Merge pull request #848 from DianeDuan/spring-factorybean

BAEL-453: How to use the Spring FactoryBean

spring-core/pom.xml

@@ -47,6 +47,11 @@
             <version>4.12</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>20.0</version>
+        </dependency>
     </dependencies>
 
     <build>

spring-core/src/main/java/com/baeldung/factorybean/FactoryBeanAppConfig.java

@@ -0,0 +1,25 @@
+package com.baeldung.factorybean;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class FactoryBeanAppConfig {
+    @Bean
+    public ToolFactory tool() {
+        ToolFactory factory = new ToolFactory();
+        factory.setFactoryId(7070);
+        factory.setToolId(2);
+        factory.setToolName("wrench");
+        factory.setToolPrice(3.7);
+        return factory;
+    }
+
+    @Bean
+    public Worker worker() throws Exception {
+        Worker worker = new Worker();
+        worker.setNumber("1002");
+        worker.setTool(tool().getObject());
+        return worker;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/InitializationToolFactory.java

@@ -0,0 +1,67 @@
+package com.baeldung.factorybean;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.util.StringUtils;
+
+public class InitializationToolFactory implements FactoryBean<Tool>, InitializingBean {
+    private int factoryId;
+    private int toolId;
+    private String toolName;
+    private double toolPrice;
+
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        checkArgument(!StringUtils.isEmpty(toolName), "tool name cannot be empty");
+        checkArgument(toolPrice >= 0, "tool price should not be less than 0");
+    }
+
+    @Override
+    public Tool getObject() throws Exception {
+        return new Tool(toolId, toolName, toolPrice);
+    }
+
+    @Override
+    public Class<?> getObjectType() {
+        return Tool.class;
+    }
+
+    @Override
+    public boolean isSingleton() {
+        return false;
+    }
+
+    public int getFactoryId() {
+        return factoryId;
+    }
+
+    public void setFactoryId(int factoryId) {
+        this.factoryId = factoryId;
+    }
+
+    public int getToolId() {
+        return toolId;
+    }
+
+    public void setToolId(int toolId) {
+        this.toolId = toolId;
+    }
+
+    public String getToolName() {
+        return toolName;
+    }
+
+    public void setToolName(String toolName) {
+        this.toolName = toolName;
+    }
+
+    public double getToolPrice() {
+        return toolPrice;
+    }
+
+    public void setToolPrice(double toolPrice) {
+        this.toolPrice = toolPrice;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/NonSingleToolFactory.java

@@ -0,0 +1,56 @@
+package com.baeldung.factorybean;
+
+import org.springframework.beans.factory.config.AbstractFactoryBean;
+
+public class NonSingleToolFactory extends AbstractFactoryBean<Tool> {
+    private int factoryId;
+    private int toolId;
+    private String toolName;
+    private double toolPrice;
+
+    public NonSingleToolFactory() {
+        setSingleton(false);
+    }
+
+    @Override
+    public Class<?> getObjectType() {
+        return Tool.class;
+    }
+
+    @Override
+    protected Tool createInstance() throws Exception {
+        return new Tool(toolId, toolName, toolPrice);
+    }
+
+    public int getFactoryId() {
+        return factoryId;
+    }
+
+    public void setFactoryId(int factoryId) {
+        this.factoryId = factoryId;
+    }
+
+    public int getToolId() {
+        return toolId;
+    }
+
+    public void setToolId(int toolId) {
+        this.toolId = toolId;
+    }
+
+    public String getToolName() {
+        return toolName;
+    }
+
+    public void setToolName(String toolName) {
+        this.toolName = toolName;
+    }
+
+    public double getToolPrice() {
+        return toolPrice;
+    }
+
+    public void setToolPrice(double toolPrice) {
+        this.toolPrice = toolPrice;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/PostConstructToolFactory.java

@@ -0,0 +1,68 @@
+package com.baeldung.factorybean;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import javax.annotation.PostConstruct;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.util.StringUtils;
+
+public class PostConstructToolFactory implements FactoryBean<Tool> {
+    private int factoryId;
+    private int toolId;
+    private String toolName;
+    private double toolPrice;
+
+    @Override
+    public Tool getObject() throws Exception {
+        return new Tool(toolId, toolName, toolPrice);
+    }
+
+    @Override
+    public Class<?> getObjectType() {
+        return Tool.class;
+    }
+
+    @Override
+    public boolean isSingleton() {
+        return false;
+    }
+
+    @PostConstruct
+    public void checkParams() {
+        checkArgument(!StringUtils.isEmpty(toolName), "tool name cannot be empty");
+        checkArgument(toolPrice >= 0, "tool price should not be less than 0");
+    }
+
+    public int getFactoryId() {
+        return factoryId;
+    }
+
+    public void setFactoryId(int factoryId) {
+        this.factoryId = factoryId;
+    }
+
+    public int getToolId() {
+        return toolId;
+    }
+
+    public void setToolId(int toolId) {
+        this.toolId = toolId;
+    }
+
+    public String getToolName() {
+        return toolName;
+    }
+
+    public void setToolName(String toolName) {
+        this.toolName = toolName;
+    }
+
+    public double getToolPrice() {
+        return toolPrice;
+    }
+
+    public void setToolPrice(double toolPrice) {
+        this.toolPrice = toolPrice;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/SingleToolFactory.java

