NumberFormatException:For input string:““ Swagger2 异常之原因与修复

swagger2版本更新到了

2.9.2

但是在进入文档页面, 控制台有时候会输出

2022-03-17 12:06:26.221  WARN 13236 --- [nio-8888-exec-7] 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) ~[na:1.8.0_301]
	at java.lang.Long.parseLong(Long.java:601) ~[na:1.8.0_301]
	at java.lang.Long.valueOf(Long.java:803) ~[na:1.8.0_301]
	at io.swagger.models.parameters.AbstractSerializableParameter.getExample(AbstractSerializableParameter.java:412) ~[swagger-models-1.5.20.jar:1.5.20]
	at sun.reflect.GeneratedMethodAccessor73.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:687) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:119) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:79) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serialize(IndexedListSerializer.java:18) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:718) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:639) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:33) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:727) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:719) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3905) [jackson-databind-2.9.7.jar:2.9.7]
	at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3219) [jackson-databind-2.9.7.jar:2.9.7]
	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_301]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_301]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_301]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_301]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:891) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) [spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_301]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_301]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.34.jar:8.5.34]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_301]

这个是一个warning异常, 不会影响任何程序, 但是看着真让人不爽 , 

先来说问题出在哪里

@ApiModelProperty    这个注解有一个属性 example, 默认值是 ""

 /**
     * A sample value for the property.
     */
    String example() default "";

swagger2 2.9.2 默认引用了 1.5.20版本的 models依赖

,

这个依赖中搜索 abstractSerializableParameter.java

@JsonProperty("x-example")
    public Object getExample() {
        if (example == null) {
            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;
    }

  

 

 如何解决呢? 

两种方法 

1 是在 注解@ApiModelProperty 中 给他的 example 给一个默认值, 

2 一劳永逸, 直接添加pom依赖(无需排除 1.5.20版本)

    io.swagger
    swagger-models
    1.5.22
 

我们再来看一下 这里新加了一个 example.isEmpty() 判断了 他是否为 "" , 不会再被catch 捕捉到了. 

 

修行不易, 你我共勉