NullPointerException swagger

异常信息

异常关键字空指针 NullPointerException swagger



java.lang.NullPointerException: null
	at springfox.documentation.swagger2.mappers.RequestParameterMapper.bodyParameter(RequestParameterMapper.java:264)
	at springfox.documentation.swagger2.mappers.RequestParameterMapper.mapParameter(RequestParameterMapper.java:149)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2Mapper.beforeMappingOperations(ServiceModelToSwagger2Mapper.java:125)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2MapperImpl.mapOperation(ServiceModelToSwagger2MapperImpl.java:109)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2Mapper.mapOperations(ServiceModelToSwagger2Mapper.java:270)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2Mapper.lambda$mapApiListings$2(ServiceModelToSwagger2Mapper.java:258)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
	at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)
	at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:270)
	at java.util.TreeMap$ValueSpliterator.forEachRemaining(TreeMap.java:2897)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.forEachOrdered(ReferencePipeline.java:423)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2Mapper.mapApiListings(ServiceModelToSwagger2Mapper.java:253)
	at springfox.documentation.swagger2.mappers.ServiceModelToSwagger2MapperImpl.mapDocumentation(ServiceModelToSwagger2MapperImpl.java:48)
	at springfox.documentation.swagger2.web.Swagger2ControllerWebMvc.getDocumentation(Swagger2ControllerWebMvc.java:99)
	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:150)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:655)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.springframework.cloud.sleuth.instrument.web.servlet.TracingFilter.doFilter(TracingFilter.java:89)
	at org.springframework.cloud.sleuth.autoconfig.instrument.web.LazyTracingFilter.doFilter(TraceWebServletConfiguration.java:114)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at com.payment.common.filter.RequestInputStreamCacheFilter.doFilterInternal(RequestInputStreamCacheFilter.java:29)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:96)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)

开始分析

抛出空指针的地方是一个 RequestParameterMapper 请求参数的映射的类;

抛出异常基本上就是我们的方法注解定义错了;要做的就是检查注解，但是对于有很多方法的一个一个检查太麻烦了；
所以需要能定位到时那个方法的注解出现了问题;

跟着异常信息向上找

有个类是 ServiceModelToSwagger2Mapper 里面的一个方法 beforeMappingOperations 在映射操作之前

可以看到里面有个循环；这个循环应该是遍历了一个一个方法获取信息之后生成文档；

现在要做的就是把断点打到循环里。

@BeforeMapping
  @SuppressWarnings("deprecation")
  void beforeMappingOperations(
      @MappingTarget Operation target,
      springfox.documentation.service.Operation source,
      @Context ModelNamesRegistry modelNamesRegistry) {
    List<io.swagger.models.parameters.Parameter> parameters = new ArrayList<>();
    if (useModelV3) {
      for (RequestParameter each : source.getRequestParameters()) {
      	//添加断点=== 查看each 信息后 放行

        parameters.addAll(Mappers.getMapper(RequestParameterMapper.class)
            .mapParameter(each, modelNamesRegistry));
      }
      target.setResponses(mapResponses(source.getResponses(), modelNamesRegistry));
    } else {
      for (springfox.documentation.service.Parameter each : source.getParameters()) {
        parameters.add(Mappers.getMapper(ParameterMapper.class).mapParameter(each));
      }
      target.setResponses(mapResponseMessages(source.getResponseMessages()));
    }
    target.setParameters(parameters);
  }

重复执行通过断点快速看到 each 的信息并记住，之后放行.直到抛出异常，然后可以根据记得注解的参数信息全局搜索；
可大致定位到时那个方法的问题;

比如问题:

使用@ApiImplicitParams 标注参数，却用 @RequestBody 接收会报错;

@ApiImplicitParams(
value = {
@ApiImplicitParam(name = “x”, value = “b”, required = true,example = “x”),
@ApiImplicitParam(name = “x”, value = “b”, required = true,example = “x”)
}
)
method(@RequestBody XX xx);

原文链接：https://blog.csdn.net/qq_34279995/article/details/123108608