I've created this custom test configuration:
#TestConfiguration
public static class RestTemplateTestConfiguration {
#Bean
#Primary
public static ApplicationDao applicationDao() {
ApplicationDao mock = Mockito.mock(ApplicationDao.class);
// some stuff code
return mock;
}
}
I've set a breakpoint on applicationDao, but it's never reached, and therefore mock is never injected.
EDIT
ApplicationDao is an #Repository annotated class:
#Repository
public interface ApplicationDao extends MongoRepository<Application, String> {
So, how could I override this #Repository annotated AplicationDao?
Currently, I'm getting this message when spring starts:
Skipping bean definition for [BeanMethod:name=applicationDao,declaringClass=net.gencat.transversal.espaidoc.functional.references.GroupReferencesTest$RestTemplateTestConfiguration]: a definition for bean 'applicationDao' already exists. This top-level bean definition is considered as an override.
Any ideas?
If your method applicationDao() is never called it means that your spring boot is not scanning the package where RestTemplateTestConfiguration is located.
The simplest solutions is to move the configuration under the same package (or its children) as the one that contains the class annotated with #SpringBootApplication.
OBS : This rule applies even though the configuration is in the test directory instead of main.
Another solution is to add #ComponentScan with the configuration package or to use #Import(RestTemplateTestConfiguration.class) at your spring boot test level.
SUGGESTION:
For your problem you can use:
#Mock
ApplicationDao applicationDao;
and if you have another service that uses this one to use:
#InjectMock
MyService myService;
Related
I've a #RestController which has only one dependency in field #Autowire
that dependency is #component, that component Class definition has some autowired fields which are #service and those services have some #repositories.
In this whole flow I've kafka, Quartz, Cassandra and DB2
So when I was creating a Unit test case for my controller, I dont want to setup whole application. so I decided to use #webMvcTest and used #MockBean on my only one dependency of controller class.
But my Test is throwing and exception because its trying to create a Dao bean, which is marked as #repository.
#ActiveProfiles("test")
#WebMvcTest(controllers = MyControllerTest .class)
class MyControllerTest {
#MockBean
MyControllerDependency dependency;
#Autowired
MockMvc mockMvc;
#Test
void test_something() throws Exception {
assert(true);
}
}
Here is oversimplified version of code
#Component
class MyControllerDependency {
#AutoiWired
MyCustomService service;
}
#Service
class MyCustomService{
#Autowired
MyCustomDao dao;
}
#Repository
class MyCustomDao{
#Autowired
private JdbcTemplate template;
}
I'm getting following exception in test.
Exception
***************************
APPLICATION FAILED TO START
***************************
Description:
Field template in com.....MyCustomDao` required a bean of type 'org.springframework.jdbc.core.JdbcTemplate' that could not be found.
Question is, When I'm using #WebMvcTest slice and already mocking the only required dependency MyControllerDependency then why spring test context is trying to load MyCustomDao which is annotated as #Repository.
I can do integration testing with SpringbootTest & AutoconfigureMockMVC, but for writing Junit test just for controller, I need to use WebMvcTest slice. which is creating a problem.
I ran into a similar problem where I want to test only my controller using #WebMvcTest, but the spring context was trying to create nondependent spring beans and was failing as below.
Failed to load ApplicationContext
java.lang.IllegalStateException: Failed to load ApplicationContext
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'TestController' defined in file ...
Solution: load only the controller your testing for an example like #ContextConfiguration(classes = DemoController.class).
Also, find below a complete sample
#WebMvcTest
#ContextConfiguration(classes = DemoController.class)
public class DemoControllerTest {
#Autowired
MockMvc mockMvc;
#MockBean
DemoService demoService;
#Test
public void testGetAllProductCodes_withOutData() throws Exception {
when(productCodeService.getAllProductCodes()).thenReturn(new ArrayList<ProductCodes>());
mockMvc.perform(MockMvcRequestBuilders.get("/services/productCodes")).andExpect(MockMvcResultMatchers.status().isNoContent());
}
}
}
Do you have any #ComponentScan("...") annotation active on your #SpringBootApplication?
As described in Spring Boot Reference Documentation:
Another source of confusion is classpath scanning. Assume that, while you structured your code in a sensible way, you need to scan an additional package. Your application may resemble the following code:
#SpringBootApplication
#ComponentScan({ "com.example.app", "com.example.another" })
public class MyApplication {
// ...
}
Doing so effectively overrides the default component scan directive with the side effect of scanning those two packages regardless of the slice that you chose. For instance, a #DataJpaTest seems to suddenly scan components and user configurations of your application. Again, moving the custom directive to a separate class is a good way to fix this issue.
One solution is to create a seperate #Configuration that is annotated with #ComponentScan. When creating a #WebMvcTest the configuration (and its component scan is ignored).
