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What difference does #EnableConfigurationProperties make if a bean is already annotated with #ConfigurationProperties?

The Spring Boot documentation says that to use the #ConfigurationProperties annotation
You also need to list the properties classes to register in the
#EnableConfigurationProperties annotation, as shown in the following
example:
and gives this code:
#Configuration
#EnableConfigurationProperties(AcmeProperties.class)
public class MyConfiguration {
}
But in the very next paragraph says:
Even if the preceding configuration creates a regular bean for
AcmeProperties, we recommend that #ConfigurationProperties only deal
with the environment and, in particular, does not inject other beans
from the context. Having said that, the #EnableConfigurationProperties
annotation is also automatically applied to your project so that any
existing bean annotated with #ConfigurationProperties is configured
from the Environment.
Suggesting that listing a #ConfigurationProperties bean under an #EnableConfigurationProperties annotation is not necessary.
So which is it? Experimentally, I've seen that if I annotate a bean with #ConfigurationProperties it gets properties injected to it as expected without needing to list it in #EnableConfigurationProperties, but if this is the case then why list anything that has a #ConfigurationProperties annotation under #EnableConfigurationProperties, as is shown in the documentation? Does it make any kind of difference?

As M. Deinum referred #EnableConfigurationProperties Is for enabling support of #ConfigurationProperties. If you take a look to the annotation Java Doc you can see:
Enable support for ConfigurationProperties annotated beans. ConfigurationProperties beans can be registered in the standard way (for example using Bean #Bean methods) or, for convenience, can be specified directly on this annotation. [...]
For example, let's say you have a class whose responsibility is to read and store information from your application.yml / application.properties that is required to make a connection to different databases. You annotate it with #ConfigurationProperties.
Then, you typically have a #Configuration annotated class that provides a DataSource #Bean to your application. You can use the #EnableConfigurationProperties to link it to the #ConfigurationProperties class and init your data sources accordingly.
Here is a small example:
application.yml
data-sources:
db1:
url: "jdbc:postgresql://localhost:5432}/db1"
username: test
password: test
db2:
url: "jdbc:postgresql://localhost:5432}/db2"
username: test
password: test
DataSourcesConfiguration
#ConfigurationProperties
public class DataSourcesConfiguration {
private Map<String, BasicDataSource> dataSources;
public void setDataSources(Map<String, BasicDataSource> dataSources) {
this.dataSources = dataSources;
}
Map<String, BasicDataSource > getDataSources() {
return dataSources;
}
}
DataSourceConnectionConfiguration
#Configuration
#EnableConfigurationProperties(DataSourcesConfiguration.class)
public class DatabaseConnectionConfiguration implements Provider<Connection> {
private DataSourcesConfiguration dataSourcesConfiguration;
public DatabaseConnectionConfiguration(DataSourcesConfiguration dataSourcesConfiguration) {
this.dataSourcesConfiguration = dataSourcesConfiguration;
}
#Bean
public DataSource dataSource() {
// Use dataSourcesConfiguration to create application data source. E.g., a AbstractRoutingDataSource..
}
}

It took me a while to reach to this post but would like to add here so that others may get benefited.
#ConfigurationProperties - Used to bind a class with an externalized property file. Very powerful and must be used to separate out bean classes with configuration entity class.
#Configuration - Creates a Spring bean of configuration stereotype.
#EnableConfigurationProperties - Creates a binding between a configuration entity class and Spring configuration stereotype so that after injection within a service properties can be retrieved easily.

If we look at the code below:
#Configuration #EnableConfigurationProperties #ConfigurationProperties(prefix="ar1")
public class ar1Settings { }
#Configuration tells Spring to treat this as a configuration class and register it as a Bean
#EnableConfigurationProperties tells Spring to treat this class as a consumer of application.yml/properties values
#ConfigurationProperties tells Spring what section this class represents.
My understanding is that if you don't need to specify the section of the property file, then #ConfigurationProperties can be omitted.

#EnableConfigurationProperties imports EnableConfigurationPropertiesRegistrar which enables support for #ConfigurationProperties annotated beans.
#ConfigurationProperties is an annotation for externalized configuration, it is to be applied to a bean configuration class or method annotated with #Bean eg
#ConfigurationProperties(prefix = "some-prefix")
public SomePrefix prefixBean() {
return new SomePrefix();
}
To load the properties and bind them to properties within the method or the class that match the prefix.
ps: some-prefix binds to SomePrefix because of spring's support for Relaxed binding.
Before springboot 2.2, You could do either of the following:
#Configuration
#ConfigurationProperties(prefix = "some-prefix")
public class ConfigProperties {
//...some code
}
or
#Configuration
#EnableConfigurationProperties(SomeClassToBeBounded.class)
public class ConfigProperties {
along with
#ConfigurationProperties(prefix = "some-prefix")
public class SomeClassToBeBounded{
//...some code
}
From springboot 2.2
You can do it in a much easier way:
#ConfigurationProperties(prefix = "some-prefix")
#ConfigurationPropertiesScan
public class ConfigProperties {
//...some code
}
With this, the classpath scanner enabled by #SpringBootApplication finds the ConfigProperties class, even though we didn't annotate this class with #Component.

