001/*
002 * Copyright 2012-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.boot.web.servlet.filter;
018
019import java.io.IOException;
020
021import javax.servlet.FilterChain;
022import javax.servlet.ServletException;
023import javax.servlet.http.HttpServletRequest;
024import javax.servlet.http.HttpServletResponse;
025
026import org.springframework.context.ApplicationContext;
027import org.springframework.web.filter.OncePerRequestFilter;
028
029/**
030 * {@link OncePerRequestFilter} to add an {@literal X-Application-Context} header that
031 * contains the {@link ApplicationContext#getId() ApplicationContext ID}.
032 *
033 * @author Phillip Webb
034 * @author Venil Noronha
035 * @since 2.0.0
036 */
037public class ApplicationContextHeaderFilter extends OncePerRequestFilter {
038
039        /**
040         * Public constant for {@literal X-Application-Context}.
041         */
042        public static final String HEADER_NAME = "X-Application-Context";
043
044        private final ApplicationContext applicationContext;
045
046        public ApplicationContextHeaderFilter(ApplicationContext context) {
047                this.applicationContext = context;
048        }
049
050        @Override
051        protected void doFilterInternal(HttpServletRequest request,
052                        HttpServletResponse response, FilterChain filterChain)
053                        throws ServletException, IOException {
054                response.addHeader(HEADER_NAME, this.applicationContext.getId());
055                filterChain.doFilter(request, response);
056        }
057
058}