#Component
public class car {
void getCar(){
System.out.println("Honda");
}
}
public class Tyre {
#Autowired
private car cars;
#Test
void print(){
cars.getCar();
}
}
java.lang.NullPointerException when "cars.getcar" is called
Spring Version 2.7.1
I am trying to annotate an autowire for Car.class
but it returns null on run time
Attached the project Structure
add #SpringBootTest on top of the test class.
#SpringBootTest
public class Tyre {
#Autowired
private car cars;
#Test
void print(){
cars.getCar();
}
Related
I use spring boot 3
I created a object manually, FormGenerator, because everytime I use is in my advance search, some field need to be reset.
So I think the scope prototype is ok for that
#Repository
public class SchoolRepositoryCustomImpl extends SimpleJpaRepository<School, Long> implements SchoolRepositoryCustom {
#Override
public List<School> advanceSearch(SchoolSearch search) {
FormGenerator qg = new FormGenerator();
}
...
}
#Scope("prototype")
public class FormGenerator {
private int fieldCounter=0;
#Autowired
private EntityManager entityManager;
...
}
When I run application, entityManager is null?
It is null because you created the object manually by calling the constructor. You need to obtain it from the ApplicationContext. Something like this:
#Repository
public class SchoolRepositoryCustomImpl extends SimpleJpaRepository<School, Long> implements SchoolRepositoryCustom {
#Autowired
private ApplicationContext applicationContext;
#Override
public List<School> advanceSearch(SchoolSearch search) {
FormGenerator qg = applicationContext.getBean(FormGenerator.class);
}
...
}
I have a dummy project where I try figure out how to test pointcuts being triggered.
My project consists of 1 aspect bean which just prints after a foo method is called
#Component
#Aspect
public class SystemArchitecture {
#After("execution(* foo(..))")
public void after() {
System.out.println("#After");
}
}
And a FooServiceImpl with implemented foo method
#Service
public class FooServiceImpl implements FooService{
#Override
public FooDto foo(String msg) {
return new FooDto(msg);
}
}
The code works and and I can see "#After" being printed to console, but I can't check programatically if after pointcut was called using the test below.
#SpringBootTest
public class AspectTest {
#Autowired
private FooService fooService;
#Test
void shouldPass() {
fooService.foo("hello");
}
}
I've also tried using non-bean proxy as was adviced in https://stackoverflow.com/a/56312984/18224588, but this time I'm getting an obvious error cannot extend concrete aspect because my spy proxy is no longer viewed as an aspect:
public class AspectNoContextTest {
#Test
void shouldPass() {
FooService fooService = Mockito.mock(FooService.class);
SystemArchitecture systemArchitecture = Mockito.spy(new SystemArchitecture());
AspectJProxyFactory aspectJProxyFactory = new AspectJProxyFactory(fooService);
aspectJProxyFactory.addAspect(systemArchitecture);
DefaultAopProxyFactory proxyFactory = new DefaultAopProxyFactory();
AopProxy aopProxy = proxyFactory.createAopProxy(aspectJProxyFactory);
FooService proxy = (FooService) aopProxy.getProxy();
proxy.foo("foo");
verify(systemArchitecture, times(1)).after();
}
}
Ok, after some digging, I found that it's possible to accomplish this by making an aspect a #SpyBean. Also AopUtils can be used for performing additional checks
#SpringBootTest
public class AspectTest {
#Autowired
private FooService fooService;
#SpyBean
private SystemArchitecture systemArchitecture;
#Test
void shouldPass() {
assertTrue(AopUtils.isAopProxy(fooService));
assertTrue(AopUtils.isCglibProxy(fooService));
fooService.foo("foo");
verify(systemArchitecture, times(1)).after();
}
}
I'm trying to learn mockito by testing a service layer, but
CarServiceTest.java
#RunWith(MockitoJUnitRunner.class)
#ContextConfiguration(classes = {CarService.class})
public class CarServiceTest {
#InjectMocks
private CarService carService;
#Mock
private CarRepository carRepository;
#Test
public void getCarDetails_returnsCarInfo() {
//Mockito.when **** is not able to mock, not sure why.