#Configuration
#ComponentScan("com.example.another")
public class DbConfig {
}
This usually happens when you have explicit #ComponentScan annotation on the spring boot main application class.
The #ComponentScan annotation suppresses the default component scanning mechanism that happens with #Webmvctest where it scans up the package hierarchy and apply excludeFilters to find only controller and its related classes.
When you mock your bean using #MockBean annotation you should define what that mocked bean should do when you call it's method, you usually do this using when in Mockito. In your case it can be done this way:
#ActiveProfiles("test")
#WebMvcTest
class MyControllerTest {
#MockBean
MyControllerDependency dependency;
#Autowired
MockMvc mockMvc;
#Test
void test_something() throws Exception {
when(dependency.sample()).thenReturn("Hello, Mock");
mockMvc.perform(get("/api/test/restpoint")
.accept(MediaType.APPLICATION_JSON))
.andDo(print())
.andExpect(status().isOk());
}
}
At this line:
when(dependency.sample()).thenReturn("Hello, Mock");
Instead of dependency.sample() you should put whatever method of MyControllerDependency class your controller call when you send a GET request to /api/test/restpoint path and with thenReturn("Hello, Mock") you define what is the mocked output of that method (when it gets called by your controller in your Unit test).
For example, have a class like as follows.
First XService service in class A is not null but second XService service in AmountValidator is null.I get NullPointerException I try to create bean new it works and then I get same exception when call AmountValidateService outsideRestService in XService.
How can I use XService everywhere that I use #Autowired annotation.
My main class:
#Service
class A extends AbstractA implements IA {
#Autowired
XService service; //first autowired definition. code go to check() method. service not null now.
public doSometing(){
validator.check();
service.methodA();
super.AbstractMethod();
}
}
Validator class used in class A :
class Validator<T> implements IValidator<T> {
public void check(){
rule.check(); // rule have a implements IValidator eg: amountValidator, dateValidator class
}
}
AmountValidator added to rule in class Validator.
#Component
class AmountValidator implements IValidator<T>{
#Autowired
XService service; // code comes here service is null. same service class mentioned above class A.
#Override
public void check(){
service.validateAmount(); // nullPointerException.
}
}
My main Service
#Component
class XService {
#Autowired
AmountValidateService outsideRestService;
public validateAmount(){
outsideRestService.validate(); // nullPointer when create XService with the `New` keyword
}
}
You have an error cause you are trying to create components/beans/services yourself. As i mentioned in comment when you create components yourself it - #Autowired doesn't work - thats you've got NPE
All classes annotated with #Component, #Service are considered special classes which are instantiated by Spring automatically via DI, instantiating them with new defeats the purpose of DI.
These special classes are named Spring Beans.
Every time the application starts, the framework instances all Spring Beans, and all #Autowired fields are injected by Spring automatically. But the Spring Beans must be defined somewhere in the class path. Else you will receive a NoSuchBeanDefinitionException
As an attempt to answer the question, since I don't have a stack trace nor all the Spring Bean definitions:
When you instantiate XService using new XService() your new instance will not actually initialize the field AmountValidateService outsideRestService, effectively leaving it as null.
You may set the field yourself but as I mentioned earlier, it defeats the purpose of DI
Your question is not complex, it is incomplete.
It might be a very simple question for you.But I read lots of documents and I am totally confused.We can use #Component instead of #Bean or #Bean instead of #Component(as well as #Repository #Service #Controller) ?
Cheers
Component
#Component also for #Service and #Repository are used to auto-detect and auto-configure beans using classpath scanning.
As long as these classes are in under our base package or Spring is aware of another package to scan, a new bean will be created for each of these classes
Bean and Component are mapped as one to one i.e one bean per Class.
These annotations (#Component, #Service, #Repository) are Class level annotations.
Example:
Lets Say we have a UserService Class which contains all methods for User Operation.
#Service
public class UserService {
#Autowired
private UserRepository userRepository;
#Override
public User findByUsername( String username ) throws UsernameNotFoundException {
User u = userRepository.findByUsername( username );
return u;
}
public List<User> findAll() throws AccessDeniedException {
List<User> result = userRepository.findAll();
return result;
}
}
Spring will create a Bean for UserService and we can use this at multiple location/classes.
#Bean
#Bean is used to declare a single bean, rather than letting Spring do it automatically as in case of Component.
It decouples the declaration of the bean from the class definition, and lets you create and configure beans exactly how you choose.
