Spring Boot 2 can't read property as String

Question

While migrating a Spring Boot application from Spring Boot 1.4.0 to Spring Boot 2, I started getting errors on trying to read a property from my .properties file.

In the properties file, the property is defined as:

environment=dev

And in one of my classes, I am importing the property through the @Value annotation, like this:

@Getter
@Setter
public class CustomUserFilter extends SwitchUserFilter {
    ...
    @Value("${environment}")
    private String environment;
    ...

The class above overrides org.springframework.security.web.authentication.switchuser.SwitchUserFilter, to enable users to switch roles.

Until Spring Boot 1.4.0, I was able to import this property in my class as a String. However, ever since migrating to Spring Boot 2, I get the following compile-time error:

Error:(43, 20) java: getEnvironment() in demo.config.CustomUserFilter cannot implement getEnvironment() in org.springframework.core.env.EnvironmentCapable return type java.lang.String is not compatible with org.springframework.core.env.Environment

I'm not sure why this is happening. I also tried changing the type of this variable to Environment (org.springframework.core.env.Environment) (as shown below):

...
@Value("${environment}")
private Environment environment;
...

, but then I started getting the following error:

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'switchUserFilter': Unsatisfied dependency expressed through field 'environment'; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'org.springframework.core.env.Environment'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.springframework.core.env.Environment': no matching editors or conversion strategy found
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:370)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1336)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:572)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.getOrderedBeansOfType(ServletContextInitializerBeans.java:226)
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:182)
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAsRegistrationBean(ServletContextInitializerBeans.java:177)
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.addAdaptableBeans(ServletContextInitializerBeans.java:159)
    at org.springframework.boot.web.servlet.ServletContextInitializerBeans.<init>(ServletContextInitializerBeans.java:81)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getServletContextInitializerBeans(ServletWebServerApplicationContext.java:261)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:234)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:185)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:154)
    ... 52 more
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert value of type 'java.lang.String' to required type 'org.springframework.core.env.Environment'; nested exception is java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.springframework.core.env.Environment': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:77)
    at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:60)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1089)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1062)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:581)
    ... 70 more
Caused by: java.lang.IllegalStateException: Cannot convert value of type 'java.lang.String' to required type 'org.springframework.core.env.Environment': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:299)
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:117)
    at org.springframework.beans.TypeConverterSupport.doConvert(TypeConverterSupport.java:70)
    ... 74 more

Any clues as to what could be wrong? I am using Spring Boot 2.0, Spring 5, Java 11, and Tomcat 8.5.35. Thanks!

Answer 1

The problem was unrelated to Spring Boot. My class above extends org.springframework.security.web.authentication.switchuser.SwitchUserFilter, which further extends org.springframework.web.filter.GenericFilterBean. This GenericFilterBean class also has an attribute private Environment environment;. Further, this class was modified in Spring 5 release to include a getter method on this attribute. Spring 5 introduced a getEnvironment() with return type Environment in class GenericFilterBean, which was conflicting with my getEnvironment() with return type String.

To avoid this conflict, I simply changed the name of my attribute from environment to env and things worked after that.

Answer 2

Add @Component to your class and try that