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出现问题
SpringBoot项目中使用Swagger作为文档工具，每次在使用它的文档时，IDE工具的控制台都会打印出如下异常，会让我们感觉很不爽。
68011 [http-nio-8000-exec-6] WARN i.s.m.p.AbstractSerializableParameter - Illegal DefaultValue null for parameter type integer
java.lang.NumberFormatException: For input string: ""at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)at java.lang.Long.parseLong(Long.java:601)at java.lang.Long.valueOf(Long.java:803)at io.swagger.models.parameters.AbstractSerializableParameter.getExample(AbstractSerializableParameter.java:412)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 com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:688)at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119)at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79)at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18)at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:722)at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:643)at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:33)at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727)at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719)at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319)at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3905)at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3219)at springfox.documentation.spring.web.json.JsonSerializer.toJson(JsonSerializer.java:38)at springfox.documentation.swagger2.web.Swagger2Controller.getDocumentation(Swagger2Controller.java:105)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:189)at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797)at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897)at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)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 org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)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.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92)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.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)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.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)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:200)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)at java.lang.Thread.run(Thread.java:748)问题原因
这是由于实体类使用@ApiModelProperty时，example属性没有赋值导致的，在AbstractSerializableParameter这个类的getExample方法中会将数值属性的example的转换数值类返回，example的默认值是""，因此当example没有赋值时，会出现上面的异常。getExample方法如下
@JsonProperty("x-example")public Object getExample() {if (example == null||example.isEmpty()) {return null;}try {if (BaseIntegerProperty.TYPE.equals(type)) {return Long.valueOf(example);} else if (DecimalProperty.TYPE.equals(type)) {return Double.valueOf(example);} else if (BooleanProperty.TYPE.equals(type)) {if ("true".equalsIgnoreCase(example) || "false".equalsIgnoreCase(defaultValue)) {return Boolean.valueOf(example);}}} catch (NumberFormatException e) {LOGGER.warn(String.format("Illegal DefaultValue %s for parameter type %s", defaultValue, type), e);}return example;}解决方案
只要将每一个数值类型上@ApiModelProperty的example都赋值数字字符串即可。
但是这个解决方法比较麻烦，若将源码中的if (example == null)改为if (example == null || example.isEmpty())就可以解决问题。我下载并修改了源码，将其打包后覆盖了maven仓库的jar包，这样项目代码不需要任何修改就可以解决问题。
同时，我又查看了v1.5.21的代码 ，源码的修改是一样的。其实也可以排除1.5.20版本的swagger-models.jar，引入1.5.21版本的swagger-models.jar。但是考虑到可能由于代码改动较大引发其他问题，因此个人感觉还是在1.5.20版本代码微调最好。
最后把修复过的jar包下载链接放在这里，下载后替换本地仓库对应的文件，然后项目重新导入jar包即可。
例如，我的电脑，通过命令行进入如下目录
cd D:\developer_tools\RepMaven\io\swagger\swagger-models\1.5.20然后将两个文件复制进去覆盖原文件。
jar包下载地址：https://pan.baidu.com/s/1UhOAD2IgkORZ3OBGwmu70Q 提取码：8hdw
出自：https://blog.csdn.net/weixin_38229356/article/details/83353347