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SpringBoot application doesn't autowire field

I do have ServiceImpl which looks like this:
#Service
#RequiredArgsConstructor
public class ServiceAImpl implements ServiceA {
private final String fieldA;
#Override
public boolean isFieldA(String text){
return fieldA.equals(text);
}
And I would like to inject a field value to fieldA in an Application.java from application.yml like this:
#EnableSwagger2
#SpringBootApplication
public class Application {
#Value("${fieldA}")
private String fieldA;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public ServiceA serviceA() {
return new ServiceAImpl(fieldA);
}
But I receive the following error when running SpringBoot app:
Error creating bean with name 'serviceAImpl' defined in URLNo qualifying bean of type 'java.lang.String' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
Do you have any solution for that?

You annotated your class with #Service and defined it manually as a bean with the #Bean annotation. I do think the second is the way you planned to use it.
The #Service annotation will make this class get picked up by Spring's component scan and additionally create an instance of it.
Of course it tries to resolve the parameters and fails when it tries to find a matching "bean" for the String field because there is no simple String bean (and should not :) ).
Remove the #Service annotation and everything should work as expected.

Try this
#Service
public class ServiceAImpl implements ServiceA {
private final String fieldA;
#Autowire
public ServiceAImpl(#Value("${fieldA}") String fieldA){
this.fieldA = fieldA;
}
#Override
public boolean isFieldA(String text){
return fieldA.equals(text);
}
}
and this
#EnableSwagger2
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
You should not use #Service and #Bean for the same class!

Spring is not so smart :)
You should annotate your bean like:
#RequiredArgsConstructor
public class ServiceAImpl {
#Value("${fieldA}")
private final String something;
...
But I'm not sure it will work with the #RequiredFieldsConstructor, it would be simpler for you write down the constructor annotated with #Autowired and using the #Value annotation for the String parameter:
#Autowired
public ServiceAImpl(#Value("${aProp}") String string) {

You're using two bean declaration mechanisms:
You're registering your bean using #Service
You're registering a bean using #Bean
This means that your service will be created twice. The one defined using #Bean works properly, since it uses the #Value annotation to inject the proper value in your service.
However, the service created due to #Service doesn't know about the #Value annotation and will try to find any bean of type String, which it can't find, and thus it will throw the exception you're seeing.
Now, the solution is to pick either one of these. If you want to keep the #Bean configuration, you should remove the #Service annotation from ServiceAImpl and that will do the trick.
Alternatively, if you want to keep the #Service annotation, you should remove the #Bean declaration, and you should write your own constructor rather than relying on Lombok because this allows you to use the #Value annotation within the constructor:
#Service
public class ServiceAImpl implements ServiceA {
private final String fieldA;
/**
* This constructor works as well
*/
public ServiceAImpl(#Value("${fieldA}") String fieldA) {
this.fieldA = fieldA;
}
#Override
public boolean isFieldA(String text){
return fieldA.equals(text);
}
}

If you want to declare ServiceAImpl as a Spring bean in your Java Configuration file, you should remove the #Service annotation from the class declaration. These annotations doesn't work well together.
ServiceAImpl.java
import org.springframework.beans.factory.annotation.Autowired;
public class ServiceAImpl implements ServiceA {
private final String fieldA;
#Autowired
public ServiceAImpl(String fieldA) {
this.fieldA = fieldA;
}
#Override
public boolean isFieldA(String text) {
return fieldA.equals(text);
}
}
Application.java
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
#SpringBootApplication
public class Application {
#Value("${fieldA}")
private String fieldA;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public ServiceA serviceA() {
return new ServiceAImpl(fieldA);
}
}
Your application.properties
fieldA=value

The below implementation works well for me. You have two issues, first you have to choose between #Service and #Bean and the other issue I've seen in your code was the #Value annotation, you have to use only to inject a value from the properties.
#SpringBootApplication
public class TestedValueApplication {
#Autowired
void printServiceInstance(ServiceA service) {
System.out.println("Service instance: " + service);
System.out.println("value==value? " + service.isFieldA("value"));
}
public static void main(String[] args) {
SpringApplication.run(TestedValueApplication.class, args);
}
#Bean
public ServiceA serviceA(#Value("${fieldA}") String fieldA) {
return new ServiceAImpl(fieldA);
}
}
Service:
public class ServiceAImpl implements ServiceA {
private String fieldA;
ServiceAImpl(String fieldA) {
this.fieldA = fieldA;
}
public boolean isFieldA(String text) {
return fieldA.equals(text);
}
}
application.properties:
fieldA=value

