javax.servlet.RequestDispatcher Maven / Gradle / Ivy
/*
* 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 javax.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 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
* @version $Version$
*
* @see ServletContext#getRequestDispatcher(java.lang.String)
* @see ServletContext#getNamedDispatcher(java.lang.String)
* @see ServletRequest#getRequestDispatcher(java.lang.String)
*
*/
public interface RequestDispatcher {
public static final String ERROR_EXCEPTION = "javax.servlet.error.exception";
public static final String ERROR_EXCEPTION_TYPE = "javax.servlet.error.exception_type";
public static final String ERROR_MESSAGE = "javax.servlet.error.message";
public static final String ERROR_REQUEST_URI = "javax.servlet.error.request_uri";
public static final String ERROR_SERVLET_NAME = "javax.servlet.error.servlet_name";
public static final String ERROR_STATUS_CODE = "javax.servlet.error.status_code";
public static final String FORWARD_CONTEXT_PATH = "javax.servlet.forward.context_path";
public static final String FORWARD_PATH_INFO = "javax.servlet.forward.path_info";
public static final String FORWARD_QUERY_STRING = "javax.servlet.forward.query_string";
public static final String FORWARD_REQUEST_URI = "javax.servlet.forward.request_uri";
public static final String FORWARD_SERVLET_PATH = "javax.servlet.forward.servlet_path";
public static final String INCLUDE_CONTEXT_PATH = "javax.servlet.include.context_path";
public static final String INCLUDE_PATH_INFO = "javax.servlet.include.path_info";
public static final String INCLUDE_QUERY_STRING = "javax.servlet.include.query_string";
public static final String INCLUDE_REQUEST_URI = "javax.servlet.include.request_uri";
public static final String INCLUDE_SERVLET_PATH = "javax.servlet.include.servlet_path";
/**
* 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 {@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
*/
public 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.
*
*
* 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.
*
*
* 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
*/
public void include(ServletRequest request, ServletResponse response)
throws ServletException, IOException;
}