Swagger2 异常 NumberFormatException:For input string:""

项目中引入Swagger2时，有时会出现数字转化异常，如图；

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:395)
    at sun.reflect.GeneratedMethodAccessor208.invoke(Unknown Source)
    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:664)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689)
    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:704)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
    at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:633)
    at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:536)
    at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:30)
    at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:704)
    at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:689)
    at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:155)
    at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:292)
    at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:3697)
    at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3073)
    at springfox.documentation.spring.web.json.JsonSerializer.toJson(JsonSerializer.java:38)
    at springfox.documentation.swagger2.web.Swagger2Controller.getDocumentation(Swagger2Controller.java:105)

这是因为Swagger2中  @ApiModelProperties 如果为数字类型，但添加注解后，又不指定example的值，会默认为"",swagger在后续处理的时候强行转化空字符串就会抛出异常。这也是Swagger2的bug。

有两种处理方式：

第1种：

logging.level.io.swagger.models.parameters.AbstractSerializableParameter=ERROR

将swagger的级别设置为error，（不太推荐）

第2种：

           
    io.swagger            
    swagger-annotations           
    1.5.21       
        
            
    io.swagger            
    swagger-models            
    1.5.21        

将swagger的 annotations以及models 替换为1.5.21版本即可。(推荐)