How to Inject property values into a static property or method of an enum or normal class using Spring?

Question

I am in serious trouble due to a situation. Here's my problem.

PROBLEM: Need to inject a simple static string field /property in an enum class FROM spring config XML. Here's some similar code I tested :

public enum AppProperty {
    NUMBER_OF_ACCOUNTS("accounts"), NUMBER_OF_USERS("users");

    private AppProperty(String cuser) {
        this.current_user = cuser;
    }

    private final String current_user;
    private static final String PROPERTY_FILE = "application.properties";

    static {
        init();
    }

    public static String appContext; // **PROBLEM** : need to populate this ONLY
                                        // from spring config XML via property
                                        // injection.

    public static void init() {

        if (appContext.equals("statement")) {
            // do something..... generate statement et...
        } else {
            // do some other process... generate balance etc
        }
    }

    ..........  few more static methods...
    ..... few more non-static methods
}// end of class

I tried mostly everything for this simple problem but strangely nothing seems working for Spring 3.1 :(

Injecting a property via property setter etc not working at all.. String appContext always turns out NULL... tried ..

 @Autowired(required = true)
   setAppConfig( String context){
AppProperty.appContext = context
)
}

and tried every wiring and autowiring.... mostly either returns null or exception "AppProperties.init() cannot be called as no default constructor ...." (even tried a default constructor for god's sake but don't work...!!!

So thought lets get this single property from a property file and get it done but that also don't work and same problem.

<context:component-scan base-package="com.my.package" /> 
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <list>
            <value>classpath:application.properties</value>
        </list>
    </property>
</bean>

and used this in java class over propert .. @Value("${appContext}")

This also demands to instantiate AppProperty.init() which is not achievable by me.

I think the ONLY way to inject a property from config xml seems using MethodInvokingFactoryBean (How to make spring inject value into a static field)

I tried this also but my hard luck it's also not working!!!! Only thing i think I may do wrong is not using the @value tag properly

In config file I used :

<bean class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="staticMethod" value="com.my.package.setAppContext"/>
    <property name="arguments"  value ="testing"/>
</bean>

In java file AppProperty I used

public static  String appContext;
  public void setAppContext(String appContext) {
    AppProperty.appContext = appContext;
    }

Request : Please provide your answer with exact code which I can use as I may be using right solution but Syntex and configuration are missing .. Shall I use @Component over my AppProperty class!! etc... please provide details and get my blessings...

Note: I NEED to Inject this property via Spring Config XML so that I can change the context at runtime.. As I am not allowed to change existing implementation of this class. So please don't suggest to remove enum class with something else... Thanks in advance.

Answer 1

After no help from SO ..did some some self struggle and found following solution , if it could help somebody:

I realized that Spring Context was getting initialized even before the static block.

So to get the context indirectly , created a class to get the context.

public class SpringBean  {

@Autowired
private  ApplicationContext applicationContext;

private static SpringBean bean = new SpringBean();

public static SpringBean getInstance() {
    return bean;
}


public ApplicationContext getApplicationContext() {
    return applicationContext;
}

public Object getBean(String beanName) {
    if (applicationContext == null) {
        throw new IllegalStateException("No context  initialised.");
    }
    return applicationContext.getBean(beanName);
} 

} 

Note: Same class could be created implimenting ApplicationContextAware interface by SpringBean.

declare this in spring config file as :

  <context:annotation-config/>      
  <bean    class="com.db.icestation.server.pd.common.SpringBean"
    factory-method="getInstance"/>

Also created a String SWITCH variable 'appContext' in spring config , this is the varibale which was my objective to inject in AppProperty class.

   <bean id="appContext" class="java.lang.String"> 
   <constructor-arg value="Atlast..Injecting this string in a static block..."/> 
    </bean> 

Finally.... get this value in your main class "AppProperty" above .....

public static String appContext;    // My problem .. see question above...now resolved

 static{
  appContext = SpringBean.getInstance().getBean("appContext").toString();
  init();
  }