Spring PropertySourcesPlaceholderConfigurer in library - spring

Question

Background: I am writing a library that will be compiled into a JAR file. That library will be used as a dependency in a number of web applications. Both the library and the web apps are using Spring. There is an onus on the web application to run a ComponentScan on the library classes to pick up any Spring Beans / configuration.
Ask: Within the library I want to load properties from a property file using PropertySourcesPlaceholderConfigurer. Something like this:
package com.blah;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
#Configuration
#PropertySource("classpath:properties/blah.${environment}.properties")
public class AppConfig {
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
This is working fine.
Question: if the web-app that loads this library as a dependency also uses PropertySourcesPlaceholderConfigurer to load properties, will there be a conflict between the two? Will one override the other (even if the properties are different)? Or can they live in peaceful harmony side-by-side?
Using Spring 3.2.4
UPDATE
As per Bogdan Oros's answer below, it looks like this is OK i.e. they will not conflict and both sets of properties will be loaded. I created two Config files:
#Configuration
#PropertySource("classpath:properties/blah.stage1.properties")
public class BlahClientConfig1 {
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
and
#Configuration
#PropertySource("classpath:properties/blah.stage2.properties")
public class BlahClientConfig2 {
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
When I run my tests, I can successfully retrieve property values from both blah.stage1.properties and blah.stage2.properties

Answer 1

You can do an experiment a create same bean in two different configurations in same classpath and it will work
#Configuration
class AConfiguration {
#Bean
public static PropertySourcesPlaceholderConfigurer resolver() {
return new PropertySourcesPlaceholderConfigurer();
}
}
#Configuration
class B {|
#Bean
public static PropertySourcesPlaceholderConfigurer resolver() {
return new PropertySourcesPlaceholderConfigurer();
}
}
It will work correctly because spring resolves such situations.
You'll find that one bean is overridden by the other.
But if you will help spring and setup names explicitly
#Configuration
class A {
#Bean(name="resolver")
public static PropertySourcesPlaceholderConfigurer resolver() {
return new PropertySourcesPlaceholderConfigurer();
}
}
#Configuration
class B {
#Bean(name="resolver")
public static PropertySourcesPlaceholderConfigurer resolver() {
return new PropertySourcesPlaceholderConfigurer();
}
}
This situation will cause a injection failure, because it cannot decide which bean to inject.
It is explained here and also it can be configured with DefaultListableBeanFactory. Check this answer.