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Difference between CDI and EJB singleton (#6915)

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* Singleton injection examples and tests added

* code and tests implemented
This commit is contained in:
enpy 2019-05-08 16:40:54 +02:00 committed by maibin
parent 57ec69ad3b
commit 8209ec4a1f
5 changed files with 286 additions and 0 deletions
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28
jee-7/src/main/java/com/baeldung/singleton/Car.java Normal file
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package com.baeldung.singleton;
public class Car {
private String type;
private String model;
private boolean serviced = false;
public Car(String type, String model) {
super();
this.type = type;
this.model = model;
}
public boolean isServiced () {
return serviced;
}
public void setServiced(Boolean serviced) {
this.serviced = serviced;
}
@Override
public String toString() {
return "Car [type=" + type + ", model=" + model + "]";
}
}

23
jee-7/src/main/java/com/baeldung/singleton/CarServiceBean.java Normal file
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package com.baeldung.singleton;
import java.util.UUID;
import javax.enterprise.context.Dependent;
import org.springframework.web.context.annotation.RequestScope;
@RequestScope
public class CarServiceBean {
private UUID id = UUID.randomUUID();
public UUID getId() {
return this.id;
}
@Override
public String toString() {
return "CarService [id=" + id + "]";
}
}

46
jee-7/src/main/java/com/baeldung/singleton/CarServiceEjbSingleton.java Normal file
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package com.baeldung.singleton;
import java.util.UUID;
import javax.ejb.Singleton;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@Singleton
public class CarServiceEjbSingleton {
private static Logger LOG = LoggerFactory.getLogger(CarServiceEjbSingleton.class);
private UUID id = UUID.randomUUID();
private static int serviceQueue;
public UUID getId() {
return this.id;
}
@Override
public String toString() {
return "CarServiceEjbSingleton [id=" + id + "]";
}
public int service(Car car) {
serviceQueue++;
LOG.info("Car {} is being serviced @ CarServiceEjbSingleton - serviceQueue: {}", car, serviceQueue);
simulateService(car);
serviceQueue--;
LOG.info("Car service for {} is completed - serviceQueue: {}", car, serviceQueue);
return serviceQueue;
}
private void simulateService(Car car) {
try {
Thread.sleep(100);
car.setServiced(true);
} catch (InterruptedException e) {
LOG.error("CarServiceEjbSingleton::InterruptedException: {}", e);
}
}
}

47
jee-7/src/main/java/com/baeldung/singleton/CarServiceSingleton.java Normal file
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package com.baeldung.singleton;
import java.util.UUID;
import javax.inject.Singleton;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@Singleton
public class CarServiceSingleton {
private static Logger LOG = LoggerFactory.getLogger(CarServiceSingleton.class);
private UUID id = UUID.randomUUID();
private static int serviceQueue;
public UUID getId() {
return this.id;
}
@Override
public String toString() {
return "CarServiceSingleton [id=" + id + "]";
}
public int service(Car car) {
serviceQueue++;
LOG.info("Car {} is being serviced @ CarServiceSingleton - serviceQueue: {}", car, serviceQueue);
simulateService(car);
serviceQueue--;
LOG.info("Car service for {} is completed - serviceQueue: {}", car, serviceQueue);
return serviceQueue;
}
private void simulateService(Car car) {
try {
Thread.sleep(100);
car.setServiced(true);
} catch (InterruptedException e) {
LOG.error("CarServiceSingleton::InterruptedException: {}", e);
}
}
}

