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/*
* 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 <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.
*
* @author Various
*
*
* @see ServletContext#getRequestDispatcher(java.lang.String)
* @see ServletContext#getNamedDispatcher(java.lang.String)
* @see ServletRequest#getRequestDispatcher(java.lang.String)
*
*/
public interface RequestDispatcher {
/**
* 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
*
*/
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.
*
* <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
*
*
*/
public void include(ServletRequest request, ServletResponse response)
throws ServletException, IOException;
}
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