Difference between CDI and EJB singleton (#6915)

* Singleton injection examples and tests added * code and tests implemented
2019-05-08 16:40:54 +02:00
parent 57ec69ad3b
commit 8209ec4a1f
5 changed files with 286 additions and 0 deletions
@@ -0,0 +1,142 @@
+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;
+    }
+
+}