Kotlin SpringMVC HandlerInterceptor – Spring Boot

Kotlin SpringMVC HandlerInterceptor – Spring Boot

In the tutorial, JavaSampleApproach will show you how to create a Kotlin SpringMVC HandlerInterceptor that provides a mechanism to intercept requests {preProcessing, postProcessing and afterCompletion} with SpringBoot.

I. Technologies

– Java 1.8
– Maven 3.6.1
– Spring Tool Suite – Version 3.9.0.RELEASE
– Spring Boot – 1.5.9.RELEASE
– Kotlin 1.1.61

II. Goal

We use SpringToolSuite to create a Kotlin SpringBoot project as below structure:

Use HandlerInterceptor to intercept requests:

@Component
class LogInterceptor: HandlerInterceptor{
    
    val log = LoggerFactory.getLogger(LogInterceptor::class.java);
    
    override fun preHandle(request: HttpServletRequest, response: HttpServletResponse, dataObject: Any) : Boolean{
        log.info("1. from PreHandle method.")
        return true
    }
    
    override fun postHandle(request: HttpServletRequest, response: HttpServletResponse, dataObject: Any, model: ModelAndView?){
        log.info("3. from PostHandle method.")
    }
    
    override fun afterCompletion(request: HttpServletRequest, response: HttpServletResponse, dataObject: Any, e: Exception?) {
        log.info("4. from AfterCompletion method - Request Completed!")
    }
}

With a simple RestAPI:

@GetMapping("/hello")
fun hello(): String{
    log.info("2. Actual Excuting - Welcome to @GetMapping: /hello!")
    return "Hello World!"
}

We make a request http://localhost:8080/hello, see logs:

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Kotlin SpringMVC HandlerInterceptor – Spring Boot