SpringMVC requestBody responseBody 详解
2016-12-28 15:21
363 查看
@RequestBody
作用: i) 该注解用于读取Request请求的body部分数据,使用系统默认配置的HttpMessageConverter进行解析,然后把相应的数据绑定到要返回的对象上; ii) 再把HttpMessageConverter返回的对象数据绑定到 controller中方法的参数上。使用时机:A) GET、POST方式提时, 根据request header Content-Type的值来判断: application/x-www-form-urlencoded, 可选(即非必须,因为这种情况的数据@RequestParam, @ModelAttribute也可以处理,当然@RequestBody也能处理); multipart/form-data, 不能处理(即使用@RequestBody不能处理这种格式的数据); 其他格式, 必须(其他格式包括application/json, application/xml等。这些格式的数据,必须使用@RequestBody来处理);B) PUT方式提交时, 根据request header Content-Type的值来判断: application/x-www-form-urlencoded, 必须; multipart/form-data, 不能处理; 其他格式, 必须;说明:request的body部分的数据编码格式由header部分的Content-Type指定;@ResponseBody
作用: 该注解用于将Controller的方法返回的对象,通过适当的HttpMessageConverter转换为指定格式后,写入到Response对象的body数据区。使用时机: 返回的数据不是html标签的页面,而是其他某种格式的数据时(如json、xml等)使用;HttpMessageConverter
[java] viewplaincopy<span style="font-family:Microsoft YaHei;">/** * Strategy interface that specifies a converter that can convert from and to HTTP requests and responses. * * @author Arjen Poutsma * @author Juergen Hoeller * @since 3.0 */ public interface HttpMessageConverter<T> { /** * Indicates whether the given class can be read by this converter. * @param clazz the class to test for readability * @param mediaType the media type to read, can be {@code null} if not specified. * Typically the value of a {@code Content-Type} header. * @return {@code true} if readable; {@code false} otherwise */ boolean canRead(Class<?> clazz, MediaType mediaType); /** * Indicates whether the given class can be written by this converter. * @param clazz the class to test for writability * @param mediaType the media type to write, can be {@code null} if not specified. * Typically the value of an {@code Accept} header. * @return {@code true} if writable; {@code false} otherwise */ boolean canWrite(Class<?> clazz, MediaType mediaType); /** * Return the list of {@link MediaType} objects supported by this converter. * @return the list of supported media types */ List<MediaType> getSupportedMediaTypes(); /** * Read an object of the given type form the given input message, and returns it. * @param clazz the type of object to return. This type must have previously been passed to the * {@link #canRead canRead} method of this interface, which must have returned {@code true}. * @param inputMessage the HTTP input message to read from * @return the converted object * @throws IOException in case of I/O errors * @throws HttpMessageNotReadableException in case of conversion errors */ T read(Class<? extends T> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException; /** * Write an given object to the given output message. * @param t the object to write to the output message. The type of this object must have previously been * passed to the {@link #canWrite canWrite} method of this interface, which must have returned {@code true}. * @param contentType the content type to use when writing. May be {@code null} to indicate that the * default content type of the converter must be used. If not {@code null}, this media type must have * previously been passed to the {@link #canWrite canWrite} method of this interface, which must have * returned {@code true}. * @param outputMessage the message to write to * @throws IOException in case of I/O errors * @throws HttpMessageNotWritableException in case of conversion errors */ void write(T t, MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException; } </span> 该接口定义了四个方法,分别是读取数据时的 canRead(), read() 和 写入数据时的canWrite(), write()方法。在使用 <mvc:annotation-driven />标签配置时,默认配置了RequestMappingHandlerAdapter(注意是[java] viewplaincopyByteArrayHttpMessageConverter converts byte arrays. StringHttpMessageConverter converts strings. ResourceHttpMessageConverter converts to/from org.springframework.core.io.Resource for all media types. SourceHttpMessageConverter converts to/from a javax.xml.transform.Source. FormHttpMessageConverter converts form data to/from a MultiValueMap<String, String>. Jaxb2RootElementHttpMessageConverter converts Java objects to/from XML — added if JAXB2 is present on the classpath. MappingJacksonHttpMessageConverter converts to/from JSON — added if Jackson is present on the classpath. AtomFeedHttpMessageConverter converts Atom feeds — added if Rome is present on the classpath. RssChannelHttpMessageConverter converts RSS feeds — added if Rome is present on the classpath.RequestMappingHandlerAdapter不是AnnotationMethodHandlerAdapter,详情查看spring 3.1document “16.14 Configuring Spring MVC”章节),并为他配置了一下默认的HttpMessageConverter:
ByteArrayHttpMessageConverter: 负责读取二进制格式的数据和写出二进制格式的数据;