142
jee-7/src/test/java/com/baeldung/singleton/CarServiceIntegrationTest.java Normal file
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package com.baeldung.singleton;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
import javax.ejb.EJB;
import javax.inject.Inject;
import org.jboss.arquillian.container.test.api.Deployment;
import org.jboss.arquillian.junit.Arquillian;
import org.jboss.shrinkwrap.api.ShrinkWrap;
import org.jboss.shrinkwrap.api.asset.EmptyAsset;
import org.jboss.shrinkwrap.api.spec.JavaArchive;
import org.junit.Before;
import org.junit.FixMethodOrder;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.MethodSorters;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@RunWith(Arquillian.class)
@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class CarServiceIntegrationTest {
public static final Logger LOG = LoggerFactory.getLogger(CarServiceIntegrationTest.class);
@Deployment
public static JavaArchive createDeployment() {
return ShrinkWrap.create(JavaArchive.class)
.addClasses(CarServiceBean.class, CarServiceSingleton.class, CarServiceEjbSingleton.class, Car.class)
.addAsResource("META-INF/persistence.xml")
.addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml");
}
@Inject
private CarServiceBean carServiceBean;
@Inject
private CarServiceSingleton carServiceSingleton;
@EJB
private CarServiceEjbSingleton carServiceEjbSingleton;
private static Map<String, UUID> idMap = new HashMap<>();
@Before
public void setUp() {
// populate idMap only on first run
if (idMap.isEmpty()) {
LOG.info("setUp::carServiceBean: {}", carServiceBean.getId());
idMap.put("carServiceBeanId", carServiceBean.getId());
LOG.info("setUp::carServiceSingleton: {}", carServiceSingleton.getId());
idMap.put("carServiceSingletonId", carServiceSingleton.getId());
LOG.info("setUp::carServiceEjbSingleton: {}", carServiceEjbSingleton.getId());
idMap.put("carServiceEjbSingletonId", carServiceEjbSingleton.getId());
}
}
@Test
public void givenRun1_whenGetId_thenSingletonIdEqual() {
int testRun = 1;
assertNotNull(carServiceBean);
assertNotNull(carServiceSingleton);
assertNotNull(carServiceEjbSingleton);
UUID carServiceBeanId = carServiceBean.getId();
assertEquals(idMap.get("carServiceBeanId"), carServiceBeanId);
LOG.info("Test run {}::carServiceBeanId: {}", testRun, carServiceBeanId);
UUID carServiceSingletonId = carServiceSingleton.getId();
assertEquals(idMap.get("carServiceSingletonId"), carServiceSingletonId);
LOG.info("Test run {}::carServiceSingletonId: {}", testRun, carServiceSingletonId);
UUID carServiceEjbSingletonId = carServiceEjbSingleton.getId();
assertEquals(idMap.get("carServiceEjbSingletonId"), carServiceEjbSingletonId);
LOG.info("Test run {}::carServiceEjbSingletonId: {}", testRun, carServiceEjbSingletonId);
}
@Test
public void givenRun2_whenGetId_thenSingletonIdEqual() {
int testRun = 2;
assertNotNull(carServiceBean);
assertNotNull(carServiceSingleton);
assertNotNull(carServiceEjbSingleton);
UUID carServiceBeanId = carServiceBean.getId();
assertNotEquals(idMap.get("carServiceBeanId"), carServiceBeanId);
LOG.info("Test run {}::carServiceBeanId: {}", testRun, carServiceBeanId);
UUID carServiceSingletonId = carServiceSingleton.getId();
assertEquals(idMap.get("carServiceSingletonId"), carServiceSingletonId);
LOG.info("Test run {}::carServiceSingletonId: {}", testRun, carServiceSingletonId);
UUID carServiceEjbSingletonId = carServiceEjbSingleton.getId();
assertEquals(idMap.get("carServiceEjbSingletonId"), carServiceEjbSingletonId);
LOG.info("Test run {}::carServiceEjbSingletonId: {}", testRun, carServiceEjbSingletonId);
}
@Test
public void givenRun3_whenSingleton_thenNoLocking() {
for (int i = 0; i < 10; i++) {
new Thread(new Runnable() {
@Override
public void run() {
String model = Double.toString(Math.round(Math.random() * 100));
Car car = new Car("Speedster", model);
int serviceQueue = carServiceSingleton.service(car);
assertTrue(serviceQueue < 10);
}
}).start();
}
return;
}
@Test
public void givenRun4_whenEjb_thenLocking() {
for (int i = 0; i < 10; i++) {
new Thread(new Runnable() {
@Override
public void run() {
String model = Double.toString(Math.round(Math.random() * 100));
Car car = new Car("Speedster", model);
int serviceQueue = carServiceEjbSingleton.service(car);
assertEquals(0, serviceQueue);
}
}).start();
}
return;
}
}