有解决办法是看注解，我的情况是参数上没有带注解，原因是接口接收参数类型是int,
int类型默认值为0 不能传空
错误情况：@RequestParam(name = “userId”, required = false, defaultValue = " ") userId: Int
正确情况：`@RequestParam(name = "userId", required = false, defaultValue = "0") userId: Int `
2022-08-05 10:14:54.157 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:845} - DispatcherServlet with name 'spring-servlet' processing GET request for [/index]
2022-08-05 10:14:54.161 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:297} - Looking up handler method for path /index
2022-08-05 10:14:54.161 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:302} - Returning handler method [public java.lang.String com.xiangshi.wzc.devloper.pc.modules.index.IndexController.index()]
2022-08-05 10:14:54.162 [http-nio-8080-exec-5] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'indexController'
2022-08-05 10:14:54.162 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:931} - Last-Modified value for [/index] is: -1
2022-08-05 10:14:54.163 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:1225} - Rendering view [org.springframework.web.servlet.view.JstlView: name 'index'; URL [/WEB-INF/views/index.jsp]] in DispatcherServlet with name 'spring-servlet'
2022-08-05 10:14:54.165 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.view.JstlView {InternalResourceView.java:166} - Forwarding to resource [/WEB-INF/views/index.jsp] in InternalResourceView 'index'
2022-08-05 10:14:54.330 [http-nio-8080-exec-5] [DEBUG] org.springframework.web.servlet.DispatcherServlet {FrameworkServlet.java:996} - Successfully completed request
2022-08-05 10:14:54.332 [http-nio-8080-exec-5] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'sqlSessionFactory'
2022-08-05 10:14:54.514 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:845} - DispatcherServlet with name 'spring-servlet' processing GET request for [/order/ExportAll]
2022-08-05 10:14:54.516 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:297} - Looking up handler method for path /order/ExportAll
2022-08-05 10:14:54.533 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:302} - Returning handler method [public org.springframework.web.servlet.ModelAndView com.xiangshi.wzc.basecore.web.controller.BaseControllerImpl.viewOne(java.lang.Long)]
2022-08-05 10:14:54.533 [http-nio-8080-exec-6] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'orderController'
2022-08-05 10:14:54.533 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:931} - Last-Modified value for [/order/ExportAll] is: -1
2022-08-05 10:14:54.538 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver {AbstractHandlerExceptionResolver.java:134} - Resolving exception from handler [public org.springframework.web.servlet.ModelAndView com.xiangshi.wzc.basecore.web.controller.BaseControllerImpl.viewOne(java.lang.Long)]: org.springframework.beans.TypeMismatchException: Failed to convert value of type [java.lang.String] to required type [java.lang.Long]; nested exception is java.lang.NumberFormatException: For input string: "ExportAll"
2022-08-05 10:14:54.538 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver {AbstractHandlerExceptionResolver.java:134} - Resolving exception from handler [public org.springframework.web.servlet.ModelAndView com.xiangshi.wzc.basecore.web.controller.BaseControllerImpl.viewOne(java.lang.Long)]: org.springframework.beans.TypeMismatchException: Failed to convert value of type [java.lang.String] to required type [java.lang.Long]; nested exception is java.lang.NumberFormatException: For input string: "ExportAll"
2022-08-05 10:14:54.539 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver {AbstractHandlerExceptionResolver.java:134} - Resolving exception from handler [public org.springframework.web.servlet.ModelAndView com.xiangshi.wzc.basecore.web.controller.BaseControllerImpl.viewOne(java.lang.Long)]: org.springframework.beans.TypeMismatchException: Failed to convert value of type [java.lang.String] to required type [java.lang.Long]; nested exception is java.lang.NumberFormatException: For input string: "ExportAll"
2022-08-05 10:14:54.539 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:1018} - Null ModelAndView returned to DispatcherServlet with name 'spring-servlet': assuming HandlerAdapter completed request handling
2022-08-05 10:14:54.539 [http-nio-8080-exec-6] [DEBUG] org.springframework.web.servlet.DispatcherServlet {FrameworkServlet.java:996} - Successfully completed request
2022-08-05 10:14:54.541 [http-nio-8080-exec-6] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'sqlSessionFactory'
2022-08-05 10:14:59.673 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:845} - DispatcherServlet with name 'spring-servlet' processing GET request for [/index]
2022-08-05 10:14:59.676 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:297} - Looking up handler method for path /index
2022-08-05 10:14:59.676 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping {AbstractHandlerMethodMapping.java:302} - Returning handler method [public java.lang.String com.xiangshi.wzc.devloper.pc.modules.index.IndexController.index()]
2022-08-05 10:14:59.676 [http-nio-8080-exec-8] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'indexController'
2022-08-05 10:14:59.677 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:931} - Last-Modified value for [/index] is: -1
2022-08-05 10:14:59.677 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.DispatcherServlet {DispatcherServlet.java:1225} - Rendering view [org.springframework.web.servlet.view.JstlView: name 'index'; URL [/WEB-INF/views/index.jsp]] in DispatcherServlet with name 'spring-servlet'
2022-08-05 10:14:59.679 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.view.JstlView {InternalResourceView.java:166} - Forwarding to resource [/WEB-INF/views/index.jsp] in InternalResourceView 'index'
2022-08-05 10:14:59.840 [http-nio-8080-exec-8] [DEBUG] org.springframework.web.servlet.DispatcherServlet {FrameworkServlet.java:996} - Successfully completed request
2022-08-05 10:14:59.843 [http-nio-8080-exec-8] [DEBUG] org.springframework.beans.factory.support.DefaultListableBeanFactory {AbstractBeanFactory.java:248} - Returning cached instance of singleton bean 'sqlSessionFactory'
解决办法：
如果你是想这个参数必须传空的情况下。最简单的解决办法为将参数类型变成integer,代码中加校验如果为空怎么处理，不为空怎么处理。
不加校验会报错
结语如果这篇文章对您有所帮助，或者有所启发的话，求一键三连：点赞、评论、收藏➕关注，您的支持是我坚持写作最大的动力。