StringHttpMessageConverter: 负责读取字符串格式的数据和写出二进制格式的数据;ResourceHttpMessageConverter:负责读取资源文件和写出资源文件数据; FormHttpMessageConverter: 负责读取form提交的数据(能读取的数据格式为 application/x-www-form-urlencoded,不能读取multipart/form-data格式数据);负责写入application/x-www-from-urlencoded和multipart/form-data格式的数据;MappingJacksonHttpMessageConverter: 负责读取和写入json格式的数据;SouceHttpMessageConverter: 负责读取和写入 xml 中javax.xml.transform.Source定义的数据;Jaxb2RootElementHttpMessageConverter: 负责读取和写入xml 标签格式的数据;AtomFeedHttpMessageConverter: 负责读取和写入Atom格式的数据;RssChannelHttpMessageConverter: 负责读取和写入RSS格式的数据;
当使用@RequestBody和@ResponseBody注解时,RequestMappingHandlerAdapter就使用它们来进行读取或者写入相应格式的数据。
HttpMessageConverter匹配过程:
@RequestBody注解时: 根据Request对象header部分的Content-Type类型,逐一匹配合适的HttpMessageConverter来读取数据;spring 3.1源代码如下:[java] viewplaincopy<span style="font-family:Microsoft YaHei;">private Object readWithMessageConverters(MethodParameter methodParam, HttpInputMessage inputMessage, Class paramType) throws Exception { MediaType contentType = inputMessage.getHeaders().getContentType(); if (contentType == null) { StringBuilder builder = new StringBuilder(ClassUtils.getShortName(methodParam.getParameterType())); String paramName = methodParam.getParameterName(); if (paramName != null) { builder.append(' '); builder.append(paramName); } throw new HttpMediaTypeNotSupportedException( "Cannot extract parameter (" + builder.toString() + "): no Content-Type found"); } List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>(); if (this.messageConverters != null) { for (HttpMessageConverter<?> messageConverter : this.messageConverters) { allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes()); if (messageConverter.canRead(paramType, contentType)) { if (logger.isDebugEnabled()) { logger.debug("Reading [" + paramType.getName() + "] as \"" + contentType +"\" using [" + messageConverter + "]"); } return messageConverter.read(paramType, inputMessage); } } } throw new HttpMediaTypeNotSupportedException(contentType, allSupportedMediaTypes); }</span> @ResponseBody注解时: 根据Request对象header部分的Accept属性(逗号分隔),逐一按accept中的类型,去遍历找到能处理的HttpMessageConverter;源代码如下:[java] viewplaincopy<span style="font-family:Microsoft YaHei;">private void writeWithMessageConverters(Object returnValue, HttpInputMessage inputMessage, HttpOutputMessage outputMessage) throws IOException, HttpMediaTypeNotAcceptableException { List<MediaType> acceptedMediaTypes = inputMessage.getHeaders().getAccept(); if (acceptedMediaTypes.isEmpty()) { acceptedMediaTypes = Collections.singletonList(MediaType.ALL); } MediaType.sortByQualityValue(acceptedMediaTypes); Class<?> returnValueType = returnValue.getClass(); List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>(); if (getMessageConverters() != null) { for (MediaType acceptedMediaType : acceptedMediaTypes) { for (HttpMessageConverter messageConverter : getMessageConverters()) { if (messageConverter.canWrite(returnValueType, acceptedMediaType)) { messageConverter.write(returnValue, acceptedMediaType, outputMessage); if (logger.isDebugEnabled()) { MediaType contentType = outputMessage.getHeaders().getContentType(); if (contentType == null) { contentType = acceptedMediaType; } logger.debug("Written [" + returnValue + "] as \"" + contentType + "\" using [" + messageConverter + "]"); } this.responseArgumentUsed = true; return; } } } for (HttpMessageConverter messageConverter : messageConverters) { allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes()); } } throw new HttpMediaTypeNotAcceptableException(allSupportedMediaTypes); }</span>补充:
MappingJacksonHttpMessageConverter 调用了 objectMapper.writeValue(OutputStream stream, Object)方法,使用@ResponseBody注解返回的对象就传入Object参数内。若返回的对象为已经格式化好的json串时,不使用@RequestBody注解,而应该这样处理:
1、response.setContentType("application/json; charset=UTF-8");
2、response.getWriter().print(jsonStr);
直接输出到body区,然后的视图为void。
相关文章推荐
- spring mvc @ResponseBody/@RequestBody 配值action直接把对象输入json格式输入到前端相关配置
- SpringMVC@requestBody @responseBody配置要点
- Spring MVC @RequestBody @ResponseBody Example
- SpringMVC @RequestBody接收Json对象字符串 @ResponseBody处理json数据类型
- SpringMVC @RequestBody与@ResponseBody注解的使用
- spring MVC @RequestParam @RequestBody @PathVariable 等参数绑定注解详解
- spring之@ModelAttribute,@RequestBody, @ResponseBody 参数传递的运用详解
- spring mvc@ResponseBody @RequestBody 的问题
- spring之@ModelAttribute,@RequestBody, @ResponseBody 参数传递的运用详解
- spring之@ModelAttribute,@RequestBody, @ResponseBody 参数传递的运用详解
- Spring MVC Json @RequestBody 和@ResponseBody
- Spring MVC @ResponseBody 提示 406 The resource identified by this request……
- springmvc @RequestParam @RequestBody @PathVariable 等参数绑定注解详解
- Spring 注解学习手札(七) 补遗——@ResponseBody,@RequestBody,@PathVariable
- SpringMVC @RequestBody接收Json对象字符串
- Spring3 MVC使用@ResponseBody产生很大的响应头
- Spring3 MVC使用@ResponseBody的乱码问题及解决办法
- spring mvc responseBody注解 乱码解决方案
- springmvc Spring3 MVC @ResponseBody返回,jquery ajax调用中文乱码问题解决