Mockito.when(this.carRepository.findByName("prius")).thenReturn(new Car("prius","hybrid"));
Car expected = new Car("prius", "hybrid");
//Car expected = carService.getCarDetails("prius");
Assertions.assertThat(expected.getName()).isEqualTo("prius");
Assertions.assertThat(expected.getType()).isEqualTo("hybrid");
}
CarService.java
#Service
public class CarService {
#Autowired
CarRepository carRepository;
public Car getCarDetails(String name) {
Car car = carRepository.findByName(name);
if (car == null) {
throw new CarNotFoundException();
}
System.out.println(car.getName());
return car;
}
CarRepository.java
#Repository
public class CarRepository {
public Car findByName(String name) {
if (name.equals("prius")){
Car car = new Car("prius", "hybrid");
return car;
} else {
throw new CarNotFoundException();
}
}
#InjectMocks won't inject into #Autowired fields. Change CarService to constructor injection.
Turned out was importing org.junit.jupiter.api.Test, I changed to org.junit.Test and it worked fine.
In normal Spring, when we want to autowire an interface, we define it's implementation in Spring context file.
What about Spring boot?
how can we achieve this?
currently we only autowire classes that are not interfaces.
Another part of this question is about using a class in a Junit class inside a Spring boot project.
If we want to use a CalendarUtil for example, if we autowire CalendarUtil, it will throw a null pointer exception. What can we do in this case? I just initialized using "new" for now...
Use #Qualifier annotation is used to differentiate beans of the same interface
Take look at Spring Boot documentation
Also, to inject all beans of the same interface, just autowire List of interface
(The same way in Spring / Spring Boot / SpringBootTest)
Example below:
#SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
public interface MyService {
void doWork();
}
#Service
#Qualifier("firstService")
public static class FirstServiceImpl implements MyService {
#Override
public void doWork() {
System.out.println("firstService work");
}
}
#Service
#Qualifier("secondService")
public static class SecondServiceImpl implements MyService {
#Override
public void doWork() {
System.out.println("secondService work");
}
}
#Component
public static class FirstManager {
private final MyService myService;
#Autowired // inject FirstServiceImpl
public FirstManager(#Qualifier("firstService") MyService myService) {
this.myService = myService;
}
#PostConstruct
public void startWork() {
System.out.println("firstManager start work");
myService.doWork();
}
}
#Component
public static class SecondManager {
private final List<MyService> myServices;
#Autowired // inject MyService all implementations
public SecondManager(List<MyService> myServices) {
this.myServices = myServices;
}
#PostConstruct
public void startWork() {
System.out.println("secondManager start work");
myServices.forEach(MyService::doWork);
}
}
}
For the second part of your question, take look at this useful answers first / second
You can also make it work by giving it the name of the implementation.
Eg:
#Autowired
MyService firstService;
#Autowired
MyService secondService;
Assume that you have a GreetingService
public interface GreetingService {
void doGreetings();
}
And you have 2 implementations HelloService
#Service
#Slf4j
public class HelloService implements GreetingService{
#Override
public void doGreetings() {
log.info("Hello world!");
}
}
and HiService
#Slf4j
#Service
public class HiService implements GreetingService{
#Override
public void doGreetings() {
log.info("Hi world!");
}
}
Then you have another interface, which is BusinessService to call some business
public interface BusinessService {
void doGreetings();
}
There are some ways to do that
#1. Use #Autowired
#Component
public class BusinessServiceImpl implements BusinessService{
#Autowired
private GreetingService hiService; // Spring automatically maps the name for you, if you don't want to change it.
