001/* 002 * Copyright 2002-2017 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 * https://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.web.servlet.mvc.method.annotation; 018 019import javax.servlet.http.HttpServletResponse; 020 021import org.springframework.core.MethodParameter; 022import org.springframework.http.HttpHeaders; 023import org.springframework.http.server.ServletServerHttpResponse; 024import org.springframework.lang.Nullable; 025import org.springframework.util.Assert; 026import org.springframework.web.context.request.NativeWebRequest; 027import org.springframework.web.method.support.HandlerMethodReturnValueHandler; 028import org.springframework.web.method.support.ModelAndViewContainer; 029 030/** 031 * Handles {@link HttpHeaders} return values. 032 * 033 * @author Stephane Nicoll 034 * @since 4.0.1 035 */ 036public class HttpHeadersReturnValueHandler implements HandlerMethodReturnValueHandler { 037 038 @Override 039 public boolean supportsReturnType(MethodParameter returnType) { 040 return HttpHeaders.class.isAssignableFrom(returnType.getParameterType()); 041 } 042 043 @Override 044 @SuppressWarnings("resource") 045 public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType, 046 ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { 047 048 mavContainer.setRequestHandled(true); 049 050 Assert.state(returnValue instanceof HttpHeaders, "HttpHeaders expected"); 051 HttpHeaders headers = (HttpHeaders) returnValue; 052 053 if (!headers.isEmpty()) { 054 HttpServletResponse servletResponse = webRequest.getNativeResponse(HttpServletResponse.class); 055 Assert.state(servletResponse != null, "No HttpServletResponse"); 056 ServletServerHttpResponse outputMessage = new ServletServerHttpResponse(servletResponse); 057 outputMessage.getHeaders().putAll(headers); 058 outputMessage.getBody(); // flush headers 059 } 060 } 061 062}