Initializa Bean with YAML configuration in Spring Boot

I would like to read some properties, like DB access configs, when initializing bean or service in spring boot.
Anyone knows good ways ?
This is my current code snippet.
public class SampleApplication implements ApplicationRunner
{
#Autowired
private YAMLConfig myConfig;
#Override
public void run(ApplicationArguments args) throws Exception
{
System.out.println(myConfig != null); //YAMLConfig has been intialized here
}
public SampleApplication()
{
System.out.println(myConfig == null); //myConfig is null
}
#Configuration
public static class Config
{
#Bean
#ConditionalOnProperty(value = {"batch.execute"}, havingValue = "SampleApplication")
public SampleApplication sampleApplication()
{
return new SampleApplication();
}
}
}
#Configuration
#EnableConfigurationProperties
#ConfigurationProperties
public class YAMLConfig
{
private String environment;
public String getEnvironment()
{
return environment;
}
public void setEnvironment(String environment)
{
this.environment = environment;
}
}
Thanks for taking a look at this!

create this method inside your SampleApplication class
#PostConstruct
public void init() {
// at this point, all the dependency injection has happened already
myConfig.doStuff()
}
it will be called by spring automatically after all bean initialization has been done.

Spring-Boot multi module project load property-file

I have a Spring-Boot-Application as a multimodule-Project in maven. The structure is as follows:
Parent-Project
|--MainApplication
|--Module1
|--ModuleN
In the MainApplication project there is the main() method class annotated with #SpringBootApplication and so on. This project has, as always, an application.properties file which is loaded automatically. So I can access the values with the #Value annotation
#Value("${myapp.api-key}")
private String apiKey;
Within my Module1 I want to use a properties file as well (called module1.properties), where the modules configuration is stored. This File will only be accessed and used in the module. But I cannot get it loaded. I tried it with #Configuration and #PropertySource but no luck.
#Configuration
#PropertySource(value = "classpath:module1.properties")
public class ConfigClass {
How can I load a properties file with Spring-Boot and access the values easily? Could not find a valid solution.
My Configuration
#Configuration
#PropertySource(value = "classpath:tmdb.properties")
public class TMDbConfig {
#Value("${moviedb.tmdb.api-key}")
private String apiKey;
public String getApiKey() {
return apiKey;
}
#Bean
public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
return new PropertySourcesPlaceholderConfigurer();
}
}
Calling the Config
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
public TMDbWarper(){
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
I'm getting an NullPointerException in the constructor when I autowire the warper.

For field injection:
Fields are injected right after construction of a bean, before any config methods are invoked. Such a config field does not have to be public. Refer Autowired annotation for complete usage. Use constructor injection in this case like below:
#Component
public class TMDbWarper {
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
#Autowired
public TMDbWarper(final TMDbConfig tmdbConfig){
this.tmdbConfig = tmdbConfig;
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
(or)
Use #PostConstruct to initialise like below:
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
#PostConstruct
public void init() {
// any initialisation method
tmdbConfig.getConfig();
}

Autowiring is performed just after the creation of the object(after calling the constructor via reflection). So NullPointerException is expected in your constructor as tmdbConfig field would be null during invocation of constructor
You may fix this by using the #PostConstruct callback method as shown below:
#Component
public class TMDbWarper {
#Autowired
private TMDbConfig tmdbConfig;
private TmdbApi tmdbApi;
public TMDbWarper() {
}
#PostConstruct
public void init() {
tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}
public TmdbApi getTmdbApi() {
return this.tmdbApi;
}
}
Rest of your configuration seems correct to me.
Hope this helps.

Here is a Spring Boot multi-module example where you can get properties in different module.
Let's say I have main application module, dataparse-module, datasave-module.
StartApp.java in application module:
#SpringBootApplication
public class StartApp {
public static void main(String[] args) {
SpringApplication.run(StartApp.class, args);
}
}
Configuration in dataparse-module. ParseConfig.java:
#Configuration
public class ParseConfig {
#Bean
public XmlParseService xmlParseService() {
return new XmlParseService();
}
}
XmlParseService.java:
#Service
public class XmlParseService {...}
Configuration in datasave-module. SaveConfig.java:
#Configuration
#EnableConfigurationProperties(ServiceProperties.class)
#Import(ParseConfig.class)//get beans from dataparse-module - in this case XmlParseService
public class SaveConfig {
#Bean
public SaveXmlService saveXmlService() {
return new SaveXmlService();
}
}
ServiceProperties.java:
#ConfigurationProperties("datasave")
public class ServiceProperties {
private String message;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
application.properties in datasave-module in resource/config folder:
datasave.message=Multi-module Maven project!
threads.xml.number=5
file.location.on.disk=D:\temp\registry
Then in datasave-module you can use all your properties either through #Value.
SaveXmlService.java:
#Service
public class SaveXmlService {
#Autowired
XmlParseService xmlParseService;
#Value("${file.location.on.disk: none}")
private String fileLocation;
#Value("${threads.xml.number: 3}")
private int numberOfXmlThreads;
...
}
Or through ServiceProperties:
Service.java:
#Component
public class Service {
#Autowired
ServiceProperties serviceProperties;
public String message() {
return serviceProperties.getMessage();
}
}

I had this situation before, I noticed that the properties file was not copied to the jar.
I made the following to get it working:
In the resources folder, I have created a unique package, then stored my application.properties file inside it. e.g: com/company/project
In the configuration file e.g: TMDBConfig.java I have referenced the full path of my .properties file:
#Configuration
#PropertySource("classpath:/com/company/project/application.properties")
public class AwsConfig
Build and run, it will work like magic.

