
*/
String ERROR_METHOD = "jakarta.servlet.error.method";
/**
* 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 {@code String}. See the chapter "Error Handling" in the
* Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_REQUEST_URI = "jakarta.servlet.error.request_uri";
/**
* The name of the request attribute under which the query string for request whose processing caused the error is
* propagated during an error dispatch
*
* @since Servlet 6.1
*/
String ERROR_QUERY_STRING = "jakarta.servlet.error.query_string";
/**
* 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 {@code String}. See the chapter "Error Handling" in the
* Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_SERVLET_NAME = "jakarta.servlet.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 {@code java.lang.Integer}. See the chapter "Error
* Handling" in the Servlet Specification for details.
*
* @since Servlet 3.0
*/
String ERROR_STATUS_CODE = "jakarta.servlet.error.status_code";
/**
* 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.
* <p>
* For a <code>RequestDispatcher</code> obtained via <code>getRequestDispatcher()</code>, the
* <code>ServletRequest</code> object has its path elements and parameters adjusted to match the path of the target
* resource.
* <p>
* <code>forward</code> 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
* <code>IllegalStateException</code>. Uncommitted output in the response buffer is automatically cleared before the
* forward.
* <p>
* 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 {@link ServletRequestWrapper} or {@link ServletResponseWrapper} classes
* that wrap them.
*
* @param request a {@link ServletRequest} object that represents the request the client makes of the servlet
* @param response a {@link ServletResponse} object that represents the response the servlet returns to the client
*
* @exception ServletException if the target resource throws this exception
* @exception IOException if the target resource throws this exception
* @exception IllegalStateException if the response was already committed
*/
void forward(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.
* <p>
* The {@link 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.
* <p>
* 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 {@link ServletRequestWrapper} or {@link ServletResponseWrapper} classes
* that wrap them.
*
* @param request a {@link ServletRequest} object that contains the client's request
* @param response a {@link ServletResponse} object that contains the servlet's response
*
* @exception ServletException if the included resource throws this exception
* @exception IOException if the included resource throws this exception
*/
void include(ServletRequest request, ServletResponse response) throws ServletException, IOException;
}