问题

最近从将springfox-swagger2 2.8.0升级到2.9.0版本，后台报如下错误：

java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_181]
	at java.lang.Long.parseLong(Long.java:601) ~[na:1.8.0_181]
	at java.lang.Long.valueOf(Long.java:803) ~[na:1.8.0_181]
	at io.swagger.models.parameters.AbstractSerializableParameter.getExample(AbstractSerializableParameter.java:412) ~[swagger-models-1.5.20.jar:1.5.20]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:633) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:672) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:672) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:616) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:519) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:31) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:672) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:678) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:157) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:130) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3631) [apihelper-1.0.0-all.jar:na]
	at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:2998) [apihelper-1.0.0-all.jar:na]
	at springfox.documentation.spring.web.json.JsonSerializer.toJson(JsonSerializer.java:38) [springfox-spring-web-2.9.2.jar:null]
	at springfox.documentation.swagger2.web.Swagger2Controller.getDocumentation(Swagger2Controller.java:105) [springfox-swagger2-2.9.2.jar:null]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189) [spring-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) [spring-web-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) [spring-webmvc-5.1.5.RELEASE.jar:5.1.5.RELEASE]

./gradlew dependencies

查看依赖

+--- io.springfox:springfox-swagger2:2.9.2
|    +--- io.swagger:swagger-annotations:1.5.20
|    +--- io.swagger:swagger-models:1.5.20

这里我们可以看到springfox-swagger2版本2.9.2使用的io.swagger是1.5.20。

解决

排除springfox-swagger2版本2.9.2中的io.swagger是1.5.20版本，我们显示使用io.swagger是1.5.22版本，即io.swagger的最新版本。

build.gralde

implementation group: 'io.springfox', name: 'springfox-swagger2', version: '2.9.2'
implementation group: 'io.swagger', name: 'swagger-annotations', version: '1.5.22'
implementation group: 'io.swagger', name: 'swagger-models', version: '1.5.22'

./gradlew dependencies

再次查看依赖：

+--- io.springfox:springfox-swagger2:2.9.2
|    +--- io.swagger:swagger-annotations:1.5.20 -> 1.5.22
|    +--- io.swagger:swagger-models:1.5.20 -> 1.5.22

现在springfox-swagger2版本2.9.2使用的io.swagger是1.5.22版本了。