Unable to read configurationProperties - spring

Question

I am trying to use ConfiguartionProperties to read properties from application.prop files. But I am getting NullPointerException because at the time of initiating the bean the properties are not read properly from application.prop file.
#Configuration
#ConfigurationProperties(prefix = "httpool")
public class ClientHttpPoolConfig {
private Integer maxPerRoute;
private Integer maxTotal;
private Integer connectionRequestTimeout;
private Integer connectTimeout;
private Integer socketTimeout;
#Bean
public PoolingHttpClientConnectionManager poolingHttpClntConnMger() {
PoolingHttpClientConnectionManager result = new PoolingHttpClientConnectionManager();
result.setDefaultMaxPerRoute(maxPerRoute); // maxPerRoute is null.
result.setMaxTotal(maxTotal);
return result;
}
}

Answer 1

I simplified as much as I could, so I'm using very simple bean:
StringWrapper
package betlista.springTests.beanInConfiguration;
/** Represents a very simple Bean */
public class StringWrapper {
private String name;
public StringWrapper(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
There is nothing special in configuration class too...
Config
package betlista.springTests.beanInConfiguration;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
#Component
#ConfigurationProperties
public class Config {
String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Bean
public StringWrapper getStringWrapper() {
return new StringWrapper(name);
}
}
and finally application
package betlista.springTests.beanInConfiguration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class SpringBootConsoleApplication implements CommandLineRunner {
private static Logger LOG = LoggerFactory.getLogger(SpringBootConsoleApplication.class);
#Autowired
StringWrapper stringWrapper;
public static void main(String[] args) {
SpringApplication.run(SpringBootConsoleApplication.class, args);
}
#Override
public void run(String... args) {
LOG.info("stringWrapper.name: {}", stringWrapper.getName());
}
}
Just for completeness
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>betlista</groupId>
<artifactId>springTests-beanInConfiguration</artifactId>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.2.5.RELEASE</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-test -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<version>2.2.5.RELEASE</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
Prefix
Pretty much same works with #ConfigurationProperties("my") and my.name=Betlista in property file.
All available in GitHub: https://github.com/Betlista/SpringTests/tree/master/BeanInConfiguration

Answer 2

in your application.properties files, parameters should be as follow:
httpool.max-per-route=//here your Integer value
httpool.max-total=//here your Integer value
httpool.connection-requestTimeout=//here your Integer value
httpool.connect-timeout=//here your Integer value
httpool.socket-timeout=//here your Integer value
EDITED:
and you must write this annotation to your Main class
#EnableConfigurationProperties({
ClientHttpPoolConfig.class
})