我有一个使用 Spring 公开一些 RestServices 的服务器。我有大约 20 种服务，它们几乎总是做同样的事情：获取、列出、保存......
在所有这些服务中，我有一个与其他服务不同的请求：
@RequestMapping(value = {"/{id}"}, method = RequestMethod.GET)
@ResponseBody
public Line get(@PathVariable(value = "id") int id) {
return lineService.getById(id);
}
问题 ：
当我重新启动服务器并第一次调用此特定请求时，我收到 406 错误代码。
之后，所有其他调用都以成功结束，返回格式良好的 JSON 和 HTTP 200 代码等。
请求的 Accept Headers 包含“application/json”。
我试图在 requestMapping 上添加这个：
produces="application/json"
似乎在某个地方，服务器在第一次失败后调整了响应的内容/类型，但我绝对不明白在哪里。
我尝试使用 tomcat 和 jetty 作为后端服务器，但两者都有错误。
有任何想法吗？
编辑 ：
经过进一步调查，我在 tomcat 日志中检测到了这种差异。在第一次调用（HTTP 406）时，我可以看到：
09:33:58.637 [http-bio-9090-exec-3] DEBUG o.s.o.jpa.EntityManagerFactoryUtils - Closing JPA EntityManager
09:33:58.637 [http-bio-9090-exec-3] DEBUG o.s.w.a.FixedContentNegotiationStrategy - Requested media types is application/json (based on default MediaType)
09:33:58.654 [http-bio-9090-exec-3] DEBUG o.s.w.s.m.m.a.ExceptionHandlerExceptionResolver - Resolving exception from handler [public com.mycompany.myproject.dto.MyClass com.mycompany.myproject.controller.patrimoine.LigneMobileController.get(int)]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.w.s.m.a.ResponseStatusExceptionResolver - Resolving exception from handler [public com.mycompany.myproject.dto.MyClass com.mycompany.myproject.controller.patrimoine.LigneMobileController.get(int)]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.w.s.m.s.DefaultHandlerExceptionResolver - Resolving exception from handler [public com.mycompany.myproject.dto.MyClass com.mycompany.myproject.controller.patrimoine.LigneMobileController.get(int)]: org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.web.servlet.DispatcherServlet - Null ModelAndView returned to DispatcherServlet with name 'springServlet': assuming HandlerAdapter completed request handling
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.web.servlet.DispatcherServlet - Successfully completed request
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.s.w.a.ExceptionTranslationFilter - Chain processed normally
09:33:58.657 [http-bio-9090-exec-3] DEBUG o.s.s.w.c.SecurityContextPersistenceFilter - SecurityContextHolder now cleared, as request processing completed
在第二次通话中，我可以看到这一点（差异从第 2 行开始）：
09:50:52.384 [http-bio-9090-exec-7] DEBUG o.s.o.jpa.EntityManagerFactoryUtils - Closing JPA EntityManager
09:50:52.385 [http-bio-9090-exec-7] DEBUG o.s.w.s.m.m.a.RequestResponseBodyMethodProcessor - Written [com.mycompany.myproject.dto.patrimoine.mobile.ligne.LigneMobile@18949ad1] as "application/json;charset=UTF-8" using [org.springframework.http.converter.json.MappingJacksonHttpMessageConverter@32a64bcd]
09:50:52.385 [http-bio-9090-exec-7] DEBUG o.s.web.servlet.DispatcherServlet - Null ModelAndView returned to DispatcherServlet with name 'springServlet': assuming HandlerAdapter completed request handling
09:50:52.385 [http-bio-9090-exec-7] DEBUG o.s.web.servlet.DispatcherServlet - Successfully completed request
09:50:52.385 [http-bio-9090-exec-7] DEBUG o.s.s.w.a.ExceptionTranslationFilter - Chain processed normally
09:50:52.385 [http-bio-9090-exec-7] DEBUG o.s.s.w.c.SecurityContextPersistenceFilter - SecurityContextHolder now cleared, as request processing completed
因此，在第一种情况下，我在尝试将对象转换为 JSON 时收到一些 HttpMediaTypeNotAcceptableException。