001/* 002 * Copyright 2002-2019 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; 021 022import javax.servlet.ServletRequest; 023import javax.servlet.http.HttpServletResponse; 024 025import org.springframework.core.MethodParameter; 026import org.springframework.core.ResolvableType; 027import org.springframework.http.ResponseEntity; 028import org.springframework.http.server.ServerHttpResponse; 029import org.springframework.http.server.ServletServerHttpResponse; 030import org.springframework.lang.Nullable; 031import org.springframework.util.Assert; 032import org.springframework.web.context.request.NativeWebRequest; 033import org.springframework.web.context.request.async.WebAsyncUtils; 034import org.springframework.web.filter.ShallowEtagHeaderFilter; 035import org.springframework.web.method.support.HandlerMethodReturnValueHandler; 036import org.springframework.web.method.support.ModelAndViewContainer; 037 038/** 039 * Supports return values of type 040 * {@link org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody} 041 * and also {@code ResponseEntity<StreamingResponseBody>}. 042 * 043 * @author Rossen Stoyanchev 044 * @since 4.2 045 */ 046public class StreamingResponseBodyReturnValueHandler implements HandlerMethodReturnValueHandler { 047 048 @Override 049 public boolean supportsReturnType(MethodParameter returnType) { 050 if (StreamingResponseBody.class.isAssignableFrom(returnType.getParameterType())) { 051 return true; 052 } 053 else if (ResponseEntity.class.isAssignableFrom(returnType.getParameterType())) { 054 Class<?> bodyType = ResolvableType.forMethodParameter(returnType).getGeneric().resolve(); 055 return (bodyType != null && StreamingResponseBody.class.isAssignableFrom(bodyType)); 056 } 057 return false; 058 } 059 060 @Override 061 @SuppressWarnings("resource") 062 public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType, 063 ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { 064 065 if (returnValue == null) { 066 mavContainer.setRequestHandled(true); 067 return; 068 } 069 070 HttpServletResponse response = webRequest.getNativeResponse(HttpServletResponse.class); 071 Assert.state(response != null, "No HttpServletResponse"); 072 ServerHttpResponse outputMessage = new ServletServerHttpResponse(response); 073 074 if (returnValue instanceof ResponseEntity) { 075 ResponseEntity<?> responseEntity = (ResponseEntity<?>) returnValue; 076 response.setStatus(responseEntity.getStatusCodeValue()); 077 outputMessage.getHeaders().putAll(responseEntity.getHeaders()); 078 returnValue = responseEntity.getBody(); 079 if (returnValue == null) { 080 mavContainer.setRequestHandled(true); 081 outputMessage.flush(); 082 return; 083 } 084 } 085 086 ServletRequest request = webRequest.getNativeRequest(ServletRequest.class); 087 Assert.state(request != null, "No ServletRequest"); 088 ShallowEtagHeaderFilter.disableContentCaching(request); 089 090 Assert.isInstanceOf(StreamingResponseBody.class, returnValue, "StreamingResponseBody expected"); 091 StreamingResponseBody streamingBody = (StreamingResponseBody) returnValue; 092 093 Callable<Void> callable = new StreamingResponseBodyTask(outputMessage.getBody(), streamingBody); 094 WebAsyncUtils.getAsyncManager(webRequest).startCallableProcessing(callable, mavContainer); 095 } 096 097 098 private static class StreamingResponseBodyTask implements Callable<Void> { 099 100 private final OutputStream outputStream; 101 102 private final StreamingResponseBody streamingBody; 103 104 public StreamingResponseBodyTask(OutputStream outputStream, StreamingResponseBody streamingBody) { 105 this.outputStream = outputStream; 106 this.streamingBody = streamingBody; 107 } 108 109 @Override 110 public Void call() throws Exception { 111 this.streamingBody.writeTo(this.outputStream); 112 this.outputStream.flush(); 113 return null; 114 } 115 } 116 117}