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}