解决Swagger报错java.lang.NumberFormatException: For input string: ““

页面请求swagger-ui页面后端控制台会打印出以下问题：

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)

从日志定位可以看出跟踪源码：

可以看出来在return Long.valueOf(example)中由于example是空值，所以在转换的时候出现了异常。

总结

io.springfox:springfox-swagger2:2.9.2中依赖了swagger-models的1.5.20版本，我们可以排除springfox-swagger2中的swagger-models依赖，导入io.swagger:swagger-models的1.5.21版本即可。

方法：

<!-- 解决Swagger报错java.lang.NumberFormatException: For input string: "" -->
		<dependency>
			<groupId>io.springfox</groupId>
			<artifactId>springfox-swagger2</artifactId>
			<version>2.9.2</version>
			<exclusions>
				<exclusion>
					<groupId>io.swagger</groupId>
					<artifactId>swagger-annotations</artifactId>
				</exclusion>
				<exclusion>
					<groupId>io.swagger</groupId>
					<artifactId>swagger-models</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>io.swagger</groupId>
			<artifactId>swagger-annotations</artifactId>
			<version>1.5.21</version>
		</dependency>
		<dependency>
			<groupId>io.swagger</groupId>
			<artifactId>swagger-models</artifactId>
			<version>1.5.21</version>
		</dependency>
		<dependency>
			<groupId>io.springfox</groupId>
			<artifactId>springfox-swagger-ui</artifactId>
			<version>2.9.2</version>
		</dependency>