#refreshScope and #PropertySource how to?

Anybody know if #RefreshScope, applied to class for reloading properties/yml files dinamically works with a configuration class annotated only with #PropertySource?
I have to refresh an external configuration file, but i cant do something like :
#Bean
#RefreshScope
public FileProperties refreshListConfig() {
return new FileProperties(); //why ?
}
#Configuration //Configuration or new instance as above?
#PropertySource("file:${path.properties}")
#ConfigurationProperties(prefix="multitenancy")
public class FileProperties {
private List<DirProps> dir =new ArrayList<DirProps>();
private String tenantsFilePath;
..
class DirProps { ..}
...
}
I know that #RefreshScope doesn't work with #Configuration, but can I use #PropertySource without #Configuration?
Javadoc :
Annotation providing a convenient and declarative mechanism for adding a PropertySource to Spring's Environment. To be used in conjunction with #Configuration classes.
So, can't i use #RefreshScope without move external properties in application properties and removing #PropertySource and #Configuration annotations from FileProperties class? Do you know if exists a working approach without move the properties?
Thanks

How to load a properties file based on the server environment with spring so that the values can be injected?

To my surprise I have had a difficult time finding an answer to this question. I have Seen many examples where you can use #PropertySource to load a specific properties file for a class. I have also seen examples where you can easily add different property files in spring boot projects. But what I want to do is to do this for a spring project that is NOT spring boot and load a properties file so that the values of this file can be injected in classes annotated with #Component which is dependent on the server environment. So for example if I am on development server I want a particular properties file loaded and on production a different properties file. The reason that I am doing it like this is because my data and service layers are their own modules. These modules contain their own unit tests and can be imported as their own modules in other spring boot projects. I need properties files to be loaded to serve these modules which use spring but not spring boot. I have tried the following, but this does not work.
#Configuration
#Profile("test")
#EnableJpaRepositories("com.hi.repository")
#EnableTransactionManagement
#EnableScheduling
public class InfrastructureConfig {
...
#Bean
public static PropertySourcesPlaceholderConfigurer placeHolderConfigurer() {
PropertySourcesPlaceholderConfigurer configurer = new PropertySourcesPlaceholderConfigurer();
Map<String, String> env = System.getenv();
String propertiesFile=null;
String e = env.get("SERVER_ENV");
if (e.equals("dev")) {
propertiesFile = "environment/development.properties";
} else if (e.equals("prod")) {
propertiesFile = "environment/production.properties";
}
configurer.setLocation(new ClassPathResource(propertiesFile));
return configurer;
}
Then I have a test which looks like this
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(locations = {"classpath:/spring/DealServiceTest-context.xml"})
#ActiveProfiles("test")
public class LogTest {
private static final Logger log = LogManager.getLogger(LogTest.class);
#Autowired
PathsService pathsService;
#Autowired
Environment environment;
#Test
public void testBeans(){
System.out.println("********** WASSUP from LogTest");
System.out.println(environment.getProperty("imageBucket"));
}
Although the test prints out null which indicates to me the properties file has not been loaded and prepared for its values to be injected. How can I achieve this?

You don't really need to set properties yourself, but you can do this using spring configuration. Check the documentation: https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html#boot-features-external-config-profile-specific-properties
If you're using spring boot - all you need to do is create multiple properties file for your environments. And only for properties you need to override.
So your main properties file would be at
src/main/resources/application.properties
Production
src/main/resources/application-prod.properties
Development
src/main/resources/application-dev.properties
Testing
src/main/resources/application-test.properties
And then just use the profile name as your environment variable
java -jar -Dspring.profiles.active=prod demo-0.0.1-SNAPSHOT.jar

Actually, you can just use a placeholder in #PropertySource annotation.
See documentation:
Any ${...} placeholders present in a #PropertySource resource location will be resolved against the set of property sources already registered against the environment.
Assuming that placeholder is present in one of the property sources already registered, e.g. system properties or environment variables, the placeholder will be resolved to the corresponding value.
I've made a simple example, it receives a 'property.environment' value to choose, which .properties file should be used as property source. I have two resource files in my classpath - application-test.properties and application-dev.properties, each one contains a 'test.property' value ('test-env' and 'dev-env' respectively).
Property configuration:
#Configuration
#PropertySource("classpath:/config/application-${property.environment}.properties")
public class PropertyConfig {
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer = new PropertySourcesPlaceholderConfigurer();
return propertySourcesPlaceholderConfigurer;
}
}
Component with #Value
#Component
public class TestService {
#Value("${test.property}")
String testProperty;
#PostConstruct
void init() {
System.out.println("---------------------------------------------------------");
System.out.println("Running in " + testProperty + " environment");
System.out.println("---------------------------------------------------------");
}
}
Build command line example (it runs tests with test environment properties)
mvn clean install -DargLine="-Dproperty.environment=test"
Output
---------------------------------------------------------
Running in test-env environment
---------------------------------------------------------
Run command line example
java -jar -Dproperty.environment=dev PATH_TO_YOUR_JAR.jar
Output
---------------------------------------------------------
Running in dev-env environment
---------------------------------------------------------