#Bean are used at method level and can be configured as required
eg:
#Configuration
#EnableWebSecurity
#EnableGlobalMethodSecurity(prePostEnabled = true)
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
#Bean
public SpringTemplateEngine springTemplateEngine()
{
SpringTemplateEngine templateEngine = new SpringTemplateEngine();
templateEngine.addTemplateResolver(htmlTemplateResolver());
return templateEngine;
}
#Bean
public SpringResourceTemplateResolver htmlTemplateResolver()
{
SpringResourceTemplateResolver emailTemplateResolver = new SpringResourceTemplateResolver();
emailTemplateResolver.setPrefix("classpath:/static/template/");
emailTemplateResolver.setSuffix(".html");
emailTemplateResolver.setTemplateMode("HTML");
emailTemplateResolver.setCharacterEncoding(StandardCharsets.UTF_8.name());
return emailTemplateResolver;
}
...
Read more about Stereotype Annotations here.
#Bean is used to define a method as a producer, which tells Spring to use that method to retrieve an object of the method return type and inject that object as a dependency whenever it's required.
#Component is used to define a class as a Spring component, which tells Spring to create an object (if it's Singleton) from and take care of it's lifecycle and dependencies and inject that object whenever it's required.
#Service and #Repository are basically just like #Component and AFAIK they are just for better grouping of your components.
#Service for Defining your service classes where you have your business logic, and #Repository for Defining your repository classes where you interact with an underlying system like database.
#Component
If we mark a class with #Component or one of the other Stereotype annotations these classes will be auto-detected using classpath scanning. As long as these classes are in under our base package or Spring is aware of another package to scan, a new bean will be created for each of these classes.
package com.beanvscomponent.controller;
import org.springframework.stereotype.Controller;
#Controller
public class HomeController {
public String home(){
return "Hello, World!";
}
}
There's an implicit one-to-one mapping between the annotated class and the bean (i.e. one bean per class). Control of wiring is quite limited with this approach since it's purely declarative. It is also important to note that the stereotype annotations are class level annotations.
#Bean
#Bean is used to explicitly declare a single bean, rather than letting Spring do it automatically like we did with #Controller. It decouples the declaration of the bean from the class definition and lets you create and configure beans exactly how you choose. With #Bean you aren't placing this annotation at the class level. If you tried to do that you would get an invalid type error. The #Bean documentation defines it as:
Indicates that a method produces a bean to be managed by the Spring container.
Typically, #Bean methods are declared within #Configuration classes.We have a user class that we needed to instantiate and then create a bean using that instance. This is where I said earlier that we have a little more control over how the bean is defined.
package com.beanvscomponent;
public class User {
private String first;
private String last;
public User(String first, String last) {
this.first = first;
this.last = last;
}
}
As i mentioned earlier #Bean methods should be declared within #Configuration classes.
package com.beanvscomponent;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
#Configuration
public class ApplicationConfig {
#Bean
public User superUser() {
return new User("Partho","Bappy");
}
}
The name of the method is actually going to be the name of our bean. If we pull up the /beans endpoint in the actuator we can see the bean defined.
{
"beans": "superUser",
"aliases": [],
"scope": "singleton",
"type": "com.beanvscomponent.User",
"resource": "class path resource
[com/beanvscomponent/ApplicationConfig.class]",
"dependencies": []
}
#Component vs #Bean
I hope that cleared up some things on when to use #Component and when to use #Bean. It can be a little confusing but as you start to write more applications it will become pretty natural.
I have the following classes:
#ComponentScan
public class CDPlayerConfig {
#Autowired
private static CompactDisc cd;
public static void main(String[] args) {
ApplicationContext context = new AnnotationConfigApplicationContext(CDPlayerConfig.class);
CompactDisc cd = context.getBean(CompactDisc.class);
System.out.println(cd);
}
}
public interface CompactDisc {
void play();
}
#Component
public class SgtPeppers implements CompactDisc {
public void play() {
System.out.println("play song....");
}
}
When I run the class CDPlayerConfig, the program runs successfully. However, if I remove the ComponentScan annotation to CompactDisc interface or SgtPeppers I get the following error:
Exception in thread "main"
org.springframework.beans.factory.NoSuchBeanDefinitionException: No
qualifying bean of type 'CompactDisc' available
I think that ComponentScan annotation marks the package where Spring looks for beans. CDPlayerConfig, CompactDisc and SgtPeppers are all placed in the same package, so allegedly moving ComponentScan annotation from one class to another should not make a difference.
If so, why do I get an error?
For #ComponentScan to work you have to "tell" spring where to search, or it must find it with help of other, already loaded, #ComponentScan annotated class (your class must be then annotated also with #Component, #Configuration etc. so it could be found).
In your case, you register application context in the first line of main method - you have specified there to load CDPlayerConfig.class which is #ComponentScan annotated so now spring can automatically find other beans in the package:
ApplicationContext context =
new AnnotationConfigApplicationContext(CDPlayerConfig.class);
If you want to move #ComponentScan to another class, you have to change class registered in AnnotationConfigApplicationContext to some #ComponentScan annotated class:
SgtPeppers:
#Component
#ComponentScan
public class SgtPeppers implements CompactDisc {
(...)
