Spring Boot @ConfigurationProperties not retrieving properties from Environment

Question

I'm using Spring Boot 1.2.1 and trying to create a @ConfigurationProperties bean with validation like so:

package com.sampleapp;

import java.net.URL;

import javax.validation.constraints.NotNull;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties
public class SampleAppProperties {
    @NotNull
    private URL url;

    public URL getUrl() {
        return url;
    }
}

The class to bootstrap the application is:

package com.sampleapp;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.Environment;

@SpringBootApplication
@EnableConfigurationProperties
public class SampleApplication implements EnvironmentAware {
    private static Logger LOGGER = LoggerFactory.getLogger(SampleApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(SampleApplication.class, args);
    }

    @Override
    public void setEnvironment(Environment environment) {
        LOGGER.info("URL = {}", environment.getRequiredProperty("url"));
    }
}

When I try and start this application I receive the following exception stack:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sampleAppProperties': Could not bind properties to [unknown] (target=, ignoreInvalidFields=false, ignoreUnknownFields=true, ignoreNestedProperties=false); nested exception is org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'target' on field 'url': rejected value [null]; codes [NotNull.target.url,NotNull.url,NotNull.java.net.URL,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [target.url,url]; arguments []; default message [url]]; default message [may not be null]
    at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.postProcessBeforeInitialization(ConfigurationPropertiesBindingPostProcessor.java:303)
    at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.postProcessBeforeInitialization(ConfigurationPropertiesBindingPostProcessor.java:250)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:408)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1558)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:762)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
    at com.sampleapp.SampleApplication.main(SampleApplication.java:17)
Caused by: org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'target' on field 'url': rejected value [null]; codes [NotNull.target.url,NotNull.url,NotNull.java.net.URL,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [target.url,url]; arguments []; default message [url]]; default message [may not be null]
    at org.springframework.boot.bind.PropertiesConfigurationFactory.validate(PropertiesConfigurationFactory.java:294)
    at org.springframework.boot.bind.PropertiesConfigurationFactory.doBindPropertiesToTarget(PropertiesConfigurationFactory.java:253)
    at org.springframework.boot.bind.PropertiesConfigurationFactory.bindPropertiesToTarget(PropertiesConfigurationFactory.java:225)
    at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.postProcessBeforeInitialization(ConfigurationPropertiesBindingPostProcessor.java:296)
    ... 17 common frames omitted

As you can see in the setEnvironment method above I'm logging the url property to validate that it's part of the Environment and it is displayed before the exception:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.2.1.RELEASE)

2015-02-12 12:32:01.384  INFO 5608 --- [           main] c.s.SampleApplication                    : Starting SampleApplication on VDDK03E-14FB6E5 with PID 5608 (D:\projects\onboarding-parser\target\classes started by .....
2015-02-12 12:32:01.509  INFO 5608 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@3252ac20: startup date [Thu Feb 12 12:32:01 EST 2015]; root of context hierarchy
2015-02-12 12:32:03.040  INFO 5608 --- [           main] c.s.SampleApplication                    : URL = http://www.joe.com
2015-02-12 12:32:03.378 ERROR 5608 --- [           main] o.s.b.b.PropertiesConfigurationFactory   : Properties configuration failed validation
2015-02-12 12:32:03.378 ERROR 5608 --- [           main] o.s.b.b.PropertiesConfigurationFactory   : Field error in object 'target' on field 'url': rejected value [null]; codes [NotNull.target.url,NotNull.url,NotNull.java.net.URL,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [target.url,url]; arguments []; default message [url]]; default message [may not be null]
2015-02-12 12:32:03.394  WARN 5608 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt

The url property is pulled from the application.properties file in src/main/resources. The contents of the file are:

url=http://www.joe.com

Answer 1

There's no setter in your bean. Add a setter.