BAEL-1592 (#3773)

* Injecting Prototype Beans into Singleton Instance

* removed final keywords from the test

spring-core/src/main/java/com/baeldung/scope/AppConfig.java

@@ -0,0 +1,43 @@
+package com.baeldung.scope;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import com.baeldung.scope.singletone.SingletonAppContextBean;
+import com.baeldung.scope.singletone.SingletonBean;
+import com.baeldung.scope.singletone.SingletonObjectFactoryBean;
+import com.baeldung.scope.singletone.SingletonProviderBean;
+import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Scope;
+
+@Configuration
+@ComponentScan("com.baeldung.scope")
+public class AppConfig {
+
+    @Bean
+    @Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
+    public PrototypeBean prototypeBean() {
+        return new PrototypeBean();
+    }
+
+    @Bean
+    public SingletonBean singletonBean() {
+        return new SingletonBean();
+    }
+
+    @Bean
+    public SingletonProviderBean singletonProviderBean() {
+        return new SingletonProviderBean();
+    }
+
+    @Bean
+    public SingletonAppContextBean singletonAppContextBean() {
+        return new SingletonAppContextBean();
+    }
+
+    @Bean
+    public SingletonObjectFactoryBean singletonObjectFactoryBean() {
+        return new SingletonObjectFactoryBean();
+    }
+}

spring-core/src/main/java/com/baeldung/scope/AppProxyScopeConfig.java

@@ -0,0 +1,22 @@
+package com.baeldung.scope;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import com.baeldung.scope.singletone.SingletonBean;
+import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.context.annotation.*;
+
+@Configuration
+@ComponentScan("com.baeldung.scope")
+public class AppProxyScopeConfig {
+
+    @Bean
+    @Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE, proxyMode = ScopedProxyMode.TARGET_CLASS)
+    public PrototypeBean prototypeBean() {
+        return new PrototypeBean();
+    }
+
+    @Bean
+    public SingletonBean singletonBean() {
+        return new SingletonBean();
+    }
+}

spring-core/src/main/java/com/baeldung/scope/BeanInjectionStarter.java

@@ -0,0 +1,22 @@
+package com.baeldung.scope;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import com.baeldung.scope.singletone.SingletonBean;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.util.Assert;
+
+public class BeanInjectionStarter {
+
+    public static void main(String[] args) throws InterruptedException {
+
+        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
+        SingletonBean firstSingleton = context.getBean(SingletonBean.class);
+        PrototypeBean firstPrototype = firstSingleton.getPrototypeBean();
+
+        SingletonBean secondSingleton = context.getBean(SingletonBean.class);
+        PrototypeBean secondPrototype = secondSingleton.getPrototypeBean();
+
+        Assert.isTrue(firstPrototype.equals(secondPrototype), "The same instance is returned");
+
+    }
+}

spring-core/src/main/java/com/baeldung/scope/prototype/PrototypeBean.java

@@ -0,0 +1,12 @@
+package com.baeldung.scope.prototype;
+
+import org.apache.log4j.Logger;
+
+public class PrototypeBean {
+
+    private final Logger logger = Logger.getLogger(this.getClass());
+
+    public PrototypeBean() {
+        logger.info("Prototype instance created");
+    }
+}

spring-core/src/main/java/com/baeldung/scope/singletone/SingletonAppContextBean.java

@@ -0,0 +1,20 @@
+package com.baeldung.scope.singletone;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import org.springframework.beans.BeansException;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+
+public class SingletonAppContextBean implements ApplicationContextAware {
+
+    private ApplicationContext applicationContext;
+
+    public PrototypeBean getPrototypeBean() {
+        return applicationContext.getBean(PrototypeBean.class);
+    }
+
+    @Override
+    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+        this.applicationContext = applicationContext;
+    }
+}

spring-core/src/main/java/com/baeldung/scope/singletone/SingletonBean.java

@@ -0,0 +1,24 @@
+package com.baeldung.scope.singletone;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import org.apache.log4j.Logger;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import java.time.LocalTime;
+
+public class SingletonBean {
+
+    private final Logger logger = Logger.getLogger(this.getClass());
+
+    @Autowired
+    private PrototypeBean prototypeBean;
+
+    public SingletonBean() {
+        logger.info("Singleton instance created");
+    }
+
+    public PrototypeBean getPrototypeBean() {
+        logger.info(String.valueOf(LocalTime.now()));
+        return prototypeBean;
+    }
+}

