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 java.io.OutputStream; 020import java.util.concurrent.Callable; 021import javax.servlet.ServletRequest; 022import javax.servlet.http.HttpServletResponse; 023 024import org.springframework.core.MethodParameter; 025import org.springframework.core.ResolvableType; 026import org.springframework.http.ResponseEntity; 027import org.springframework.http.server.ServerHttpResponse; 028import org.springframework.http.server.ServletServerHttpResponse; 029import org.springframework.util.Assert; 030import org.springframework.web.context.request.NativeWebRequest; 031import org.springframework.web.context.request.async.WebAsyncUtils; 032import org.springframework.web.filter.ShallowEtagHeaderFilter; 033import org.springframework.web.method.support.HandlerMethodReturnValueHandler; 034import org.springframework.web.method.support.ModelAndViewContainer; 035 036/** 037 * Supports return values of type 038 * {@link org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody} 039 * and also {@code ResponseEntity<StreamingResponseBody>}. 040 * 041 * @author Rossen Stoyanchev 042 * @since 4.2 043 */ 044public class StreamingResponseBodyReturnValueHandler implements HandlerMethodReturnValueHandler { 045 046 @Override 047 public boolean supportsReturnType(MethodParameter returnType) { 048 if (StreamingResponseBody.class.isAssignableFrom(returnType.getParameterType())) { 049 return true; 050 } 051 else if (ResponseEntity.class.isAssignableFrom(returnType.getParameterType())) { 052 Class<?> bodyType = ResolvableType.forMethodParameter(returnType).getGeneric(0).resolve(); 053 return (bodyType != null && StreamingResponseBody.class.isAssignableFrom(bodyType)); 054 } 055 return false; 056 } 057 058 @Override 059 public void handleReturnValue(Object returnValue, MethodParameter returnType, 060 ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { 061 062 if (returnValue == null) { 063 mavContainer.setRequestHandled(true); 064 return; 065 } 066 067 HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class); 068 ServerHttpResponse outputMessage = new ServletServerHttpResponse(response); 069 070 if (returnValue instanceof ResponseEntity) { 071 ResponseEntity<?> responseEntity = (ResponseEntity<?>) returnValue; 072 response.setStatus(responseEntity.getStatusCodeValue()); 073 outputMessage.getHeaders().putAll(responseEntity.getHeaders()); 074 returnValue = responseEntity.getBody(); 075 if (returnValue == null) { 076 mavContainer.setRequestHandled(true); 077 outputMessage.flush(); 078 return; 079 } 080 } 081 082 ServletRequest request = webRequest.getNativeRequest(ServletRequest.class); 083 ShallowEtagHeaderFilter.disableContentCaching(request); 084 085 Assert.isInstanceOf(StreamingResponseBody.class, returnValue, "StreamingResponseBody expected"); 086 StreamingResponseBody streamingBody = (StreamingResponseBody) returnValue; 087 088 Callable<Void> callable = new StreamingResponseBodyTask(outputMessage.getBody(), streamingBody); 089 WebAsyncUtils.getAsyncManager(webRequest).startCallableProcessing(callable, mavContainer); 090 } 091 092 093 private static class StreamingResponseBodyTask implements Callable<Void> { 094 095 private final OutputStream outputStream; 096 097 private final StreamingResponseBody streamingBody; 098 099 public StreamingResponseBodyTask(OutputStream outputStream, StreamingResponseBody streamingBody) { 100 this.outputStream = outputStream; 101 this.streamingBody = streamingBody; 102 } 103 104 @Override 105 public Void call() throws Exception { 106 this.streamingBody.writeTo(this.outputStream); 107 return null; 108 } 109 } 110 111}