How to inject Spring Bean for factory method requiring MyClass.class parameter

Question

I'm trying to inject a java.util.prefs.Preferences bean in to my master controller. The controller looks like:

@Controller
class MyController {
    @Autowired
    private Preferences preferences;
}

The application-context.xml file creates the bean for java.util.prefs.Preferences. It uses a factory method so I have the following entry for creating the bean:

<bean id="preferences" class="java.util.prefs.Preferences" factory-method="userNodeForPackage" />

Preferences.userNodeForPackage(param) takes for a parameter the class related to the Preference. In this case Spring needs to create the bean by performing the call:

Preferences.userNodeForPackage(MyController.class);

How can a class be passed in to a spring bean instantiated with a factory method? Thanks

Environment information:

Java 7
Spring 3.1

Sotirios Delimanolis · Accepted Answer · 2013-08-26T14:30:47.220

24

You can specify the constructor-arg element

<bean id="preferences" class="java.util.prefs.Preferences" factory-method="userNodeForPackage">
    <constructor-arg type="java.lang.Class" value="com.path.MyController" />
</bean>

This is explained in the official documentation here, section 5.4.1.

Arguments to the static factory method are supplied via elements, exactly the same as if a constructor had actually been used. The type of the class being returned by the factory method does not have to be of the same type as the class that contains the static factory method, although in this example it is. An instance (non-static) factory method would be used in an essentially identical fashion (aside from the use of the factory-bean attribute instead of the class attribute), so details will not be discussed here.

edited Aug 26 '13 at 14:30

answered Aug 26 '13 at 14:18

Sotirios Delimanolis

274,122
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He needs to provide argument as parameter to `userNodeForPackage()` method, not constructor of `Preferences` – Nandkumar Tekale Aug 26 '13 at 14:31
3

@NandkumarTekale Read the quote and the documentation. That's how you do it when you've specified `factory-method` attribute. – Sotirios Delimanolis Aug 26 '13 at 14:32
This technique also works to use a static field value as a constructor argument! – kevinarpe Apr 29 '22 at 13:32

Nandkumar Tekale · Answer 2 · 2013-08-26T14:59:22.427

Well I don't know the xml based configuration way but I can tell you how you can instantiate it via Configuration class.

@Configuration
public class Config {
    @Bean(name="preferences")
    public java.util.prefs.Preferences preferences() {
        // init
        return java.util.prefs.Preferences.userNodeForPackage(YourExpectedClass.class);
    }
}

P.S. :

You will need to add your configuration class/package for scanning either in web.xml if you are using complete annotation based approach [contextClass=org.springframework.web.context.support.AnnotationConfigWebApplicationContext] or in your config file as below :

<context:component-scan base-package="com.comp.prod.conf" />

+1 Should probably mention in your answer it comes from the spring-context artifact in Maven. — James Watkins, Oct 26 '14 at 18:03

Prabhakaran Ramaswamy · Answer 3 · 2013-08-26T14:42:03.223

 public class Preferences
 {  
     SomeBean someBean;

     public void setSomeBean(SomeBean someBean){
            this.someBean = someBean;
     }  

     public static Preferences createSampleBeanWithIntValue(SomeBean someBean)
     {
         Preferences preferences= new Preferences();
         preferences.setSomeBean(someBean);
         return preferences;
     }
}

  <bean id="someBean" class="java.util.prefs.SomeBean"/>

 <bean id="preferences" class="java.util.prefs.Preferences" factory-method="userNodeForPackage" > 

    <constructor-arg ref="someBean "/>       
 </bean>

Please see the reference

http://www.skorks.com/2008/10/are-you-using-the-full-power-of-spring-when-injecting-your-dependencies/

score 0 · Answer 4 · answered Jun 08 '16 at 12:10

first create the bean of 'Preferences' class either using xml file or using annotation.
then you can use this <context:annotation-config> if you created bean using xml configuration to activate the @Autowired annotation functionality
(or )

<context:component-scan base-package="com.estudo.controller" />
if you created bean using annotations.
Note : define the above tags in the spring servlet xml file

score 0 · Answer 5 · answered Mar 25 '17 at 05:10

Spring framework provides facility to inject bean using factory method. To do so, we can use two attributes of bean element.

factory-method: represents the factory method that will be invoked to inject the bean. factory-bean: represents the reference of the bean by which factory method will be invoked. It is used if factory method is non-static. A method that returns instance of a class is called factory method.

public class A {  
public static A getA(){//factory method  
    return new A();  
}  
}

score -1 · Answer 6 · answered Aug 26 '13 at 14:19

-1

Can you try making "preferences" a property of "MyController". Something like

<bean id="MyController" class="com.your.package.MyController">
    <property name="preferences" ref="preferences" />
</bean>

and then have the getter and setter method for preferences in MyController.

I think this should work.

answered Aug 26 '13 at 14:19

Ankit

1,250
16
23

1

OP's problem isn't autowiring the object. The problem is specifying and argument to a static factory-method. – Sotirios Delimanolis Aug 26 '13 at 14:31

How to inject Spring Bean for factory method requiring MyClass.class parameter

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