有没有一种方法可以注入其构造函数在micronaut中具有参数的类？

Question

Suppose I have class A.

class A {
    private String s;

    public A(String s) {
        this.s = s;
    }
}

and I want to inject A into class B.

So far, I have been injecting classes without constructor parameters like

class B {

    @Inject
    private A a;
}

But I don't know how classes with constructor parameters can be injected. How can I do this?

Answer 1

You need to prepend your constructor with @Inject to make it injectable. Please check https://docs.oracle.com/javaee/6/api/javax/inject/Inject.html for documentation and examples.

Answer 2

Instead of this:

@Singleton
class B {
    @Inject
    private A a;
}

You could have this:

@Singleton
class B {

    private A a;

    public B(A a) {
        this.a = a;
    }
}

Answer 3

I think in your example A would be a prototype bean because it has an argument that you must provide. Because you must provide the argument you can't simply inject the bean like you would a singleton. You can inject the BeanContext and call createBean . For example: beanContext.createBean(A.class, "some string value") . That would require A be annotated with @Prototype and any constructor parameters that should be provided by the creator with @Parameter .