#SpringBootApplication
public class ImportCSV {
#Autowired
private static PersonRepository personRepository; //does not seem to work
public static void main(String args[]) throws IOException {
SpringApplication.run(ImportCSV.class, args);
Person person = new Person();
// Add a bunch of setters for person
personRepository.save(person); //personRepository is null
}
}
public interface PersonRepository extends JpaRepository<Person, Long>{
}
#Data
#Entity
#Table(name = "Persons")
#NoArgsConstructor
public class Person {
/*Declare relevant fields here*/
}
Please see above code. 'personRepository' is null. How do I fix this? What am I doing wrong -- how does Autowire work?
Spring does not inject into static fields. So you have to remove the static keyword from the personRepository field. The compiler will complain then, that you cannot access a non-static field from a static method. To solve this, implement the ApplicationRunner interface, which defines a run method. In that method, you can run all the code, that should be run after the Spring Boot application is started, e.g. for initializing any data in the database etc.
That would be the proper Spring Boot way to execute code after the application is started.
For even more cleaner code then, you can create a separate class, that implements the ApplicationRunner interface and move the code there.
Example:
#SpringBootApplication
public class ImportCSV implements ApplicationRunner {
#Autowired
private PersonRepository personRepository; //does not seem to work
public static void main(String args[]) throws IOException {
SpringApplication.run(ImportCSV.class, args);
}
#Override
public void run(ApplicationArguments args) throws Exception {
Person person = new Person();
personRepository.save(person);
}
}
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 am getting "Couldn't find PersistentEntity for type class" error when I am using #EnableMongoAuditing features along with MongoRepository.
This happens when I save a document when collection isn't already present in database.
I tried whatever is mentioned in:
https://github.com/spring-projects/spring-boot/issues/12023
https://jira.spring.io/browse/DATAMONGO-1999
Spring boot mongodb auditing error
but nothing is working.
Mentioned things are:
Extend MongoConfig by AbstractMongoConfiguration and override all methods.
Here is my code which reproduced the same error:
MongoConfig class
#Configuration
public class MongoConfig extends AbstractMongoConfiguration {
#Value("${spring.data.mongodb.host}")
private String mongoHost;
#Value("${spring.data.mongodb.port}")
private String mongoPort;
#Value("${spring.data.mongodb.database}")
private String mongoDB;
#Override
public MongoDbFactory mongoDbFactory() {
return new SimpleMongoDbFactory(new MongoClient(mongoHost + ":" + mongoPort), mongoDB);
}
#Override
public MongoClient mongoClient() {
return new MongoClient(mongoHost, Integer.parseInt(mongoPort));
}
#Override
public MongoTemplate mongoTemplate() {
return new MongoTemplate(mongoDbFactory());
}
#Override
public MappingMongoConverter mappingMongoConverter() {
return new MappingMongoConverter(new DefaultDbRefResolver(mongoDbFactory()), new MongoMappingContext());
}
#Override
protected String getDatabaseName() {
return mongoDB;
}
}
Person Collection class
#Document
public class Person {
#Id
private String id;
private String name;
#CreatedDate
private LocalDateTime createdAt;
#LastModifiedDate
private LocalDateTime lastModified;
// Getter Setters Constructors omitted for brevity
}
Main Application class
#EnableMongoAuditing
#EnableMongoRepositories ({"com.example.*", "org.apache.*"})
#SpringBootApplication
#ComponentScan({"com.example.*", "org.apache.*"})
public class DemoApplication implements CommandLineRunner {
#Autowired
PersonRepository personRepository;
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
Person p1 = new Person("1", "prakhar");
personRepository.save(p1);
}
}
Expected Result is Person entity should be saved in database.
Actual Result is "Couldn't find PersistentEntity for type class Person" error
Looks like you ran into https://github.com/spring-projects/spring-boot/issues/12023
Extending AbstractMongoConfiguration will switch off Spring Boot's auto-configuration of various Mongo components and also customises the base packages that are used to scan for mappings. I would recommend that you don't use it in Spring Boot.
