I try to implement MockitoExtension in Spring Boot with a simple service class. When I implement it via field-set, it works. But when I implement it constructor, i doesn't work.
ExampleService:
#Service
public class ExampleService
{
private final AmqpTemplate requestTemplate;
private final AmqpTemplate resultTemplate;
public ExampleService(#Qualifier("requestTemplate") AmqpTemplate requestTemplate,
#Qualifier("resultTemplate") AmqpTemplate resultTemplate)
{
this.requestTemplate = requestTemplate;
this.resultTemplate = resultTemplate;
}
}
ExampleServiceTest:
#ExtendWith(MockitoExtension.class)
public class ExampleServiceTest
{
#InjectMocks
private ExampleService exampleService;
#Mock(name = "requestTemplate")
private AmqpTemplate requestTemplate;
#Mock(name = "resultTemplate")
private AmqpTemplate resultTemplate;
#Test
public void test1()
{
...
}
}
requestTemplate and resultTemplate looks like same object on test cases and it behaves wrong...
When I implement it via Autowired, it works...
#Service
public class ExampleService
{
#Autowired
private AmqpTemplate requestTemplate;
#Autowired
private AmqpTemplate resultTemplate;
...
}
I wonder the constructor solution and reason why it doesn't work.
Suppose i have a class as,
#Repository
public class StudentServiceDao{
private final StudentClient client;
private final StudentValidator validator;
#Autowired <----
public StudentServiceDao(StudentClient studentClient){
client = studentClient;
validator = new StudentValidator(studentClient.getIdentifier());
}
public List<Student> getStudent(Request request){
StudentRS studentRS= client.getStudentList(request);
validator.validate(studentRS);
return StudentMapper.map(studentRS);
}
}
Now i have another class as,
#Component
public class StudentServiceDaoImpl{
#Autowired
private StudentServiceDao studentServiceDao;
public list<Student> retrieveStudent (Request request){
return studentServiceDao.getStudent(request);
}
}
Now if i remove #Autowired from StudentServiceDao what will happen and why ?
Autowiring can happen multiple ways.
For a few years now (currently 2020) all of these are valid ways to autowire dependencies:
Explicit constructor autowire annotation:
#Repository
public class StudentServiceDao {
private final StudentClient client;
private final StudentValidator validator;
#Autowired
public StudentServiceDao(StudentClient studentClient){
client = studentClient;
validator = new StudentValidator(studentClient.getIdentifier());
}
}
Implicit constructor autowire:
#Repository
public class StudentServiceDao {
private final StudentClient client;
private final StudentValidator validator;
public StudentServiceDao(StudentClient studentClient){
client = studentClient;
validator = new StudentValidator(studentClient.getIdentifier());
}
}
Explicit field autowire:
#Repository
public class StudentServiceDao {
#Autowired
private final StudentClient client;
#Autowired
private final StudentValidator validator;
}
Pick which ever one makes the most sense for you. I personally like implicit constructor. I think it makes instantiating the bean for testing easier with mocks. All types are valid.
5 or 6 years ago, before java config took over, there were other requirements like getters/setters needing to be present, xml files needing to specify all the beans, etc. But those are mostly gone and if you are working on a modern spring app you won't encounter them.
As to why, I have no idea, this is just how it is.
I was trying to create a configuration class
#Configuration
public class AppConfig {
private final SomeBean someBean;
private final AnotherBean anotherBean;
#Autowired
public AppConfig(SomeBean someBean, AnotherBean anotherBean) {
this.someBean = someBean;
this.anotherBean = anotherBean;
}
}
Another approach with
#Configuration
public class AppConfig {
#Autowired
private final SomeBean someBean;
#Autowired
private final AnotherBean anotherBean;
}
Not sure which one I have to go for.
I have seen many codes with the second approach, but not with the first approach.
Any reason for this?
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 have designed a packing structure.
Controller
Delegates (which is helper class) - this class do all the business and return the value to Controllers.
Service
Service Implementation
DAO
DAO Implementation.
I want to implement autowired (Annotation) concept and would like to avoid xml configuration such as service and DAO configuration on spring-bean.xml.
This code is not working if I want to avoid xml configuration.
I have done those changes
bean id :loginDelegate, userService, userDao
added the #Service & #Repository annotation to the corresponding service & DAO implementation.
#Controller("loginController")
public class LoginController {
#Autowired
private LoginDelegate loginDelegate;
public LoginDelegate getLoginDelegate() {
return this.loginDelegate;
}
public void setLoginDelegate(LoginDelegate tLoginDelegate) {
this.loginDelegate = tLoginDelegate;
}
#RequestMapping(value="/login.do",method=RequestMethod.GET)
public ModelAndView displayLogin(HttpServletRequest request, HttpServletResponse response) {
log.info("<---displayLogin()--->");
ModelAndView model = new ModelAndView("login");
LoginBean loginBean = new LoginBean();
model.addObject("loginBean", loginBean);
return model;
}
}
public class LoginDelegate {
#Autowired
private IUserService userService;
public IUserService getUserService() {
return this.userService;
}
public void setUserService(IUserService userService) {
this.userService = userService;
}
public boolean isValidUser(String username, String password) throws Exception {
return userService.isValidUser(username, password);
}
}
public interface IUserService {
public boolean isValidUser(UserBean userObj);
public int addUsers(UserBean userObj);
}
public class UserServiceImpl implements IUserService {
#Autowired
private IUserDao userDao;
public IUserDao getUserDao() {
return this.userDao;
}
public void setUserDao(IUserDao userDao) {
this.userDao = userDao;
}
public boolean isValidUser(UserBean userObj) {
return userDao.isExistUser(userObj);
}
#Override
public int addUser(final UserBean userObj) {
return userDao.saveUserDetails(userObj);
}
}
public interface IUserDao {
public boolean isExistUser(UserBean userObj);
public int saveUserDetails(UserBean userObj);
}
public class UserDaoImpl implements IUserDao {
#Autowired
UserBean userObj;
#Autowired
DataSource dataSource ;
public DataSource getDataSource(){
return this.dataSource;
}
public void setDataSource(DataSource dataSource){
this.dataSource = dataSource;
}
Use Java-based configuration if you want to completely get rid of XML-based configuration
#Configuration
#ComponentScan(basePackages = "com.acme")
public class AppConfig {
...
}
The above normal Java class when annotated with #Configuration, makes it a 'Spring Configuration class' (analogous to XML-based configuration).
#ComponentScan annotation scans for classes annotated with #Component, #Controller, #Service, #Repository classes from the package defined during start-up time to get them registered as Spring beans. This can be done in XML also with <context:component-scan base-package="com.acme" />
Refer:http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/beans.html#beans-java-instantiating-container-scan