#Autowired
private GreetingService helloService;
#Override
public void doGreetings() {
hiService.doGreetings();
helloService.doGreetings();
}
}
In case you need to change your implementation bean name, refer to other answers, by setting the name to your bean, for example #Service("myCustomName") and applying #Qualifier("myCustomName")
#2. You can also use constructor injection
#Component
public class BusinessServiceImpl implements BusinessService {
private final GreetingService hiService;
private final GreetingService helloService;
public BusinessServiceImpl(GreetingService hiService, GreetingService helloService) {
this.hiService = hiService;
this.helloService = helloService;
}
#Override
public void doGreetings() {
hiService.doGreetings();
helloService.doGreetings();
}
}
This can be
public BusinessServiceImpl(#Qualifier("hiService") GreetingService hiService, #Qualifier("helloService") GreetingService helloService)
But I am using Spring Boot 2.6.5 and
public BusinessServiceImpl(GreetingService hiService, GreetingService helloService)
is working fine, since Spring automatically get the names for us.
#3. You can also use Map for this
#Component
#RequiredArgsConstructor
public class BusinessServiceImpl implements BusinessService {
private final Map<String, GreetingService> servicesMap; // Spring automatically get the bean name as key
#Override
public void doGreetings() {
servicesMap.get("hiService").doGreetings();
servicesMap.get("helloService").doGreetings();
}
}
List also works fine if you run all the services. But there is a case that you want to get some specific implementation, you need to define a name for it or something like that. My reference is here
For this one, I use #RequiredArgsConstructor from Lombok.
As mentioned in the comments, by using the #Qualifier annotation, you can distinguish different implementations as described in the docs.
For testing, you can use also do the same. For example:
#RunWith(SpringRunner.class)
#SpringBootTest
public class MyClassTests {
#Autowired
private MyClass testClass;
#MockBean
#Qualifier("default")
private MyImplementation defaultImpl;
#Test
public void givenMultipleImpl_whenAutowiring_thenReturnDefaultImpl() {
// your test here....
}
}
There are 2 approaches when we have autowiring of an interface with multiple implementations:
Spring #Primary annotation
In short it tells to our Spring application whenever we try to autowire our interface to use that specific implementation which is marked with the #Primary annotation. It is like a default autowiring setting. It can be used only once per cluster of implementations of an interface. → #Primary Docs
Spring #Qualifier annotation
This Spring annotation is giving us more control to select the exact implementation wherever we define a reference to our interface choosing among its options. → #Qualifier Docs
For more details follow the links to their documentation.
public interface SomeInterfaces {
void send(String message);
String getType();
}
kafka-service
#Component
public class SomeInterfacesKafkaImpl implements SomeInterfaces {
private final String type = "kafka";
#Override
public void send(String message) {
System.out.println(message + "through Kafka");
}
#Override
public String getType() {
return this.type;
}
}
redis-service
#Component
public class SomeInterfacesRedisImpl implements SomeInterfaces {
private final String type = "redis";
#Override
public void send(String message) {
System.out.println(message + "through Redis");
}
#Override
public String getType() {
return this.type;
}
}
master
#Component
public class SomeInterfacesMaster {
private final Set<SomeInterfaces> someInterfaces;
public SomeInterfacesMaster(Set<SomeInterfaces> someInterfaces) {
this.someInterfaces = someInterfaces;
}
public void sendMaster(String type){
Optional<SomeInterfaces> service =
someInterfaces
.stream()
.filter(service ->
service.getType().equals(type)
)
.findFirst();
SomeInterfaces someService =
service
.orElseThrow(() -> new RuntimeException("There is not such way for sending messages."));
someService .send(" Hello. It is a letter to ....");
}
}
test
#SpringBootTest
public class MultiImplementation {
}
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
class SomeInterfacesMasterTest extends MultiImplementation {
#Autowired
private SomeInterfacesMaster someInterfacesMaster;
#Test
void sendMaster() {
someInterfacesMaster.sendMaster("kafka");
}
}
Thus, according to the Open/Closed principle, we only need to add an implementation without breaking existing code.
