注入静态字段Kotlin / Spring Boot

Question

Im trying to inject a value into a static field in Kotlin, but I`m not having success.

I know a workaround with Java, so in Kotlin, what`s the equivalent for this Java code?

@Component
public class GlobalValue {

    public static String DATABASE;

    @Value("${mongodb.db}")
    public void setDatabase(String db) {
        DATABASE = db;
    }
}

Answer 1

Thought this was gonna work:

@Component
class GlobalValue {
    companion object {
        @JvmStatic
        lateinit var database: String
        @Value("\${myprop.testing2}") set
    }
}

But it doesn't, for some reason, possibly, because generated setter is final , or because it goes through Companion object, I don't know.

This works tho:

@Component
class GlobalValue {
    companion object {
        @JvmField
        var database: String = "test"
    }

    @Value("\${myprop.testing2}")
    fun setDatabase(db: String) {
        database = db
    }
}

Note the \\ in @Value - it's because otherwise we would have a conflict with the language itself, such construct is already there. Also, you need to specify a default value, lateinit is impossible with @JvmField .

Answer 2

Theoretically, the following should be equivalent:

@Component
class GlobalValue {
    companion object {
        @JvmField
        lateinit var DATABASE: String
    }

    @Value("\${mongodb.db}")
    fun setDatabase(db: String) {
        DATABASE = db;
    }
}