Spring: Make sure a particular bean gets initialized first

Question

I have a library doing runtime setup and configuration of log4j (no log4j.properties or log4j.xml). I have defined a bean with class called MyLoggerFactory and I want this t

Answer 1

Your options are:

1. Use @DependsOn annotation(available after spring 3.0.x) or depends-on xml-attribute and make all classes that use the configured loggers depend on the logger factory
2. Make the factory an actual factory for loggers, and inject the loggers into the beans instead of calling the factory directly – this is essentially the same as option 1, except the dependency is implied. This is the option I'd recommend.
3. Move the initialisation code to a part of your code where call order is specified – the main() method, or a ServletContextListener registered before the one that initializes Spring.

There is no way to explicitly define initialisation order in Spring and likely never will be – there's no way to define useful semantics for it considering you can load many application context configuration files which might have conflicting orderings. I've yet to see a case where the desired ordering couldn't be achieved by refactoring your code to better conform to the dependency injection pattern.

Answer 2

This is a feature requested but not resolved. You can use depends-on but is too verbose. Follow tis link for more information: https://jira.springsource.org/browse/SPR-3948

Answer 3

You can @Autowired an @Configuration in the main @Configuration

@Configuration
@Import(BusinessConfig.class, EarlyBeans.class)
public class MainConfiguration {

    // The bean defined in EarlyBean will be loaded before 
    // most beans references by MainConfiguration, 
    // including those coming from BusinessConfig
    @Autowired
    EarlyBeans earlyBeans;

}

@Configuration
public class EarlyBeans {
    @Bean
    public Void earlyBean(ApplicationContext appContext) {
        // .getBeansOfType allows to call for beans which might not exist
        appContext.getBeansOfType(TechnicalBean.class);

        return null;
    }

}

Answer 4

You can split your application context as multiple and use import in main application context. You can put the main environment settings first in the order of import and then continue adding other files.

It could be like below.

<!-- Import environment properties settings. -->
<import resource="Spring-Env.xml"/>
<!-- Import All the other Application contexts. -->
<import resource="Spring-MainApplicationContext.xml"/>