spring - Kotlin 无法在使用 @Configuration @EnableWebMvc 注释的类中创建 @Autowired 字段

Question

Autowired 字段在初始化项目时为 null:

package com.lynas.config

import org.springframework.stereotype.Component
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter
import javax.servlet.http.HttpServletRequest
import javax.servlet.http.HttpServletResponse


@Component
open class InterceptorConfig : HandlerInterceptorAdapter() {

    override fun preHandle(request: HttpServletRequest, response: HttpServletResponse, handler: Any?): Boolean {

        return true
    }
}



package com.lynas.config

import org.springframework.beans.factory.annotation.Autowired
import org.springframework.context.annotation.ComponentScan
import org.springframework.context.annotation.Configuration
import org.springframework.web.servlet.config.annotation.EnableWebMvc
import org.springframework.web.servlet.config.annotation.InterceptorRegistry
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter

@Configuration
@EnableWebMvc
@ComponentScan("com.lynas")
open class WebConfig() : WebMvcConfigurerAdapter() {

    // this field show null
    @Autowired
    lateinit var interceptorConfig: InterceptorConfig

    override fun addInterceptors(registry: InterceptorRegistry) {
        registry.addInterceptor(interceptorConfig)
    }

}

lateinit var interceptorConfig: InterceptorConfig 在我运行应用程序时为 null。如何解决这个问题？

完整代码https://github.com/lynas/kotlinSpringBug

Answer 1

尝试 @field:Autowired lateinit var interceptorConfig 或 @set:Autowired 这将告诉 kotlin 编译器将注释显式地放在字段/ setter 上。默认情况下，它将它们放置在“属性”上，这是仅限 kotlin 的构造，Java 可能无法访问它。引用 kotlin docs here