CODEWITHSUNDEEP
spring
Ambuj Jauhari
Ambuj Jauhari

Reputation: 1299

SPRING: Using Autowiring inside a bean created by factory instantaion in spring

Hi I am unable to autowire my bean inside another bean which is instantiated using a factory method.

class A{

    private String name;

    //getters and setters for name
}

class B{

    @Autowired
    private A x;

    private B(String Gender, String jobProfile){
        String name = x.getName();
       //some code
    }

    public static getInstance(String Gender,String jobProfile){
        //some code for instantiation.
    }
}

Now when i create the instance of class B using factory method, from some different class. Autowiring does not happens, it returns NULL i.e. x is coming as null. Hence i am getting null pointer exceptions when calling getName on this

Have you any solution for it ?? or i am doing somethign wroing ??

Upvotes: 3

Views: 11360

Answers (2)

Nazarii Bardiuk
Nazarii Bardiuk

Reputation: 4342

In the @Autowired documentation is said that fields are autowired after object construction.

So in your code Spring has not jet injected x when you try to use x.getName() in constructor.

You have several options:

  • move A x into the constructor
  • move initialization logic out of the constructor

Upvotes: 1

Xstian
Xstian

Reputation: 8282

When you create an object by new, autowire\inject don't work...

as workaround you can try this:

and create an istance in this way

context.getBean("myBean");

PROTOTYPE : This scopes a single bean definition to have any number of object instances.

Config

<bean id="a" class="..." >
<bean id="b" class="..." scope="prototype">
<bean id="factory" class="..." >

Factory class

public class Factory implements ApplicationContextAware {

    private ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext applicationContext)throws BeansException {
        this.applicationContext = applicationContext;
    }

    public B createClass(){
        context.getBean("b");
    }

    public B createClass(Object... args){
        context.getBean("b",args);
    }

    }

in this way Autowired annotation works fine.

As Javadocs say getBean ..

/**
     * Return an instance, which may be shared or independent, of the specified bean.
     * <p>Allows for specifying explicit constructor arguments / factory method arguments,
     * overriding the specified default arguments (if any) in the bean definition.
     * @param name the name of the bean to retrieve
     * @param args arguments to use if creating a prototype using explicit arguments to a
     * static factory method. It is invalid to use a non-null args value in any other case.
     * @return an instance of the bean
     * @throws NoSuchBeanDefinitionException if there is no such bean definition
     * @throws BeanDefinitionStoreException if arguments have been given but
     * the affected bean isn't a prototype
     * @throws BeansException if the bean could not be created
     * @since 2.5
     */
    Object getBean(String name, Object... args) throws BeansException;

Upvotes: 1

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