錯誤:ajax的post方法調用后台controller方法時報錯:415 (Unsupported Media Type)。下面是錯誤時的代碼
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:"失敗"}); } } 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:對后台spring mvc不熟,只是有個概念服務器應該接收到了http請求,只是因為某種原因沒有進入controller,而提前被攔截處理了。然后就開始找http處理的源頭,笨辦法,從HttpServlet.service開始找 -> DispatcherServlet.doDispatch,找到關鍵的處理方法handle
拋出錯誤的位置
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()) { //由於controller調用的這個方法參數加了@RequestBody,ann.required()這個為true就不走這里, 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(類);
@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); } } } //這里是報錯位置 throw new HttpMediaTypeNotSupportedException(contentType, this.allSupportedMediaTypes);//沒有找到參數對應的轉換器就報錯 }
原因:@RequestBody
a) 該注解用於讀取Request請求的body部分數據,根據request的header部分的Content-Type類型,匹配HttpMessageConverter進行解析,然后把相應的數據綁定到要返回的對象上;
b) 再把HttpMessageConverter返回的對象數據綁定到 controller中方法的參數上。
前台沒有注明后台解析參考的content-type,默認為application/x-www-form-urlencoded ,同時參數是對象也是不是json字符串,后台找不到解析方法。
解決:content-type為application/json格式的數據可以被jackson解讀(這里在canread判斷時用到),json對應jackson處理請求中的參數,jackson的參數應該是json字符串(enum JsonToken 這里有關於解析的字符串格式token的枚舉內容: START_OBJECT("{").....), 而不是application/x-www-form-urlencoded編碼的字符串“year=2017“。
所以前端請求需改為:
ajax(url,JSON.stringify(params),function(result){ console.log(result); },"application/json")
正確解析時,調用的轉換器是jackson。
備注:調用到參數解析的調用棧
可參考:https://blog.csdn.net/mingtianhaiyouwo/article/details/51445345
1.瀏覽器請求時沒有設置Content-Type為Json,對於瀏覽器來說就是要把POST的內容放到jsonData屬性中,而不是params。
2.第三方工具沒有設置Content-Type的功能,默認的是Content-Type: application/x-www-form-urlencoded