#Component
public class SomeInterfacesRabbitImpl implements SomeInterfaces {
private final String type = "rabbit";
#Override
public void send(String message) {
System.out.println(message + "through Rabbit");
}
#Override
public String getType() {
return this.type;
}
}
test-v2
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
class SomeInterfacesMasterTestV2 extends MultiImplementation {
#Autowired
private SomeInterfacesMaster someInterfacesMaster;
#Test
void sendMasterV2() {
someInterfacesMaster.sendMaster("rabbit");
}
}
If we have multiple implementations of the same interface, Spring needs to know which one it should be autowired into a class. Here is a simple example of validator for mobile number and email address of Employee:-
Employee Class:
public class Employee {
private String mobileNumber;
private String emailAddress;
...
/** Getters & Setters omitted **/
}
Interface EmployeeValidator:
public interface EmployeeValidator {
public Employee validate(Employee employee);
}
First implementation class for Mobile Number Validator:
#Component(value="EmployeeMobileValidator")
public class EmployeeMobileValidator implements EmployeeValidator {
#Override
public Employee validate(Employee employee) {
//Mobile number Validation logic goes here.
}
}
Second implementation class for Email address Validator:
#Component(value="EmployeeEmailValidator")
public class EmployeeEmailValidator implements EmployeeValidator {
#Override
public Employee validate(Employee employee) {
//Email address validation logic goes here.
}
}
We can now autowired these above validators individually into a class.
Employee Service Interface:
public interface EmployeeService {
public void handleEmployee(Employee employee);
}
Employee Service Implementation Class
#Service
public class EmployeeServiceImpl implements EmployeeService {
/** Autowire validators individually **/
#Autowired
#Qualifier("EmployeeMobileValidator") // Autowired using qualifier for mobile validator
private EmployeeValidator mobileValidator;
#Autowired
#Qualifier("EmployeeEmailValidator") // Autowired using qualifier for email valodator
private EmployeeValidator emailValidator;
#Override
public void handleEmployee(Employee employee) {
/**You can use just one instance if you need**/
employee = mobileValidator.validate(employee);
}
}
I'm having a Spring boot application in which based on a variable, I need to call corresponding implementation classes of an interface. This is what I have right now:
public interface Parent{
public void call();
}
public class ABC implements Parent{
public void call(){
System.out.println("Called ABC");
}
}
public class XYZ implements Parent{
public void call(){
System.out.println("Called XYZ");
}
}
#Service("caller")
public class Caller{
#Autowired
protected OrderInfoRepository orderInfoRepository;
AnnotationConfigApplicationContext context;
public Caller(){
context = new AnnotationConfigApplicationContext(Config.class);
}
public void callMethod(String param){
Parent p = (Parent) context.getBean(param+"_Caller");
p.call();
}
}
#Configuration
public class Config{
#Bean(name="ABC_Caller")
public Parent getABC(){
return new ABC();
}
#Bean(name="XYZ_Caller")
public Parent getXYZ(){
return new XYZ();
}
}
#Repository
public interface MyRepo extends Repository<MyDAO, Long> {
// ....
}
Basically what I want to do is, based on the param passed to Caller.callMethod(), I want to add "_Caller" to the param, and call the corresponding implementation class. So, I'm defining a #Configuration class, where I define which implementation class to return. And then using the AnnotationConfigApplicationContext, I get the corresponding bean. This works fine.
The problem I'm having is, when I try to Autowire anything in the implementation classes, I get a NoSuchBeanDefinitionException. For instance, when I autowire in the implementation class ABC
public class ABC implements Parent{
#Autowired
MyRepo myRepo;
public void call(){
System.out.println("Called ABC");
}
}
I get Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.persistence.repositories.MyRepo] when I try to start the application. However, when I do the Autowiring in the Caller class instead, it works fine. I had asked a similar question a while back, but was not able to resolve it. Any ideas?