|  | /* | 
|  | * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved. | 
|  | * | 
|  | * This program and the accompanying materials are made available under the | 
|  | * terms of the Eclipse Public License v. 2.0, which is available at | 
|  | * http://www.eclipse.org/legal/epl-2.0. | 
|  | * | 
|  | * This Source Code may also be made available under the following Secondary | 
|  | * Licenses when the conditions for such availability set forth in the | 
|  | * Eclipse Public License v. 2.0 are satisfied: GNU General Public License, | 
|  | * version 2 with the GNU Classpath Exception, which is available at | 
|  | * https://www.gnu.org/software/classpath/license.html. | 
|  | * | 
|  | * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 | 
|  | */ | 
|  |  | 
|  | import java.io.IOException; | 
|  | import java.io.PrintWriter; | 
|  |  | 
|  | import javax.servlet.ServletException; | 
|  | import javax.servlet.http.HttpServlet; | 
|  | import javax.servlet.http.HttpServletRequest; | 
|  | import javax.servlet.http.HttpServletResponse; | 
|  |  | 
|  | public class SetHeadersServlet extends HttpServlet { | 
|  |  | 
|  | public void doGet(HttpServletRequest request, | 
|  | HttpServletResponse response) | 
|  | throws ServletException, IOException { | 
|  |  | 
|  | // The Cache-Control header often takes multiple values | 
|  | response.setHeader("Cache-Control","no-cache"); | 
|  |  | 
|  | // We have to use addHeader( ) to prevent setHeader( ) from replacing | 
|  | // the existing value. | 
|  | response.addHeader("Cache-Control","no-store"); | 
|  |  | 
|  | // We now have multiple values for the Cache-Control header. | 
|  | // If we try to replace the existing values with setHeader( ), only | 
|  | // one is replaced, contrary to the requirements of SRV.5.2 | 
|  | // (second paragraph) | 
|  | response.setHeader("Cache-Control","public"); | 
|  | } | 
|  |  | 
|  | } |