@@ -0,0 +1,53 @@
+package com.baeldung.factorybean;
+
+import org.springframework.beans.factory.config.AbstractFactoryBean;
+
+//no need to set singleton property because default value is true
+public class SingleToolFactory extends AbstractFactoryBean<Tool> {
+    private int factoryId;
+    private int toolId;
+    private String toolName;
+    private double toolPrice;
+
+    @Override
+    public Class<?> getObjectType() {
+        return Tool.class;
+    }
+
+    @Override
+    protected Tool createInstance() throws Exception {
+        return new Tool(toolId, toolName, toolPrice);
+    }
+
+    public int getFactoryId() {
+        return factoryId;
+    }
+
+    public void setFactoryId(int factoryId) {
+        this.factoryId = factoryId;
+    }
+
+    public int getToolId() {
+        return toolId;
+    }
+
+    public void setToolId(int toolId) {
+        this.toolId = toolId;
+    }
+
+    public String getToolName() {
+        return toolName;
+    }
+
+    public void setToolName(String toolName) {
+        this.toolName = toolName;
+    }
+
+    public double getToolPrice() {
+        return toolPrice;
+    }
+
+    public void setToolPrice(double toolPrice) {
+        this.toolPrice = toolPrice;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/Tool.java

@@ -0,0 +1,40 @@
+package com.baeldung.factorybean;
+
+public class Tool {
+    private int id;
+    private String name;
+    private double price;
+
+    public Tool() {
+    }
+
+    public Tool(int id, String name, double price) {
+        this.id = id;
+        this.name = name;
+        this.price = price;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    public void setPrice(double price) {
+        this.price = price;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/ToolFactory.java

@@ -0,0 +1,57 @@
+package com.baeldung.factorybean;
+
+import org.springframework.beans.factory.FactoryBean;
+
+public class ToolFactory implements FactoryBean<Tool> {
+    private int factoryId;
+    private int toolId;
+    private String toolName;
+    private double toolPrice;
+
+    @Override
+    public Tool getObject() throws Exception {
+        return new Tool(toolId, toolName, toolPrice);
+    }
+
+    @Override
+    public Class<?> getObjectType() {
+        return Tool.class;
+    }
+
+    @Override
+    public boolean isSingleton() {
+        return false;
+    }
+
+    public int getFactoryId() {
+        return factoryId;
+    }
+
+    public void setFactoryId(int factoryId) {
+        this.factoryId = factoryId;
+    }
+
+    public int getToolId() {
+        return toolId;
+    }
+
+    public void setToolId(int toolId) {
+        this.toolId = toolId;
+    }
+
+    public String getToolName() {
+        return toolName;
+    }
+
+    public void setToolName(String toolName) {
+        this.toolName = toolName;
+    }
+
+    public double getToolPrice() {
+        return toolPrice;
+    }
+
+    public void setToolPrice(double toolPrice) {
+        this.toolPrice = toolPrice;
+    }
+}

spring-core/src/main/java/com/baeldung/factorybean/Worker.java

@@ -0,0 +1,30 @@
+package com.baeldung.factorybean;
+
+public class Worker {
+    private String number;
+    private Tool tool;
+
+    public Worker() {
+    }
+
+    public Worker(String number, Tool tool) {
+        this.number = number;
+        this.tool = tool;
+    }
+
+    public String getNumber() {
+        return number;
+    }
+
+    public void setNumber(String number) {
+        this.number = number;
+    }
+
+    public Tool getTool() {
+        return tool;
+    }
+
+    public void setTool(Tool tool) {
+        this.tool = tool;
+    }
+}

