Spring annotation @Autowired inside methods

Question

@Autowired can be used with constructors, setter and class variables.

How can I use the @Autowired annotation inside a method or any other scope.? I tried the following, but it produces compilation errors. For example

public classs TestSpring {  
  public void method(String param){  
    @Autowired
    MyCustomObjct obj; 

    obj.method(param);
  }
}  

If this is impossible, is there any other way to achieve ? (I used Spring 4.)

Answer 1

The @Autowired annotation is itself annotated with

@Target({ElementType.CONSTRUCTOR, ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE})

This means it can only be used to annotate constructors, fields, methods, or other annotation types. It can't be used on local variables.

Even if it could, there's nothing Spring or any runtime environment could do about it because reflection doesn't provide any hooks into method bodies. You wouldn't be able to access that local variable at runtime.

You'll have to move that local variable to a field and autowire that.

Answer 2

If what you are looking for is IoC in method you can do this:

Helper2.java class

public class Helper2 {

    @Autowired
    ApplicationContext appCxt;

    public void tryMe() {
        Helper h = (Helper) appCxt.getBean("helper");
        System.out.println("Hello: "+h);
    }
}

spring.xml file notice the user of <context:annotation-config />

<beans ...>
    <context:annotation-config />
    <bean id="helper" class="some_spring.Helper" />
    <bean id="helper2" class="some_spring.Helper2" />
</beans>

log output

2017-07-06 01:37:05 DEBUG DefaultListableBeanFactory:249 - Returning cached instance of singleton bean 'helper2'
2017-07-06 01:37:05 DEBUG DefaultListableBeanFactory:249 - Returning cached instance of singleton bean 'helper'
Hello: some_spring.Helper@431e34b2