错误:ajax的post方法调用后台controller方法时报错:415 (Unsupported Media Type)。下面是错误时的代码
前端:
var url ="xxx/xxQuery.action"; var params={ year:'2017' } ajax(url,params,function(result){ console.log(result); }) function ajax(url,params,callback,contentType){ var ajaxoptions={ url:url, data:params, type:"POST", dataType:"json", // contentType:",//application/x-www-form-urlencoded application/json" success:function(res){ callback(res); }, error:function(){ callback({success:false,description:"失败"}); } } if(contentType!=undefined){ ajaxoptions=$.extend(ajaxoptions,{contentType:contentType}) } $.ajax(ajaxoptions); }
后台:
@RequestMapping(value = { "/xxx/xxQuery.action" }) @ResponseBody public Map<String, Object> xxQuery(Model model, HttpServletRequest request, @RequestBody ORParameter parameter) { ........ return result; }
我的思路:对后台spring mvc不熟,只是有个概念服务器应该接收到了http请求,只是因为某种原因没有进入controller,而提前被拦截处理了。然后就开始找http处理的源头,笨办法,从HttpServlet.service开始找 -> DispatcherServlet.doDispatch,找到关键的处理方法handle
抛出错误的位置
package org.springframework.web.servlet.mvc.method.annotation. RequestResponseBodyMethodProcessor; @Override protected <T> Object readWithMessageConverters(NativeWebRequest webRequest, MethodParameter methodParam, Type paramType) throws IOException, HttpMediaTypeNotSupportedException { HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class); HttpInputMessage inputMessage = new ServletServerHttpRequest(servletRequest); RequestBody ann = methodParam.getParameterAnnotation(RequestBody.class); if (!ann.required()) { //由于controller调用的这个方法参数加了@RequestBody,ann.required()这个为true就不走这里, InputStream inputStream = inputMessage.getBody(); if (inputStream == null) { return null; } else if (inputStream.markSupported()) { inputStream.mark(1); if (inputStream.read() == -1) { return null; } inputStream.reset(); } else { final PushbackInputStream pushbackInputStream = new PushbackInputStream(inputStream); int b = pushbackInputStream.read(); if (b == -1) { return null; } else { pushbackInputStream.unread(b); } inputMessage = new ServletServerHttpRequest(servletRequest) { @Override public InputStream getBody() { // Form POST should not get here return pushbackInputStream; } }; } } return super.readWithMessageConverters(inputMessage, methodParam, paramType); } package org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver(类);
@SuppressWarnings("unchecked") protected <T> Object readWithMessageConverters(HttpInputMessage inputMessage, MethodParameter methodParam, Type targetType) throws IOException, HttpMediaTypeNotSupportedException { MediaType contentType; try { contentType = inputMessage.getHeaders().getContentType(); } catch (InvalidMediaTypeException ex) { throw new HttpMediaTypeNotSupportedException(ex.getMessage()); } if (contentType == null) { contentType = MediaType.APPLICATION_OCTET_STREAM; } Class<?> contextClass = methodParam.getDeclaringClass(); Map<TypeVariable, Type> map = GenericTypeResolver.getTypeVariableMap(contextClass); Class<T> targetClass = (Class<T>) GenericTypeResolver.resolveType(targetType, map); for (HttpMessageConverter<?> converter : this.messageConverters) { if (converter instanceof GenericHttpMessageConverter) { GenericHttpMessageConverter genericConverter = (GenericHttpMessageConverter) converter; if (genericConverter.canRead(targetType, contextClass, contentType)) { if (logger.isDebugEnabled()) { logger.debug("Reading [" + targetType + "] as "" + contentType + "" using [" + converter + "]"); } return genericConverter.read(targetType, contextClass, inputMessage); } } if (targetClass != null) { if (converter.canRead(targetClass, contentType)) { if (logger.isDebugEnabled()) { logger.debug("Reading [" + targetClass.getName() + "] as "" + contentType + "" using [" + converter + "]"); } return ((HttpMessageConverter<T>) converter).read(targetClass, inputMessage); } } } //这里是报错位置 throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);//没有找到参数对应的转换器就报错 }
原因:@RequestBody
a) 该注解用于读取Request请求的body部分数据,根据request的header部分的Content-Type类型,匹配HttpMessageConverter进行解析,然后把相应的数据绑定到要返回的对象上;
b) 再把HttpMessageConverter返回的对象数据绑定到 controller中方法的参数上。
前台没有注明后台解析参考的content-type,默认为application/x-www-form-urlencoded ,同时参数是对象也是不是json字符串,后台找不到解析方法。
解决:content-type为application/json格式的数据可以被jackson解读(这里在canread判断时用到),json对应jackson处理请求中的参数,jackson的参数应该是json字符串(enum JsonToken 这里有关于解析的字符串格式token的枚举内容: START_OBJECT("{").....), 而不是application/x-www-form-urlencoded编码的字符串“year=2017“。
所以前端请求需改为:
ajax(url,JSON.stringify(params),function(result){ console.log(result); },"application/json")
正确解析时,调用的转换器是jackson。
备注:调用到参数解析的调用栈
可参考:https://blog.csdn.net/mingtianhaiyouwo/article/details/51445345
1.浏览器请求时没有设置Content-Type为Json,对于浏览器来说就是要把POST的内容放到jsonData属性中,而不是params。
2.第三方工具没有设置Content-Type的功能,默认的是Content-Type: application/x-www-form-urlencoded