[JAVA] DI SessionScope Bean in Spring Boot 2 Filter

Preface

Recently I'm doing web development with Spring Boot. I would like to manage sessions with @SessionScope as much as possible instead of using HttpSession directly. I investigated how to reference @SeesionScope beans in Filter.

Constitution

Sample code and projects are available on GitHub. Please have a look if you like.

Conclusion

There is a lot of information and the contents of the investigation will be described later, but I will write from the conclusion first. A simple configuration could only be achieved with @Autowired.

UserInfo.kt(@SessionScope)

@Component
@SessionScope
data class UserInfo(
        var name: String?
) : Serializable

SessionFilter.kt(OncePerRequestFilter)

@Component
class SessionFilter : OncePerRequestFilter() {

    //It was the same as DI with Controller.
    @Autowired
    private lateinit var userInfo: UserInfo

    override fun doFilterInternal(request: HttpServletRequest, response: HttpServletResponse, filterChain: FilterChain) {
        println("name: ${userInfo.name}")
        filterChain.doFilter(request, response)
    }
}

Background to the conclusion

Although it is not a book of Spring Boot 2, it seems to be famous in the Spring area Introduction to Spring Java application development with Spring Framework DelegatingFilterProxy A method has been proposed to define in XML to register a filter in. Therefore, I decided to try the method using DelegatingFilterProxy first. I don't like the method of defining in XML, so I rewrote it in Java Config (Kotlin).

SessionFilter.kt(OncePerRequestFilter)

@Component("SessionFilter")  //I was specifying a name.
class SessionFilter : OncePerRequestFilter() {
    :
    : (Same as the code posted in the conclusion)
    :
}

WebInitializer.kt

class WebInitializer : AbstractAnnotationConfigDispatcherServletInitializer() {
    override fun getRootConfigClasses(): Array<Class<*>>? {
        return null
    }

    override fun getServletMappings(): Array<String> {
        return arrayOf("/")
    }

    override fun getServletFilters(): Array<Filter> {
        val dfp = DelegatingFilterProxy().apply {
            // SessionFilter.kt@Set the name specified in Component.
            setTargetBeanName("SessionFilter")
        }
        return arrayOf(dfp)
    }

    override fun getServletConfigClasses(): Array<Class<*>>? {
        return arrayOf(WebConfig::class.java)
    }
}

I've seen some FAQs that can't DI in `Filter, and the above countermeasures have been introduced, but in my environment Conclusion / e02cad0e81ad8ba9d73e #% E7% B5% 90% E8% AB% 96), I achieved the purpose without this description. There may be a difference between Spring MVC and Spring Boot 2, but there is too little information to investigate.

At the end

Compared to other well-known web frameworks (though I don't think it's a minor web framework), I got the impression that Spring-related information is often complicated and legacy. Therefore, I posted an article for the first time in a long time, hoping that it would be useful for something.