You could autowire and use the Enviornment bean to read the property
#Configuration
#PropertySource(value = "classpath:tmdb.properties")
public class TMDbConfig {
#Autowired
private Environment env;
public String getApiKey() {
return env.getRequiredProperty("moviedb.tmdb.api-key");
}
}
This should guarantee that property is read from the context when you invoke the getApiKey() method regardless of when the #Value expression is resolved by PropertySourcesPlaceholderConfigurer.

resolving #Value fails when invoked from external class - spring java

In the property file (config.properties) I defined several properties:
my.property.first=xyz
my.property.second=12
I created a class to read these properties:
package my.package.first;
............
#Configuration
public Class MyProperties {
#Value("${my.property.first}") private String propertyFirst;
#Value ("${my.property.second}") private String propertySecond;
public String getPropertyFirst() {
return propertyFirst;
}
public int getPropertySecond() {
return propertySecond
}
#Bean
public MyProperties getInstance() {
return this;
}
}
Now I want to use these properties in a class placed in some other package:
package my.otherpackage.third;
import my.property.package.first.MyProperties;
.............................
public class GetMyProperties{
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyProperties.class);
MyProperties myProperties =context.getBean("getInstance",MyProperties.class);
//This returns ${my.property.first}
String propertyFirst = myProperties.getPropertyFirst();
// This returns ${my.property.second}
int propertySecond = context.getBeanFactory().resolveEmbeddedValue(("${my.property.first}"));
}
I try to solve this by using only Annotations.
I use Spring 4.
Thanks

MyProperties isn't really a #Configuration class, it is a bean. Give it the annotation #Component and move the #Bean declaration to another #Configuration class. It doesn't matter where the bean is defined for spring (as long as it is in a configuration class), it'll pick it up if you have the #ComponentScan or #SpringBootApplication somewhere in your app, which I'm pretty sure you do. your MyProperties class you make #Component
You'll want:
#Component
public class MyProperties {
#Value("${my.property.first}") private String propertyFirst;
#Value ("${my.property.second}") private String propertySecond;
public String getPropertyFirst() {
return propertyFirst;
}
public void setPropertyFirst(String propertyFirst){
this.propertyFirst = propertyFirst;
}
public int getPropertySecond() {
return propertySecond
}
public void setPropertySecond(String propertySecond){
this.propertySecond= propertySecond;
}
}
#Configuration
public class Config {
#Bean
public MyProperties getInstance() {
return new MyProperties();
}
}
package my.otherpackage.third;
import my.property.package.first.MyProperties;
.....
#EnableAutoConfiguration
#ComponentScan(basePackages = {"my"})
public class GetMyProperties{
public static void main(String[] args){
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(GetMyProperties.class);
MyProperties myProperties =context.getBean("getInstance",MyProperties.class);
//This returns the value of ${my.property.first}
String propertyFirst = myProperties.getPropertyFirst();
// This returns the value of ${my.property.second}
int propertySecond = myProperties.getPropertySecond();
}
}

How to enable #ConditionalOnProperty in spring-boot on runtime changeable property

I have two class which depends on config variable:
#Component
#ConditionalOnProperty("config.db")
public class DatabaseTokenStore implements TokenStore {
}
#Component
#ConditionalOnMissingBean(DatabaseTokenStore.class)
public class SimpleTokenStore implements TokenStore {
}
so when db is true then DatabaseTokenStore class is autowired when false then SimpleTokenStore is autowired. Problem is that I can change this property in runtime with CRaSH. Then this mechanic will not work. Is there some way how to change implement of interface in runtime ?

Initialize both TokenStores on startup. And create a resolver to inject into classes where you need to work with them. Like so:
#Component
public class HelloStoreResolver {
#Autowired
private HelloStore oneHelloStore;
#Autowired
private HelloStore twoHelloStore;
public HelloStore get() {
if (condition) {
return oneHelloStore;
} else {
return twoHelloStore;
}
}
}
#Component
public class HelloController {
#Autowired
private HelloStoreResolver helloResolver;
//annotations omitted
public String sayHello() {
return helloResolver.get().hello();
}
}