Java tutorial
/* * Copyright 2002-2018 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.servlet.mvc.method.annotation; import java.io.IOException; import java.lang.reflect.Type; import java.util.List; import javax.servlet.http.HttpServletRequest; import org.springframework.core.Conventions; import org.springframework.core.MethodParameter; import org.springframework.core.annotation.AnnotatedElementUtils; import org.springframework.http.converter.HttpMessageConverter; import org.springframework.http.converter.HttpMessageNotReadableException; import org.springframework.http.converter.HttpMessageNotWritableException; import org.springframework.http.server.ServletServerHttpRequest; import org.springframework.http.server.ServletServerHttpResponse; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.validation.BindingResult; import org.springframework.web.HttpMediaTypeNotAcceptableException; import org.springframework.web.HttpMediaTypeNotSupportedException; import org.springframework.web.accept.ContentNegotiationManager; import org.springframework.web.bind.MethodArgumentNotValidException; import org.springframework.web.bind.WebDataBinder; import org.springframework.web.bind.annotation.RequestBody; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.bind.support.WebDataBinderFactory; import org.springframework.web.context.request.NativeWebRequest; import org.springframework.web.method.support.ModelAndViewContainer; import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver; /** * Resolves method arguments annotated with {@code @RequestBody} and handles return * values from methods annotated with {@code @ResponseBody} by reading and writing * to the body of the request or response with an {@link HttpMessageConverter}. * * <p>An {@code @RequestBody} method argument is also validated if it is annotated * with {@code @javax.validation.Valid}. In case of validation failure, * {@link MethodArgumentNotValidException} is raised and results in an HTTP 400 * response status code if {@link DefaultHandlerExceptionResolver} is configured. * * @author Arjen Poutsma * @author Rossen Stoyanchev * @author Juergen Hoeller * @since 3.1 */ public class RequestResponseBodyMethodProcessor extends AbstractMessageConverterMethodProcessor { /** * Basic constructor with converters only. Suitable for resolving * {@code @RequestBody}. For handling {@code @ResponseBody} consider also * providing a {@code ContentNegotiationManager}. */ public RequestResponseBodyMethodProcessor(List<HttpMessageConverter<?>> converters) { super(converters); } /** * Basic constructor with converters and {@code ContentNegotiationManager}. * Suitable for resolving {@code @RequestBody} and handling * {@code @ResponseBody} without {@code Request~} or * {@code ResponseBodyAdvice}. */ public RequestResponseBodyMethodProcessor(List<HttpMessageConverter<?>> converters, @Nullable ContentNegotiationManager manager) { super(converters, manager); } /** * Complete constructor for resolving {@code @RequestBody} method arguments. * For handling {@code @ResponseBody} consider also providing a * {@code ContentNegotiationManager}. * @since 4.2 */ public RequestResponseBodyMethodProcessor(List<HttpMessageConverter<?>> converters, @Nullable List<Object> requestResponseBodyAdvice) { super(converters, null, requestResponseBodyAdvice); } /** * Complete constructor for resolving {@code @RequestBody} and handling * {@code @ResponseBody}. */ public RequestResponseBodyMethodProcessor(List<HttpMessageConverter<?>> converters, @Nullable ContentNegotiationManager manager, @Nullable List<Object> requestResponseBodyAdvice) { super(converters, manager, requestResponseBodyAdvice); } @Override public boolean supportsParameter(MethodParameter parameter) { return parameter.hasParameterAnnotation(RequestBody.class); } @Override public boolean supportsReturnType(MethodParameter returnType) { return (AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ResponseBody.class) || returnType.hasMethodAnnotation(ResponseBody.class)); } /** * Throws MethodArgumentNotValidException if validation fails. * @throws HttpMessageNotReadableException if {@link RequestBody#required()} * is {@code true} and there is no body content or if there is no suitable * converter to read the content with. */ @Override public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception { parameter = parameter.nestedIfOptional(); Object arg = readWithMessageConverters(webRequest, parameter, parameter.getNestedGenericParameterType()); String name = Conventions.getVariableNameForParameter(parameter); if (binderFactory != null) { WebDataBinder binder = binderFactory.createBinder(webRequest, arg, name); if (arg != null) { validateIfApplicable(binder, parameter); if (binder.getBindingResult().hasErrors() && isBindExceptionRequired(binder, parameter)) { throw new MethodArgumentNotValidException(parameter, binder.getBindingResult()); } } if (mavContainer != null) { mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult()); } } return adaptArgumentIfNecessary(arg, parameter); } @Override protected <T> Object readWithMessageConverters(NativeWebRequest webRequest, MethodParameter parameter, Type paramType) throws IOException, HttpMediaTypeNotSupportedException, HttpMessageNotReadableException { HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class); Assert.state(servletRequest != null, "No HttpServletRequest"); ServletServerHttpRequest inputMessage = new ServletServerHttpRequest(servletRequest); Object arg = readWithMessageConverters(inputMessage, parameter, paramType); if (arg == null && checkRequired(parameter)) { throw new HttpMessageNotReadableException( "Required request body is missing: " + parameter.getExecutable().toGenericString(), inputMessage); } return arg; } protected boolean checkRequired(MethodParameter parameter) { RequestBody requestBody = parameter.getParameterAnnotation(RequestBody.class); return (requestBody != null && requestBody.required() && !parameter.isOptional()); } @Override public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws IOException, HttpMediaTypeNotAcceptableException, HttpMessageNotWritableException { mavContainer.setRequestHandled(true); ServletServerHttpRequest inputMessage = createInputMessage(webRequest); ServletServerHttpResponse outputMessage = createOutputMessage(webRequest); // Try even with null return value. ResponseBodyAdvice could get involved. writeWithMessageConverters(returnValue, returnType, inputMessage, outputMessage); } }