Don't hard code based on different environment, in spring boot you can able to maintain properties specific environment easily. Refer https://spapas.github.io/2016/03/31/spring-boot-settings/

I would try to take advantage of the profile mechanism already in place in Spring. You basically have done the job yourself already, the only thing you need to change is to have different configurations for "test" and "production" profiles. I prefer to keep everything related to test away from production code (allowing me to place the TestConfig class below in the test source path), so I would probably do something like this:
#Configuration
#Profile("!test")
#PropertySource(value = "classpath:/environment/production.properties")
#Import(AppConfig.class)
public class ProductionConfig
{
// Your production-specific config goes here
}
#Configuration
#Profile("test")
#PropertySource(value = "classpath:/environment/development.properties")
#Import(AppConfig.class)
public class TestConfig
{
// Your test-specific config goes here
}
#Configuration
public class AppConfig
{
// Needed for spring to handle ${property:default} syntax
#Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigIn() {
return new PropertySourcesPlaceholderConfigurer();
}
}
If you prefer to have one config for both cases, you can let the AppConfig import the TestConfig and the ProductionConfig instead, but that will put test code in to production...
Good luck with your project!

Properties not found with Spring PropertySource

Config
#Configuration
#PropertySources({
#PropertySource("classpath*:properties/test-database.properties")
})
public class DataSourceConfiguration {//...
}
Prop location
D:\Projects\opti\dao\src\main\resources\properties\test-database.properties
D:\Projects\opti\dao\src\main\resources marked as resource folder.

To avoid this kind of problem the issue is to set the jboss.server.config.dir in VM arguments like that :
-Djboss.server.config.dir="[jboss_repository]/server/[default-all-standard-standalone]/conf" –server
and u set PropertySource like this :
#Configuration
#PropertySource("file:${jboss.server.config.dir}/file.properties")
Or you set ur property like that
#PropertySource(value = "classpath:application.properties")
When executed, properties will be imported from the application.properties file, located in the classpath root.

It isn't clear well the your problem considering the details of your question, but a typical problem whit #PropertySource is that yuo have configure a spring bean for manage the properties. In old years in which xml was the best way for configure Spring you used a namespace configuration that configure a spring bean for use proeprties in your bean, mainly with #Value. In java config for benefit of same behaviour you have configure a bean like belove:
#Bean
public static PlaceholderConfigurerSupport propertyPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
I hope that this can help you

How to use spring configuration class in a controller function

I have searched multiple pages thru google. It tells you how to load the configuration thru the annotation. But the tutorial always forget how to use the created object in the controller.
Here is my code.
Properties file (demo.properties)
demo.out_path=c:\demo_dir
Demo Config file (DemoAppConfig.java)
#Configuration
#PropertySource("classpath:demo.properties")
public class DemoAppConfig {
#Value("${demo.out_path}")
private String OutPath;
#Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigInDev() {
return new PropertySourcesPlaceholderConfigurer();
}
}
Servlet config (demo-servlet.xml)
<!-- Properties -->
<context:property-placeholder location="classpath:demo.properties" ignore-unresolvable="true" />
How do I call the properties inside a controller? I tried auto wire annotation of DemoAppConfig as a property but it fails. I tried instantiating the DemoAppConfig as a new class but all property were not loaded.
Note: Used spring version 4.1.7.RELEASE

I know one way is to configure system property look up in xml config as below:
<util:properties id="systemPropertyLookup" location="classpath:demo.properties"/>
Of course, you need to add in spring-util schema declaration:
<beans ....
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="....
http://www.springframework.org/schema/util/spring-util.xsd">
Then inject your property value into your controller as follow:
#Value("#{systemPropertyLookup['demo.out_path']")
private String OutPath;

Checking my project, this is how I have been loading persistence.properties and I have been able to use #Value just like you have configured:
#Configuration
#ComponentScan(basePackageClasses = Application.class)
class ApplicationConfig {
#Bean
public static PropertySourcesPlaceholderConfigurer propertyPlaceholderConfigurer() {
PropertySourcesPlaceholderConfigurer ppc = new PropertySourcesPlaceholderConfigurer();
ppc.setLocation(new ClassPathResource("/persistence.properties"));
return ppc;
}
}
Make sure that it is on the classpath and that the compiler copies the resource file into the distributable.