https://projects.eclipse.org/projects/ee4j.servlet: Provides, via submodules, a base configuration for JBoss project builds, as well as a derived configuration supporting multi-release JARs (JBoss by Red Hat)
  • Ed Burns
  • Shing Wai Chan 
/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates and others.
 * All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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
See Also:
/**
 * 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 {

    
The name of the request attribute under which the original request URI is made available to the target of a forward 
/**
     * The name of the request attribute under which the original request URI is made available to the target of a
     * {@link #forward(ServletRequest,ServletResponse) forward}
     */
    static final String FORWARD_REQUEST_URI = "javax.servlet.forward.request_uri";

    
The name of the request attribute under which the original context path is made available to the target of a forward 
/**
     * The name of the request attribute under which the original context path is made available to the target of a
     * {@link #forward(ServletRequest,ServletResponse) forward}
     */
    static final String FORWARD_CONTEXT_PATH = "javax.servlet.forward.context_path";

    
The name of the request attribute under which the original HttpServletMapping is made available to the target of a forward 
Since:4.0
/**
     * The name of the request attribute under which the original {@link javax.servlet.http.HttpServletMapping} is made
     * available to the target of a {@link #forward(ServletRequest,ServletResponse) forward}
     * 
     * @since 4.0
     */
    static final String FORWARD_MAPPING = "javax.servlet.forward.mapping";

    
The name of the request attribute under which the original path info is made available to the target of a forward 
/**
     * The name of the request attribute under which the original path info is made available to the target of a
     * {@link #forward(ServletRequest,ServletResponse) forward}
     */
    static final String FORWARD_PATH_INFO = "javax.servlet.forward.path_info";

    
The name of the request attribute under which the original servlet path is made available to the target of a forward 
/**
     * The name of the request attribute under which the original servlet path is made available to the target of a
     * {@link #forward(ServletRequest,ServletResponse) forward}
     */
    static final String FORWARD_SERVLET_PATH = "javax.servlet.forward.servlet_path";

    
The name of the request attribute under which the original query string is made available to the target of a forward 
/**
     * The name of the request attribute under which the original query string is made available to the target of a
     * {@link #forward(ServletRequest,ServletResponse) forward}
     */
    static final String FORWARD_QUERY_STRING = "javax.servlet.forward.query_string";

    
The name of the request attribute under which the request URI of the target of an include is stored 
/**
     * The name of the request attribute under which the request URI of the target of an
     * {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_REQUEST_URI = "javax.servlet.include.request_uri";

    
The name of the request attribute under which the context path of the target of an include is stored 
/**
     * The name of the request attribute under which the context path of the target of an
     * {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_CONTEXT_PATH = "javax.servlet.include.context_path";

    
The name of the request attribute under which the path info of the target of an include is stored 
/**
     * The name of the request attribute under which the path info of the target of an
     * {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_PATH_INFO = "javax.servlet.include.path_info";

    
The name of the request attribute under which the HttpServletMapping of the target of an include is stored 
/**
     * The name of the request attribute under which the {@link javax.servlet.http.HttpServletMapping} of the target of
     * an {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_MAPPING = "javax.servlet.include.mapping";

    
The name of the request attribute under which the servlet path of the target of an include is stored 
/**
     * The name of the request attribute under which the servlet path of the target of an
     * {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_SERVLET_PATH = "javax.servlet.include.servlet_path";

    
The name of the request attribute under which the query string of the target of an include is stored 
/**
     * The name of the request attribute under which the query string of the target of an
     * {@link #include(ServletRequest,ServletResponse) include} is stored
     */
    static final String INCLUDE_QUERY_STRING = "javax.servlet.include.query_string";

    
The name of the request attribute under which the exception object is propagated during an error dispatch

/**
     * The name of the request attribute under which the exception object is propagated during an error dispatch
     */
    public static final String ERROR_EXCEPTION = "javax.servlet.error.exception";

    
The name of the request attribute under which the type of the exception object is propagated during an error
dispatch

/**
     * The name of the request attribute under which the type of the exception object is propagated during an error
     * dispatch
     */
    public static final String ERROR_EXCEPTION_TYPE = "javax.servlet.error.exception_type";

    
The name of the request attribute under which the exception message is propagated during an error dispatch

/**
     * The name of the request attribute under which the exception message is propagated during an error dispatch
     */
    public static final String ERROR_MESSAGE = "javax.servlet.error.message";

    
The name of the request attribute under which the request URI whose processing caused the error is propagated
during an error dispatch

/**
     * The name of the request attribute under which the request URI whose processing caused the error is propagated
     * during an error dispatch
     */
    public static final String ERROR_REQUEST_URI = "javax.servlet.error.request_uri";

    
The name of the request attribute under which the name of the servlet in which the error occurred is propagated
during an error dispatch

/**
     * The name of the request attribute under which the name of the servlet in which the error occurred is propagated
     * during an error dispatch
     */
    public static final String ERROR_SERVLET_NAME = "javax.servlet.error.servlet_name";

    
The name of the request attribute under which the response status is propagated during an error dispatch

/**
     * The name of the request attribute under which the response status is propagated during an error dispatch
     */
    public static final String ERROR_STATUS_CODE = "javax.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.


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.

Params:
  • 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:
See Also:
/**
     * 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.
     *
     * <p>
     * This method sets the dispatcher type of the given request to <code>DispatcherType.FORWARD</code>.
     *
     * @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
     *
     * @throws ServletException      if the target resource throws this exception
     *
     * @throws IOException           if the target resource throws this exception
     *
     * @throws IllegalStateException if the response was already committed
     *
     * @see ServletRequest#getDispatcherType
     */
    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 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.

Params:
Throws:
See Also:
/**
     *
     * 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.
     *
     * <p>
     * This method sets the dispatcher type of the given request to <code>DispatcherType.INCLUDE</code>.
     *
     * @param request  a {@link ServletRequest} object that contains the client's request
     *
     * @param response a {@link ServletResponse} object that contains the servlet's response
     *
     * @throws ServletException if the included resource throws this exception
     *
     * @throws IOException      if the included resource throws this exception
     *
     * @see ServletRequest#getDispatcherType
     */
    public void include(ServletRequest request, ServletResponse response) throws ServletException, IOException;
}