001/* 002 * Copyright 2002-2018 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 * 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.IOException; 020import java.io.OutputStream; 021import java.io.Writer; 022 023import javax.servlet.ServletResponse; 024 025import org.springframework.core.MethodParameter; 026import org.springframework.lang.Nullable; 027import org.springframework.web.bind.support.WebDataBinderFactory; 028import org.springframework.web.context.request.NativeWebRequest; 029import org.springframework.web.method.support.HandlerMethodArgumentResolver; 030import org.springframework.web.method.support.ModelAndViewContainer; 031 032/** 033 * Resolves servlet backed response-related method arguments. Supports values of the 034 * following types: 035 * <ul> 036 * <li>{@link ServletResponse} 037 * <li>{@link OutputStream} 038 * <li>{@link Writer} 039 * </ul> 040 * 041 * @author Arjen Poutsma 042 * @author Rossen Stoyanchev 043 * @author Juergen Hoeller 044 * @since 3.1 045 */ 046public class ServletResponseMethodArgumentResolver implements HandlerMethodArgumentResolver { 047 048 @Override 049 public boolean supportsParameter(MethodParameter parameter) { 050 Class<?> paramType = parameter.getParameterType(); 051 return (ServletResponse.class.isAssignableFrom(paramType) || 052 OutputStream.class.isAssignableFrom(paramType) || 053 Writer.class.isAssignableFrom(paramType)); 054 } 055 056 /** 057 * Set {@link ModelAndViewContainer#setRequestHandled(boolean)} to 058 * {@code false} to indicate that the method signature provides access 059 * to the response. If subsequently the underlying method returns 060 * {@code null}, the request is considered directly handled. 061 */ 062 @Override 063 public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, 064 NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception { 065 066 if (mavContainer != null) { 067 mavContainer.setRequestHandled(true); 068 } 069 070 Class<?> paramType = parameter.getParameterType(); 071 072 // ServletResponse, HttpServletResponse 073 if (ServletResponse.class.isAssignableFrom(paramType)) { 074 return resolveNativeResponse(webRequest, paramType); 075 } 076 077 // ServletResponse required for all further argument types 078 return resolveArgument(paramType, resolveNativeResponse(webRequest, ServletResponse.class)); 079 } 080 081 private <T> T resolveNativeResponse(NativeWebRequest webRequest, Class<T> requiredType) { 082 T nativeResponse = webRequest.getNativeResponse(requiredType); 083 if (nativeResponse == null) { 084 throw new IllegalStateException( 085 "Current response is not of type [" + requiredType.getName() + "]: " + webRequest); 086 } 087 return nativeResponse; 088 } 089 090 private Object resolveArgument(Class<?> paramType, ServletResponse response) throws IOException { 091 if (OutputStream.class.isAssignableFrom(paramType)) { 092 return response.getOutputStream(); 093 } 094 else if (Writer.class.isAssignableFrom(paramType)) { 095 return response.getWriter(); 096 } 097 098 // Should never happen... 099 throw new UnsupportedOperationException("Unknown parameter type: " + paramType); 100 } 101 102}