Java tutorial
/* * Copyright 2012-2014 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 * * http://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.data.rest.webmvc.config; import java.io.IOException; import java.io.Serializable; import java.util.List; import javax.servlet.http.HttpServletRequest; import org.springframework.core.MethodParameter; import org.springframework.data.mapping.PersistentEntity; import org.springframework.data.repository.support.RepositoryInvoker; import org.springframework.data.rest.webmvc.IncomingRequest; import org.springframework.data.rest.webmvc.PersistentEntityResource; import org.springframework.data.rest.webmvc.PersistentEntityResource.Builder; import org.springframework.data.rest.webmvc.ResourceNotFoundException; import org.springframework.data.rest.webmvc.RootResourceInformation; import org.springframework.data.rest.webmvc.json.DomainObjectReader; import org.springframework.data.rest.webmvc.support.BackendIdHandlerMethodArgumentResolver; import org.springframework.http.MediaType; import org.springframework.http.converter.HttpMessageConverter; import org.springframework.http.converter.HttpMessageNotReadableException; import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter; import org.springframework.http.server.ServerHttpRequest; import org.springframework.http.server.ServletServerHttpRequest; import org.springframework.util.Assert; import org.springframework.web.bind.support.WebDataBinderFactory; import org.springframework.web.context.request.NativeWebRequest; import org.springframework.web.method.support.HandlerMethodArgumentResolver; import org.springframework.web.method.support.ModelAndViewContainer; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; /** * Custom {@link HandlerMethodArgumentResolver} to create {@link PersistentEntityResource} instances. * * @author Jon Brisbin * @author Oliver Gierke */ public class PersistentEntityResourceHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver { private static final String ERROR_MESSAGE = "Could not read an object of type %s from the request!"; private static final String NO_CONVERTER_FOUND = "No suitable HttpMessageConverter found to read request body into object of type %s from request with content type of %s!"; private final RootResourceInformationHandlerMethodArgumentResolver resourceInformationResolver; private final BackendIdHandlerMethodArgumentResolver idResolver; private final DomainObjectReader reader; private final List<HttpMessageConverter<?>> messageConverters; /** * Creates a new {@link PersistentEntityResourceHandlerMethodArgumentResolver} for the given * {@link HttpMessageConverter}s and {@link RootResourceInformationHandlerMethodArgumentResolver}.. * * @param messageConverters must not be {@literal null}. * @param resourceInformationResolver must not be {@literal null}. * @param idResolver must not be {@literal null}. * @param reader must not be {@literal null}. */ public PersistentEntityResourceHandlerMethodArgumentResolver(List<HttpMessageConverter<?>> messageConverters, RootResourceInformationHandlerMethodArgumentResolver resourceInformationResolver, BackendIdHandlerMethodArgumentResolver idResolver, DomainObjectReader reader) { Assert.notEmpty(messageConverters, "MessageConverters must not be null or empty!"); Assert.notNull(resourceInformationResolver, "RootResourceInformationHandlerMethodArgumentResolver must not be empty!"); Assert.notNull(idResolver, "BackendIdHandlerMethodArgumentResolver must not be null!"); Assert.notNull(reader, "DomainObjectReader must not be null!"); this.messageConverters = messageConverters; this.resourceInformationResolver = resourceInformationResolver; this.idResolver = idResolver; this.reader = reader; } /* * (non-Javadoc) * @see org.springframework.web.method.support.HandlerMethodArgumentResolver#supportsParameter(org.springframework.core.MethodParameter) */ @Override public boolean supportsParameter(MethodParameter parameter) { return PersistentEntityResource.class.isAssignableFrom(parameter.getParameterType()); } /* * (non-Javadoc) * @see org.springframework.web.method.support.HandlerMethodArgumentResolver#resolveArgument(org.springframework.core.MethodParameter, org.springframework.web.method.support.ModelAndViewContainer, org.springframework.web.context.request.NativeWebRequest, org.springframework.web.bind.support.WebDataBinderFactory) */ @Override @SuppressWarnings({ "unchecked", "rawtypes" }) public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception { RootResourceInformation resourceInformation = resourceInformationResolver.resolveArgument(parameter, mavContainer, webRequest, binderFactory); HttpServletRequest nativeRequest = webRequest.getNativeRequest(HttpServletRequest.class); ServletServerHttpRequest request = new ServletServerHttpRequest(nativeRequest); IncomingRequest incoming = new IncomingRequest(request); Class<?