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.bind.support; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.Part; import org.springframework.beans.MutablePropertyValues; import org.springframework.lang.Nullable; import org.springframework.util.LinkedMultiValueMap; import org.springframework.util.MultiValueMap; import org.springframework.util.StringUtils; import org.springframework.validation.BindException; import org.springframework.web.bind.WebDataBinder; import org.springframework.web.context.request.NativeWebRequest; import org.springframework.web.context.request.WebRequest; import org.springframework.web.multipart.MultipartException; import org.springframework.web.multipart.MultipartRequest; /** * Special {@link org.springframework.validation.DataBinder} to perform data binding * from web request parameters to JavaBeans, including support for multipart files. * * <p>See the DataBinder/WebDataBinder superclasses for customization options, * which include specifying allowed/required fields, and registering custom * property editors. * * <p>Can also used for manual data binding in custom web controllers or interceptors * that build on Spring's {@link org.springframework.web.context.request.WebRequest} * abstraction: e.g. in a {@link org.springframework.web.context.request.WebRequestInterceptor} * implementation. Simply instantiate a WebRequestDataBinder for each binding * process, and invoke {@code bind} with the current WebRequest as argument: * * <pre class="code"> * MyBean myBean = new MyBean(); * // apply binder to custom target object * WebRequestDataBinder binder = new WebRequestDataBinder(myBean); * // register custom editors, if desired * binder.registerCustomEditor(...); * // trigger actual binding of request parameters * binder.bind(request); * // optionally evaluate binding errors * Errors errors = binder.getErrors(); * ...</pre> * * @author Juergen Hoeller * @author Brian Clozel * @since 2.5.2 * @see #bind(org.springframework.web.context.request.WebRequest) * @see #registerCustomEditor * @see #setAllowedFields * @see #setRequiredFields * @see #setFieldMarkerPrefix */ public class WebRequestDataBinder extends WebDataBinder { /** * Create a new WebRequestDataBinder instance, with default object name. * @param target the target object to bind onto (or {@code null} * if the binder is just used to convert a plain parameter value) * @see #DEFAULT_OBJECT_NAME */ public WebRequestDataBinder(@Nullable Object target) { super(target); } /** * Create a new WebRequestDataBinder instance. * @param target the target object to bind onto (or {@code null} * if the binder is just used to convert a plain parameter value) * @param objectName the name of the target object */ public WebRequestDataBinder(@Nullable Object target, String objectName) { super(target, objectName); } /** * Bind the parameters of the given request to this binder's target, * also binding multipart files in case of a multipart request. * <p>This call can create field errors, representing basic binding * errors like a required field (code "required"), or type mismatch * between value and bean property (code "typeMismatch"). * <p>Multipart files are bound via their parameter name, just like normal * HTTP parameters: i.e. "uploadedFile" to an "uploadedFile" bean property, * invoking a "setUploadedFile" setter method. * <p>The type of the target property for a multipart file can be Part, MultipartFile, * byte[], or String. The latter two receive the contents of the uploaded file; * all metadata like original file name, content type, etc are lost in those cases. * @param request request with parameters to bind (can be multipart) * @see org.springframework.web.multipart.MultipartRequest * @see org.springframework.web.multipart.MultipartFile * @see javax.servlet.http.Part * @see #bind(org.springframework.beans.PropertyValues) */ public void bind(WebRequest request) { MutablePropertyValues mpvs = new MutablePropertyValues(request.getParameterMap()); if (isMultipartRequest(request) && request instanceof NativeWebRequest) { MultipartRequest multipartRequest = ((NativeWebRequest) request) .getNativeRequest(MultipartRequest.class); if (multipartRequest != null) { bindMultipart(multipartRequest.getMultiFileMap(), mpvs); } else { HttpServletRequest servletRequest = ((NativeWebRequest) request) .getNativeRequest(HttpServletRequest.class); if (servletRequest != null) { bindParts(servletRequest, mpvs); } } } doBind(mpvs); } /** * Check if the request is a multipart request (by checking its Content-Type header). * @param request request with parameters to bind */ private boolean isMultipartRequest(WebRequest request) { String contentType = request.getHeader("Content-Type"); return (contentType != null && StringUtils.startsWithIgnoreCase(contentType, "multipart")); } private void bindParts(HttpServletRequest request, MutablePropertyValues mpvs) { try { MultiValueMap<String, Part> map = new LinkedMultiValueMap<>(); for (Part part : request.getParts()) { map.add(part.getName(), part); } map.forEach((key, values) -> { if (values.size() == 1) { Part part = values.get(0); if (isBindEmptyMultipartFiles() || part.getSize() > 0) { mpvs.add(key, part); } } else { mpvs.add(key, values); } }); } catch (Exception ex) { throw new MultipartException("Failed to get request parts", ex); } } /** * Treats errors as fatal. * <p>Use this method only if it's an error if the input isn't valid. * This might be appropriate if all input is from dropdowns, for example. * @throws BindException if binding errors have been encountered */ public void closeNoCatch() throws BindException { if (getBindingResult().hasErrors()) { throw new BindException(getBindingResult()); } } }