spring-core/src/main/java/com/baeldung/scope/singletone/SingletonLookupBean.java

@@ -0,0 +1,14 @@
+package com.baeldung.scope.singletone;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import org.springframework.beans.factory.annotation.Lookup;
+import org.springframework.stereotype.Component;
+
+@Component
+public class SingletonLookupBean {
+
+    @Lookup
+    public PrototypeBean getPrototypeBean() {
+        return null;
+    }
+}

spring-core/src/main/java/com/baeldung/scope/singletone/SingletonObjectFactoryBean.java

@@ -0,0 +1,15 @@
+package com.baeldung.scope.singletone;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import org.springframework.beans.factory.ObjectFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+
+public class SingletonObjectFactoryBean {
+
+    @Autowired
+    private ObjectFactory<PrototypeBean> prototypeBeanObjectFactory;
+
+    public PrototypeBean getPrototypeInstance() {
+        return prototypeBeanObjectFactory.getObject();
+    }
+}

spring-core/src/main/java/com/baeldung/scope/singletone/SingletonProviderBean.java

@@ -0,0 +1,16 @@
+package com.baeldung.scope.singletone;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import org.springframework.beans.factory.annotation.Autowired;
+
+import javax.inject.Provider;
+
+public class SingletonProviderBean {
+
+    @Autowired
+    private Provider<PrototypeBean> myPrototypeBeanProvider;
+
+    public PrototypeBean getPrototypeInstance() {
+        return myPrototypeBeanProvider.get();
+    }
+}

spring-core/src/test/java/com/baeldung/scope/PrototypeBeanInjectionTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.scope;
+
+import com.baeldung.scope.prototype.PrototypeBean;
+import com.baeldung.scope.singletone.SingletonLookupBean;
+import com.baeldung.scope.singletone.SingletonObjectFactoryBean;
+import com.baeldung.scope.singletone.SingletonProviderBean;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.support.AnnotationConfigContextLoader;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(loader = AnnotationConfigContextLoader.class, classes = AppConfig.class)
+public class PrototypeBeanInjectionTest {
+
+    @Test
+    public void givenPrototypeInjection_WhenObjectFactory_ThenNewInstanceReturn() {
+
+        AbstractApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
+
+        SingletonObjectFactoryBean firstContext = context.getBean(SingletonObjectFactoryBean.class);
+        SingletonObjectFactoryBean secondContext = context.getBean(SingletonObjectFactoryBean.class);
+
+        PrototypeBean firstInstance = firstContext.getPrototypeInstance();
+        PrototypeBean secondInstance = secondContext.getPrototypeInstance();
+
+        Assert.assertTrue("New instance expected", firstInstance != secondInstance);
+    }
+
+    @Test
+    public void givenPrototypeInjection_WhenLookup_ThenNewInstanceReturn() {
+
+        AbstractApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
+
+        SingletonLookupBean firstContext = context.getBean(SingletonLookupBean.class);
+        SingletonLookupBean secondContext = context.getBean(SingletonLookupBean.class);
+
+        PrototypeBean firstInstance = firstContext.getPrototypeBean();
+        PrototypeBean secondInstance = secondContext.getPrototypeBean();
+
+        Assert.assertTrue("New instance expected", firstInstance != secondInstance);
+    }
+
+    @Test
+    public void givenPrototypeInjection_WhenProvider_ThenNewInstanceReturn() {
+
+        AbstractApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
+
+        SingletonProviderBean firstContext = context.getBean(SingletonProviderBean.class);
+        SingletonProviderBean secondContext = context.getBean(SingletonProviderBean.class);
+
+        PrototypeBean firstInstance = firstContext.getPrototypeInstance();
+        PrototypeBean secondInstance = secondContext.getPrototypeInstance();
+
+        Assert.assertTrue("New instance expected", firstInstance != secondInstance);
+    }
+}