Update
I managed to get the example running with the configuration as simple as
#Configuration
public class MongoConfig {
#Value("${spring.data.mongodb.host}")
private String mongoHost;
#Value("${spring.data.mongodb.port}")
private String mongoPort;
#Value("${spring.data.mongodb.database}")
private String mongoDB;
#Bean
public MongoDbFactory mongoDbFactory() {
return new SimpleMongoDbFactory(new MongoClient(mongoHost + ":" + mongoPort), mongoDB);
}
#Bean
public MongoClient mongoClient() {
return new MongoClient(mongoHost, Integer.parseInt(mongoPort));
}
}
and the app class
#EnableMongoAuditing
#SpringBootApplication
public class DemoApplication implements CommandLineRunner {
#Autowired
PersonRepository personRepository;
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
#Override
public void run(String... args) throws Exception {
Thread.sleep(2000);
Person p1 = new Person("1", "prakhar");
personRepository.save(p1);
}
}
Notice that I followed my own advice and did't inherit from AbstractMongoConfiguration
Explanation
The problem lies in the initialization of
#Bean
public MappingMongoConverter mappingMongoConverter() {
return new MappingMongoConverter(new DefaultDbRefResolver(mongoDbFactory()), new MongoMappingContext());
}
You simply call MongoMappingContext constructor, without calling setInitialEntitySet. Compare that with MongoDataConfiguration auto-configuration class.
#Bean
#ConditionalOnMissingBean
public MongoMappingContext mongoMappingContext(MongoCustomConversions conversions)
throws ClassNotFoundException {
MongoMappingContext context = new MongoMappingContext();
context.setInitialEntitySet(new EntityScanner(this.applicationContext)
.scan(Document.class, Persistent.class));
Class<?> strategyClass = this.properties.getFieldNamingStrategy();
if (strategyClass != null) {
context.setFieldNamingStrategy(
(FieldNamingStrategy) BeanUtils.instantiateClass(strategyClass));
}
context.setSimpleTypeHolder(conversions.getSimpleTypeHolder());
return context;
}
Even worse, you don't register MongoMappingContext as a managed bean.
Due to this fact, auto-configuration class is still created. This leads to a race condition, I tried to run the original code and could easily reproduce the error, but with a breakpoint in AbstractMappingContext.addPersistentEntity the test always passed.
For me I resolved this issue by adding following method in MongoConfig if your class extends from AbstractMongoConfiguration
#Override
protected String getMappingBasePackage() {
return "com.companyName.modulename"
}
If MongoConfig extends from MongoConfigurationSupport then add below method
#Override
protected Collection<String> getMappingBasePackages() {
return Arrays.asList("com.companyName.module1","com.companyName.module2");
}
Note that in later case I can specify multiple package names as base packages.
I have interface like this
#Repository
public interface CarRepository extends JpaRepository<Car, Long> {
}
In class adnotated #RestController Spring is able to wired with proper field.
But how can I do this if I want to create class without any adnotation in spring? I have to create implementation of this repository? If yes, can I do it like spring is?
Inject
private final ConfigurableApplicationContext configurableApplicationContext;
into the class instantiating your desired class. Then call:
YourClass yourClass = (YourClass) configurableApplicationContext.getBeanFactory().initializeBean(new YourClass(), "YourClassName");
yourClass will then hold an instance of YourClass which has been initialized as if it was a Spring #Component (or a #RestController, which is the same from the dependency-injection point of view).
#SpringBootApplication
public class MainApplication extends SpringBootServletInitializer implements ApplicationContextAware {
private static ApplicationContext appContext;
public static void main(String[] args) {
SpringApplication.run(CrawlerApplication.class, args);
}
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.appContext = applicationContext;
}
....
MainApplication.getAppContext().getBean(CarRepository.class)
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 trying to figure out how to build a Spring Boot standalone app. Of course to have things autowired requires some initial context starting point. If I just try to Autowire a class to run a job it is null even if I make it static.
Is there a way to use Spring #Services in a standalone non-web app?
#SpringBootApplication
public class MyApplication {
#Autowired
private static JobRunnerService job;
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
job.send(); //job is null !
}
}
So first wired in a static JobRunnerService to the main running MyApplication the JobRunner(Service) Class has a non-static SshSessionService wired into it.
the SshSession(Service) finally just has a no-arg constructor.
#Service("jobRunnerService")
public final class JobRunner implements JobRunnerService{
#Autowired
private SshSessionService ssh;
#Autowired
public JobRunner(SshSessionService ssh){
this.ssh = ssh;
}
public void sendToAgent() { ....
