使用RestTemplate访问微服务时报错org.springframework.web.client.HttpClientErrorException: 400 null，如何解决答案

【问题标题】：How to fix the error org.springframework.web.client.HttpClientErrorException: 400 null, when using RestTemplate to access Microservice使用RestTemplate访问微服务时报错org.springframework.web.client.HttpClientErrorException: 400 null，如何解决
【发布时间】：2020-02-06 08:33:09
【问题描述】：

在我的 java 代码中，我尝试使用 RestTemplate 访问微服务，如下所示：

    headers = new HttpHeaders();
    headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
    headers.setContentType(MediaType.APPLICATION_JSON);
    entity = new HttpEntity<BigDecimal>(c.getDocumentId(),headers);                     
    ResponseEntity<String> response =    restTemplate.exchange("http://localhost:8082/document-external-id", HttpMethod.POST, entity, String.class);
    String externalId= response.getBody();

在服务器端，我有这个：

@RequestMapping(value="/document-external-id", method=RequestMethod.POST)

String getExternalDocumentId(@RequestBody  BigDecimal documentId)
{
    System.out.println("Documents External Id Microservice called.....Params are:"+documentId);

    Documents document =documentsService.findDocumentById(documentId);//invoke the method to get the document

    System.out.println("Documents External Id microservice is DONE!.......................................Returning value:"+document.getExternalDocumentId());

    return document.getExternalDocumentId();

}

当我运行我的代码时，这是客户端错误的输出，出现在这一行：

ResponseEntity<String> response =    restTemplate.exchange("http://localhost:8082/document-external-id", HttpMethod.POST, entity, String.class);

错误是：

org.springframework.web.client.HttpClientErrorException: 400 null
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:85)
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:708)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:661)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:621)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:539)
    at ae.gov.adm.saeed.web.controller.util.CircularsControllerUtil.circularListView(CircularsControllerUtil.java:151)
    at ae.gov.adm.saeed.web.controller.CircularsController.viewCircularList(CircularsController.java:58)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at ae.gov.adm.saeed.web.security.AuthFilter.doFilter(AuthFilter.java:335)
    at ae.gov.adm.saeed.web.security.AuthFilter.doFilter(AuthFilter.java:610)
    at ae.gov.adm.common.web.filter.AbstractFilter.doFilter(AbstractFilter.java:47)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:651)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:417)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:754)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1376)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)
400 null

在服务器端，我有以下带有警告消息的输出：

Documents External Id Microservice called.....Params are:9191
2020-02-06 12:18:19.086  WARN 1752 --- [nio-8082-exec-5] org.hibernate.orm.deprecation            : HHH90000022: Hibernate's legacy org.hibernate.Criteria API is deprecated; use the JPA javax.persistence.criteria.CriteriaQuery instead
Hibernate: select this_.id as id1_0_0_, this_.doc_master_id as doc_master_id2_0_0_, this_.entry_id as entry_id3_0_0_, this_.external_doc_id as external_doc_id4_0_0_, this_.file_path as file_path5_0_0_, this_.name as name6_0_0_, this_.server_address as server_address7_0_0_, this_.type as type8_0_0_, this_.upload_date as upload_date9_0_0_ from mu_documents this_ where this_.id=?
Documents External Id microservice is DONE!.......................................Returning value:{A66CD1F8-839F-432F-9C9C-4EAE961A8F46}
2020-02-06 12:18:19.135  WARN 1752 --- [nio-8082-exec-8] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotReadableException: Required request body is missing: java.lang.String ae.gov.adm.DocumentsMicroservice.getExternalDocumentId(java.math.BigDecimal)]

如何修复错误？谢谢。

【问题讨论】：

您的服务以 400-Bad Request 响应，因为缺少必需的请求正文：java.lang.String ae.gov.adm.DocumentsMicroservice.getExternalDocumentId(java.math.BigDecimal)我>。因此，您的请求似乎缺少正确的请求正文。我会检查服务真正定义为正文的内容，并将其与您发送的正文进行比较。
正如您在上面看到的，服务请求 BigDecimal 作为参数，而我发送 BigDecimal 作为参数。还能缺少什么？以及在哪里检查服务方法参数以外的地方。抱歉，我是新手。
顺便说一句，当我删除@RequestBody 错误消失了，但服务没有收到客户端发送的参数。参数值为null
如果您删除@RequestBody，则不需要RequestBody，这就是它“有效”的原因。您是否检查了 c.getDocumentId() 是否为空？
DefaultHandlerExceptionResolver 处理异常并打印警告消息。您还可以在那里打印堆栈跟踪（如果您可以访问代码）。我试图重现您的错误，但无济于事。我复制粘贴了您的代码，除了 documentsService.findDocumentById(documentId) 和 Document 类。也许你的错误就在那里？

标签： java json spring http httpresponse

【解决方案1】：

事实证明，某些文档 id 的值 null 会导致问题。也许，因为@RequestBody 不接受空值。

这是解决问题的更新：

  if(documentId!=null)
                        {
                            headers = new HttpHeaders();
                            headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
                            headers.setContentType(MediaType.APPLICATION_JSON);
                            entity = new HttpEntity<BigDecimal>(documentId,headers);                        
                            ResponseEntity<String> response =    restTemplate.exchange("http://localhost:8082/document-name", HttpMethod.POST, entity, String.class);
                            documentName= response.getBody();
                        }

【讨论】：

【解决方案2】：

你有没有试过这样的注释：

  @PostMapping(value = "/document-external-id", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
public String getExternalDocumentId(@RequestBody  BigDecimal documentId){

       System.out.println("Documents External Id Microservice called.....Params are:"+documentId);

       Documents document =documentsService.findDocumentById(documentId);//invoke the method to get the document

       System.out.println("Documents External Id microservice is DONE!.......................................Returning value:"+document.getExternalDocumentId());

       return document.getExternalDocumentId();
}

【讨论】：