Environement is Null when I try to Autowire - spring

Question

I am trying to use Environment abstraction & #PropertySource of Spring to load and use properties in my #Configuration annotated classes. However I get Environment as null in my PropertyConfig class as it is accessed from another #Configuration class PersistenceConfig which used it to access the properties. Here is my relevant code :
#Configuration
#PropertySource({ "classpath:/properties/email_${environment}.properties" })
#PropertySource({ "classpath:/properties/appconfig.properties" })
#PropertySource({ "classpath:/properties/ApplicationResources.properties" })
#PropertySource({ "classpath:/properties/Database_${environment}.properties" })
#PropertySource({ "classpath:/properties/log4j.properties" })
#PropertySource({ "classpath:/properties/system.properties" })
public class PropertiesConfig {
#Autowired
private Environment env;
private static final PropertiesAccessor propertyAccessor = new PropertiesConfig().new PropertiesAccessor();
public static String getPopertyValue(String property){
return propertyAccessor.getPropertyValue(property);
}
private class PropertiesAccessor{
public String getPropertyValue(String key){
return env.getProperty(key);
}
}
}
My Other #Configuration annotated class PersistenceConfig is as follows :
#Configuration
#EnableTransactionManagement
#ComponentScan(basePackages = {"com.template"})
public class PersistenceConfig {
#Bean
public LocalSessionFactoryBean sessionFactory(){
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
sessionFactory.setDataSource(dataSource());
sessionFactory.setPackagesToScan(new String [] {"com.template.domain" });
sessionFactory.setHibernateProperties(hibernateProperties());
return sessionFactory;
}
#Bean
public BasicDataSource dataSource(){
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName(PropertiesConfig.getPopertyValue("jdbc.driverClassName"));
dataSource.setUrl(PropertiesConfig.getPopertyValue("jdbc.url"));
dataSource.setUsername(PropertiesConfig.getPopertyValue("jdbc.user"));
dataSource.setPassword(PropertiesConfig.getPopertyValue("jdbc.pass"));
return dataSource;
}
#Bean
public HibernateTransactionManager transactionManager(){
HibernateTransactionManager transactionManager = new HibernateTransactionManager();
transactionManager.setSessionFactory(sessionFactory().getObject());
return transactionManager;
}
Properties hibernateProperties(){
return new Properties() {
{
setProperty("hibernate.hbm2ddl.auto", PropertiesConfig.getPopertyValue("hibernate.hbm2ddl.auto"));
setProperty("hibernate.dialect", PropertiesConfig.getPopertyValue("hibernate.dialect"));
setProperty("hibernate.globally_quoted_identifiers", "true");
}
};
}
}
However I get NullpointerException when dataSource() method of PersistenceConfig tries to retrieve properties using PropertiesConfig.getPopertyValue("jdbc.driverClassName") because env of type Environment is null in PropertyConfig.
I am loading both classes as follows in my WebApplicationInitializer :
public class WebAppInitializer implements WebApplicationInitializer {
#Override
public void onStartup(ServletContext container) {
// Create the 'root' Spring application context
AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext();
rootContext.register(PropertiesConfig.class,SecurityConfig.class,PersistenceConfig.class,ApplicationConfig.class);
//rootContext.register(ApplicationConfig.class, PersistenceConfig.class, SecurityConfig.class); I have not added security yet
// Manage the life-cycle of the root application context
container.addListener(new ContextLoaderListener(rootContext));
// Create the dispatcher servlet's Spring application context
AnnotationConfigWebApplicationContext dispatcherServlet = new AnnotationConfigWebApplicationContext();
dispatcherServlet.register(MvcConfig.class);
// Register and map the dispatcher servlet
ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", new DispatcherServlet(dispatcherServlet));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
}
}
As far as I understand PersistenceConfig is being loaded first before PropertyConfig. Am I right? Or is there any other reason? How to make this work?

Answer 1

package com.template.config;
import javax.annotation.PostConstruct;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;import
org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
#Configuration
#PropertySource({ "classpath:/properties/email_${environment}.properties" })
#PropertySource({ "classpath:/properties/appconfig.properties" })
#PropertySource({ "classpath:/properties/ApplicationResources.properties" })
#PropertySource({ "classpath:/properties/Database_${environment}.properties"
})
#PropertySource({ "classpath:/properties/log4j.properties" })
#PropertySource({ "classpath:/properties/system.properties" })
public class PropertiesConfig {
#Autowired
private Environment env;
private static Environment environment;
#PostConstruct
public void init(){
environment = env;
System.out.println(environment == env);
}
public static String getPopertyValue(String property){
return environment.getProperty(property);
}
}

Answer 2

use #PostConstruct on a method to process what you want .Because you can't get inject bean before spring init container,the inject must be after refresh operation.
eg:
#Component
public class envConfig {
#Autowired
private Environment env;
//something want to get
private String[] profiles;
#PostConstruct
public void init(){
//get the env properties or throw injected bean to init other bean
this.profiles=env.getActiveProfiles();
}
}

Answer 3

I was facing the similar issue. There are many different questions around this problem. There are many answered. However i found the reason in below blog
https://allaboutspringframework.com/spring-fix-null-autowired-field/
In the end of this blog author has concluded the findings which is important.
Spring dependency injection only works with Spring-managed objects or Beans. If the object in which a Bean is getting injected is not a spring managed object, you will get null #Autowired fields. To fix this, make sure only the framework create and manage the related dependencies.