SpringBoot 中的 Kotlin - `init` 块的初始化顺序

Question

the following situation is in Kotlin and SpringBoot context. I would like to know if the initialization of Kotlin's init block is executed before or after all dependency injection is executed.

Intuitively init is executed when the class is created, so it does not wait for the die DI-framework to be ready. This can lead to potential problems.

Does anyone have more information or documentation?

Answer 1

Just taking Spring-Boot as an example:

package com.example.demo

import org.springframework.stereotype.Controller
import org.springframework.stereotype.Service
import org.springframework.web.bind.annotation.GetMapping

@Controller
class MyController(private val service: MyService) {

    init {
        println("MyController Init")
    }

    @GetMapping("/")
    fun foo(): String = "bar"
}

@Service
class MyService {

    init {
        println("MyService Init")
    }
}

will print the following lines:

MyService Init
MyController Init

So the dependency will be initialized first. Afterwards the init of the class will be called. The init functions will be executed before the constructor of a Kotlin class.