}
#Service("sshSessionService")
public class SshSession implements SshSessionService {
public SshSession() {
}
}
It starts off being null at the JobRunnerService job reference.
Several different solutions comes to mind:
If you take a look at the SpringApplication.run() method you will notice that it returns a ApplicationContext. From that, you can fetch the JobRunnerService, e.g.
#SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
ApplicationContext ctx = SpringApplication.run(MyApplication.class, args);
JobRunnerService job = ctx.getBean(JobRunnerService.class);
job.send();
}
}
Another solution is to use #PostConstruct annotation for the send() method:
#Service("jobRunnerService")
public class JobRunner implements JobRunnerService {
#PostConstruct
public void send() { ... }
}
However in your case, I would implement the ApplicationRunner interface, either as a separate bean which autowires the JobRunnerService and then calls its send() method
#Component
public class SendRunner implements ApplicationRunner {
#Autowired
private JobRunnerService job;
#Override
public void run(ApplicationArguments args) {
job.send();
}
}
or let the JobRunner implement the ApplicationRunner interface directly:
#Service("jobRunnerService")
public class JobRunner implements JobRunnerService, ApplicationRunner {
#Override
public void send() { ... }
#Override
public void run(ApplicationArguments args) {
send();
}
}
You haven't provided the code for JobRunnerService but I am assuming it has a default constructor and that it is annotated by #Component for Spring to figure it out as a bean before you can actually autowire it. your job is null probably because it's not able to find an autowired bean for JobRunnerService and that's probably because you don't have an identifier for Spring to scan and create bean of type JobRunnerService
You can use #Servicesor #Component to the JobRunnerService class then add annotation #ComponentScan("package of JobRunnerService") below #SpringBootApplication, see this link:
How to scan multiple paths using the #ComponentScan annotation?
You need a few steps to get your standalone app working:
A class with main() method.
A #SpringBootApplication annotation to your main class.
And a call to the SpringApplication.run() method.
package com.example.myproject;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication // same as #Configuration #EnableAutoConfiguration #ComponentScan
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
As noted, the #SpringBootApplication is a composite annotation which consist of #Configuration #EnableAutoConfiguration and #ComponentScan. In other words, it can be replaced by the three latter annotations. Alternatively, you can use the alias scanBasePackage or scanBasePackageClasses to customize which directories that should be used for component scanning.
The example is copied from the #SpringBootApplication paragraph in the Spring Boot reference docs (see link above). If you would like to quick start your project, complete with build scripts (Maven or Gradle), dependencies, etc, you can generate a project skeleton using the Spring Initializr
I'm trying to run as Thread/runnable now as mentioned in the Spring document 3. Task Execution and Scheduling..
import org.springframework.core.task.TaskExecutor;
public class TaskExecutorExample {
private class MessagePrinterTask implements Runnable {
private String message;
public MessagePrinterTask(String message) {
this.message = message;
}
public void run() {
System.out.println(message);
}
}
private TaskExecutor taskExecutor;
public TaskExecutorExample(TaskExecutor taskExecutor) {
this.taskExecutor = taskExecutor;
}
public void printMessages() {
for(int i = 0; i < 25; i++) {
taskExecutor.execute(new MessagePrinterTask("Message" + i));
}
}
}
So in my case I'm trying...
#Service("jobRunnerService")
#Component
public class JobRunner implements JobRunnerService, ApplicationRunner{
#Autowired
public TaskExecutor taskExecutor;
#Autowired
private SshSessionService ssh;
private class JobTask implements Runnable{
public void run(){
Boolean success = connectToAgent();
if(success){
log.debug("CONNECTED!!!");
}
}
}
/**
* Construct JobRunner with TaskExecutor
* #param taskExecutor
*/
#Autowired
public JobRunner(TaskExecutor taskExecutor, SshSessionService ssh) {
this.taskExecutor = taskExecutor;
this.ssh = ssh;
}
private Map<String, String> sessionParams;
private final Logger log = LoggerFactory.getLogger(this.getClass());
#Override
public void run(ApplicationArguments args) {
/**
* Starting point of application
*
*/
taskExecutor.execute(new JobTask());
}
just getting org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.core.task.TaskExecutor] found for dependency
How can i get the imported lib to be accepted as a TaskExecutor Bean ??