> domainType = resourceInformation.getDomainType(); MediaType contentType = request.getHeaders().getContentType(); for (HttpMessageConverter converter : messageConverters) { if (!converter.canRead(PersistentEntityResource.class, contentType)) { continue; } Serializable id = idResolver.resolveArgument(parameter, mavContainer, webRequest, binderFactory); Object objectToUpdate = getObjectToUpdate(id, resourceInformation); boolean forUpdate = false; Object entityIdentifier = null; PersistentEntity<?, ?> entity = resourceInformation.getPersistentEntity(); if (objectToUpdate != null) { forUpdate = true; entityIdentifier = entity.getIdentifierAccessor(objectToUpdate).getIdentifier(); } Object obj = read(resourceInformation, incoming, converter, objectToUpdate); if (obj == null) { throw new HttpMessageNotReadableException(String.format(ERROR_MESSAGE, domainType)); } if (entityIdentifier != null) { entity.getPropertyAccessor(obj).setProperty(entity.getIdProperty(), entityIdentifier); } Builder build = PersistentEntityResource.build(obj, entity); return forUpdate ? build.build() : build.forCreation(); } throw new HttpMessageNotReadableException(String.format(NO_CONVERTER_FOUND, domainType, contentType)); } /** * Reads the given {@link ServerHttpRequest} into an object of the type of the given {@link RootResourceInformation}, * potentially applying the content to an object of the given id. * * @param information must not be {@literal null}. * @param request must not be {@literal null}. * @param converter must not be {@literal null}. * @param id must not be {@literal null}. * @return */ private Object read(RootResourceInformation information, IncomingRequest request, HttpMessageConverter<Object> converter, Object objectToUpdate) { // JSON + PATCH request if (request.isPatchRequest() && converter instanceof MappingJackson2HttpMessageConverter) { if (objectToUpdate == null) { throw new ResourceNotFoundException(); } ObjectMapper mapper = ((MappingJackson2HttpMessageConverter) converter).getObjectMapper(); Object result = readPatch(request, mapper, objectToUpdate); return result; // JSON + PUT request } else if (converter instanceof MappingJackson2HttpMessageConverter) { ObjectMapper mapper = ((MappingJackson2HttpMessageConverter) converter).getObjectMapper(); return objectToUpdate == null ? read(request, converter, information) : readPutForUpdate(request, mapper, objectToUpdate); } // Catch all return read(request, converter, information); } private Object readPatch(IncomingRequest request, ObjectMapper mapper, Object existingObject) { try { JsonPatchHandler handler = new JsonPatchHandler(mapper, reader); return handler.apply(request, existingObject); } catch (Exception o_O) { if (o_O instanceof HttpMessageNotReadableException) { throw (HttpMessageNotReadableException) o_O; } throw new HttpMessageNotReadableException(String.format(ERROR_MESSAGE, existingObject.getClass()), o_O); } } private Object readPutForUpdate(IncomingRequest request, ObjectMapper mapper, Object existingObject) { try { JsonPatchHandler handler = new JsonPatchHandler(mapper, reader); JsonNode jsonNode = mapper.readTree(request.getBody()); return handler.applyPut((ObjectNode) jsonNode, existingObject); } catch (Exception o_O) { throw new HttpMessageNotReadableException(String.format(ERROR_MESSAGE, existingObject.getClass()), o_O); } } private Object read(IncomingRequest request, HttpMessageConverter<Object> converter, RootResourceInformation information) { try { return converter.read(information.getDomainType(), request.getServerHttpRequest()); } catch (IOException o_O) { throw new HttpMessageNotReadableException(String.format(ERROR_MESSAGE, information.getDomainType()), o_O); } } /** * Returns the object to be updated identified by the given id using the given {@link RootResourceInformation}. * * @param id can be {@literal null}. * @param information must not be {@literal null}. * @return */ private static Object getObjectToUpdate(Serializable id, RootResourceInformation information) { if (id == null) { return null; } RepositoryInvoker invoker = information.getInvoker(); return invoker.invokeFindOne(id); } }