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Spring create generic service multiple times using generic in constructor

I have a service that uses some object as a generic
#Component
#RequiredArgsConstructor
public class SomeGenericService<T extends Base> {
private final T base;
public void someWork(String info) {
base.someAction(info);
}
}
I also have 3 Base implementations marked with #Component(Base1, Base2, Base3)
I want spring itself to create a service with the generic it needs, for the following example
#Component
#RequiredArgsConstructor
public class Runner implements CommandLineRunner {
private final SomeGenericService<Base1> s1;
private final SomeGenericService<Base2> s2;
private final SomeGenericService<Base3> s3;
#Override
public void run(String... args) throws Exception {
String someString = "text";
s1.someWork(someString);
s2.someWork(someString);
s3.someWork(someString);
}
}
But after the launch, the spring does not understand what I want from it.
Parameter 0 of constructor in SomeGenericService required a single bean, but 3 were found:
- base1: defined in file [Base1.class]
- base2: defined in file [Base2.class]
- base3: defined in file [Base3.class]
Is it possible to set this to automatic, without manually configuring it via the #Bean annotation for each service?

You need to define how those beans should be injected. It's a good practice to have some #Configurations for this purpose. Something like:
#Configuration
#Import({
Base1.class,
Base2.class,
Base3.class
})
public class SomeConfig {
#Bean
SomeGenericService<Base1> someGenericService1() {
return new SomeGenericService(new Base1());
}
#Bean
SomeGenericService<Base2> someGenericService2() {
return new SomeGenericService(new Base2());
}
#Bean
SomeGenericService<Base3> someGenericService3() {
return new SomeGenericService(new Base3());
}
}

Testing using spring boot throws null pointer exception

I am new to spring boot and i am trying to test a very simple class. But when i run the testMe() below I get exception below
java.lang.NullPointerException
at MyTest.testMe(MyTest.java:25)
at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
My understanding is when the context is loaded all the beans are initialized and object HelloWorld is created and are autowired in MyTest call. But helloWorld object is null at line helloWorld.printHelloWorld();
I need assistance here to understand what is missing.
#RunWith(MockitoJUnitRunner.class)
#SpringBootTest(classes = {AppConfigTest.class})
public class MyTest {
#Mock
#Autowired
private Message myMessage;
#Autowired
private HelloWorld helloWorld;
#Test
public void testMe(){
helloWorld.printHelloWorld();
}
}
#Configuration
public class AppConfigTest {
#Bean
public HelloWorld helloWorld() {
return new HelloWorldImpl();
}
#Bean
public Message getMessage(){
return new Message("Hello");
}
}
public interface HelloWorld {
void printHelloWorld();
}
public class HelloWorldImpl implements HelloWorld {
#Autowired
Message myMessage;
#Override
public void printHelloWorld() {
System.out.println("Hello : " + myMessage.msg);
}
}
public class Message {
String msg;
Message(String message){
this.msg = message;
}
}

You're running your tests with a runner that's not Spring-aware, so no wiring is happening. Look at the Spring Boot testing documentation, all their examples use #RunWith(SpringRunner.class). To mock a bean, annotate it with #MockBean, not #Mock. Make sure that the spring-boot-starter-test is included in your POM.

Injecting a service in a springboot aws lambda

I'm building a lambda based on this code
The uppercaseService is "injected" like this:
#Component("uppercaseFunction")
public class UppercaseFunction implements Function<UppercaseRequest, UppercaseResponse> {
private final UppercaseService uppercaseService;
public UppercaseFunction(final UppercaseService uppercaseService) {
this.uppercaseService = uppercaseService;
}
This works fine until I try to inject another service inside UppercaseService.
#Service
public class UppercaseService {
#Autowired
MyService myService;
public String uppercase(final String input) {
myService.doSomething();
return input.toUpperCase(Locale.ENGLISH);
}
}
AWS console returns:
"errorMessage": "Error creating bean with name 'uppercaseService':
Unsatisfied dependency expressed through field 'myService'
This service works in a non lambda context. The class is present in the .jar built with maven package.
I tried the solution # https://www.profit4cloud.nl/blog/just-spring-enabled-aws-lambdas without success.

You have to initialize your MyService bean first. Since your MyService come from external service which very likely to have different package than your own package
Either directly:
#SpringBootApplication
public class UpperFunctionApplication {
#Bean
public MyService myService() {
return new MyService(); // You must provide code to construct new MyService bean
}
public static void main(String[] args) throws Exception {
SpringApplication.run(UpperFunctionApplication.class, args);
}
}
or via componentscan:
#SpringBootApplication(scanBasePackageClasses = {UpperFunctionApplication.class, MyService.class})
public class UpperFunctionApplication {
#Bean
public MyService myService() {
return new MyService(); // You must provide code to construct new MyService bean
}
public static void main(String[] args) throws Exception {
SpringApplication.run(UpperFunctionApplication.class, args);
}
}

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.

SpringApplication not able to instantiate bean

I am new to Spring & WebService and trying a few guides on Spring.io.
I planned to create a basic RESTful WebService which consumes Google Direction API and returns just the status.
Here are the classes:
Resource
#JsonIgnoreProperties(ignoreUnknown=true)
public class Direction {
// getters & setters
public Direction() {
super();
}
private String status;
public String toString() {
return status;
}
}
Controller
#Controller
public class Consumer {
public Consumer() {
super();
}
#Resource
private String url;
#Resource
private RestTemplate client;
#Resource
private String apiKey;
#RequestMapping(value = "/directions", method=RequestMethod.GET)
public #ResponseBody Direction consume(#RequestParam(value="source") String source, #RequestParam(value="destination") String destination) {
return consumeDirections(buildURI(source, destination));
}
// Builds URI
private String buildURI(...) {
...
}
private Direction consumeDirections(final String requestURI) {
return client.getForObject(requestURI, Direction.class);
}
}
Configuration v1
#Configuration
#ComponentScan
#EnableAutoConfiguration
public class Application {
public static void main(String[] args) {
SpringApplication.run(Consumer.class, args);
}
}
Springconfig
http://pastebin.com/dsNVBWQq
Spring returns that No qualifying bean of type [java.lang.String] found for dependency.
This happens for all the beans in Consumer.
However, this works Configuration v2
#Configuration
#ComponentScan
#EnableAutoConfiguration
public class Application {
#Resource
private Consumer consumer;
public void execute() {
System.out.println(consumer.consume("x", "z"));
}
public static void main(String[] args) {
ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("application-config.xml");
context.getBean(Application.class).execute();
}
}
Some observations
#Resouce(Explicitly define bean) doesnt work for v1
SpringApplication is not aware of the Springconfig and fails during bean instantiation
I would like to understand why this issue crops up and how to resolve it?

The reason is very easy, the xml config is not loaded. have a look at Spring-Boot: XML Config
if you don't wanna touch existing xml, you need another #configuration annotated class and #ImportResource to load the xml configuration, just like the document says.
IMO, you don't need apiKey and url in the config, you should annotate them with #value, and define them in a .properties file. There are also default settings of spring boot, you get take advantage of it. like, name the properities application.properities and put it on classpath, spring boot will load it automatically.