Main in CDPlayerConfig:
ApplicationContext context =
new AnnotationConfigApplicationContext(SgtPeppers.class);
Note you should register context from concrete classes (not interfaces).
Also, above sample would work even without #ComponentScan annotation on SgtPeppers, but then beans defined in other classes from the package wouldn't be found.
#ComponentScan creates beans using both #Configuration and #Component. Both these annotations work fine when swapped. What is the difference then?
#Configuration Indicates that a class declares one or more #Bean
methods and may be processed by the Spring container to generate bean
definitions and service requests for those beans at runtime
#Component Indicates that an annotated class is a "component". Such
classes are considered as candidates for auto-detection when using
annotation-based configuration and classpath scanning.
#Configuration is meta-annotated with #Component, therefore
#Configuration classes are candidates for component scanning
You can see more here:
http://docs.spring.io/spring-framework/docs/4.0.4.RELEASE/javadoc-api/org/springframework/context/annotation/Configuration.html
A #Configuration is also a #Component, but a #Component cannot act like a #Configuration.
Actually answer is not complete, is it true that:
#Component Indicates that an annotated class is a "component". Such
classes are considered as candidates for auto-detection when using
annotation-based configuration and classpath scanning.
But you do can create i.e MyConfiguration.java class then stereotype with #Component and add #Beans declaration to it. In this way it will looks as a configuration, main difference is that when annotated class with #Configuration #Bean annotated methods are proxy using CGLIB which made in code calls after the first one to return bean from context instead of execute method again and create another instance as happens when using #Component with #Bean
There is a very subtle difference between them. Let me provide a very quick outlook to this.
Consider the below scenario:
#Configuration
public class MyConfig {
#Bean
public ServiceA aService(){
return new ServiceA();
}
#Bean
public ServiceB bService(){
return new ServiceB(aService());
}
}
Note that ServiceB bean has a dependecy on ServiceA and this is not autowired. Instead, the way it's written implies that a new instance is created, which is not actually created by Spring. You, the programmer, did it with the new keyword instead.
So, if we do use #Configuration, then it uses CGLIB proxying, and in this situation it creates a singleton bean managed by the Spring context. If you invoke it multiple times, it returns the same bean that was created by Spring - sort of autowiring effect.
Whereas if you use #Component, it won't do this proxying and will simply return a new instance every time the method is invoked, instead of providing the Spring managed instance. (Remember that a Spring bean is something that is managed by the Spring container, and, as a developer, it's your job is to pull them in, e.g. with #Autowired.
The same #Component effect can be achieved with #Configuration(proxyEnabled= false) (This is also referred to as bean light mode processing). So, in light mode, you would end up doing something like this:
#Configuration(proxyEnabled = false) // Lite mode, same effect as #Component
public class MyConfig {
#Bean
public ServiceA aService() {
return new ServiceA();
}
#Autowired
#Bean
public ServiceB bService(ServiceA aServiceBean){
return new ServiceB(aServiceBean);
}
}
Refer here for a more elaborate explanation
Hope that helps! Happy Coding!
#Configuration - It is like beans.xml but Java-based bean configuration. It means class annotated with this annotation is the place where beans are configured and will be a candidate for auto-detection. In this class, methods are annotated with #Bean which return an object of the class.
Example:
#Configuration
public class ConfigClass {
#Bean
public UserClass getObject() {
return new UserClass();
}
}
#Component - You cannot autowire (#Autowired) any class if it is not marked with #Component. It means when you want to autowire any class using annotation that class should be annotated with #Component.
Example:
#Component
public class A { .... }
public class B {
#Autowired
A a;
.....
.....
}
Spring Document for reference:
https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/annotation/Configuration.html
#Component is imported by default with #Configuration. controllers, service, and repostory are children components (along with Configuration). They are also candidate for auto-detection.
I am extending on #reus's answer.
#Configuration Indicates that a class declares one or more #Bean methods and may be processed by the Spring container to generate bean definitions and service requests for those beans at runtime.
If you look at the #Configuration class, you will see that it is meta-annotated with #Component.
#Target(value=TYPE)
#Retention(value=RUNTIME)
#Documented
#Component
public #interface Configuration
#Bean is enables us to define the dependency in any way we like, this is why the #Bean annotation goes above a methods and we manually create a bean object and return it from that method. #Component enables us to define a dependency quickly, that is why #Component goes above classes. We only inject it wherever we need.
Collectively these 3 points says that- to quickly define a bean, we can annotate the class with #Component. To define a bean as we like (support custom requirements), we can write the bean definition using #Bean inside a #Configuration annotated class.
Apart from the differences highlighted by reos.
The reason why #Configuration cannot be replaced by #Component is as below:
The difference is in how the inter bean dependency is handled.
Refer the link for a detailed explanation with example:
Difference between Configuration and Component