spring-core/src/main/resources/factorybean-abstract-spring-ctx.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="http://www.springframework.org/schema/beans"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+    <bean id="singleTool" class="com.baeldung.factorybean.SingleToolFactory">
+        <property name="factoryId" value="3001"/>
+        <property name="toolId" value="1"/>
+        <property name="toolName" value="screwdriver"/>
+        <property name="toolPrice" value="1.5"/>
+    </bean>
+
+    <bean id="nonSingleTool" class="com.baeldung.factorybean.NonSingleToolFactory">
+        <property name="factoryId" value="3002"/>
+        <property name="toolId" value="2"/>
+        <property name="toolName" value="screwdriver"/>
+        <property name="toolPrice" value="1.5"/>
+    </bean>
+
+    <bean id="worker1" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="50001"/>
+        <property name="tool" ref="singleTool"/>
+    </bean>
+
+    <bean id="worker2" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="50002"/>
+        <property name="tool" ref="singleTool"/>
+    </bean>
+
+    <bean id="worker3" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="50003"/>
+        <property name="tool" ref="nonSingleTool"/>
+    </bean>
+
+    <bean id="worker4" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="50004"/>
+        <property name="tool" ref="nonSingleTool"/>
+    </bean>
+</beans>

spring-core/src/main/resources/factorybean-init-spring-ctx.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="http://www.springframework.org/schema/beans"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+    <bean id="initializationTool" class="com.baeldung.factorybean.InitializationToolFactory">
+        <property name="factoryId" value="1010"/>
+        <property name="toolId" value="1"/>
+        <property name="toolName" value="screwdriver"/>
+        <property name="toolPrice" value="-1"/>
+    </bean>
+
+    <bean id="worker" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="36"/>
+        <property name="tool" ref="initializationTool"/>
+    </bean>
+</beans>

spring-core/src/main/resources/factorybean-postconstruct-spring-ctx.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns:context="http://www.springframework.org/schema/context"
+       xmlns="http://www.springframework.org/schema/beans"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
+
+    <context:annotation-config/>
+
+    <bean id="postConstructTool" class="com.baeldung.factorybean.PostConstructToolFactory">
+        <property name="factoryId" value="2020"/>
+        <property name="toolId" value="1"/>
+        <property name="toolName" value=""/>
+        <property name="toolPrice" value="2.2"/>
+    </bean>
+
+    <bean id="worker" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="37"/>
+        <property name="tool" ref="postConstructTool"/>
+    </bean>
+</beans>

spring-core/src/main/resources/factorybean-spring-ctx.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="http://www.springframework.org/schema/beans"
+       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
+
+    <bean id="tool" class="com.baeldung.factorybean.ToolFactory">
+        <property name="factoryId" value="9090"/>
+        <property name="toolId" value="1"/>
+        <property name="toolName" value="screwdriver"/>
+        <property name="toolPrice" value="1.5"/>
+    </bean>
+
+    <bean id="worker" class="com.baeldung.factorybean.Worker">
+        <property name="number" value="1001"/>
+        <property name="tool" ref="tool"/>
+    </bean>
+</beans>

spring-core/src/test/java/com/baeldung/factorybean/AbstractFactoryBeanTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.factorybean;
+
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+public class AbstractFactoryBeanTest {
+    @Test
+    public void testSingleToolFactory() {
+        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:factorybean-abstract-spring-ctx.xml");
+
+        Worker worker1 = (Worker) context.getBean("worker1");
+        Worker worker2 = (Worker) context.getBean("worker2");
+
+        assertThat(worker1.getNumber(), equalTo("50001"));
+        assertThat(worker2.getNumber(), equalTo("50002"));
+        assertTrue(worker1.getTool() == worker2.getTool());
+    }
+
+    @Test
+    public void testNonSingleToolFactory() {
+        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:factorybean-abstract-spring-ctx.xml");
+
+        Worker worker3 = (Worker) context.getBean("worker3");
+        Worker worker4 = (Worker) context.getBean("worker4");
+
+        assertThat(worker3.getNumber(), equalTo("50003"));
+        assertThat(worker4.getNumber(), equalTo("50004"));
+        assertTrue(worker3.getTool() != worker4.getTool());
+    }
+}

spring-core/src/test/java/com/baeldung/factorybean/FactoryBeanInitializeTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.factorybean;
+
+import org.junit.Test;
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+public class FactoryBeanInitializeTest {
+    @Test(expected = BeanCreationException.class)
+    public void testInitializationToolFactory() {
+        new ClassPathXmlApplicationContext("classpath:factorybean-init-spring-ctx.xml");
+    }
+
+    @Test(expected = BeanCreationException.class)
+    public void testPostConstructToolFactory() {
+        new ClassPathXmlApplicationContext("classpath:factorybean-postconstruct-spring-ctx.xml");
+    }
+}

spring-core/src/test/java/com/baeldung/factorybean/FactoryBeanTest.java

@@ -0,0 +1,39 @@
+package com.baeldung.factorybean;
+
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.junit.Assert.assertThat;
+
+import org.junit.Test;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+public class FactoryBeanTest {
+    @Test
+    public void testConstructWorkerByXml() {
+        ApplicationContext context = new ClassPathXmlApplicationContext("classpath:factorybean-spring-ctx.xml");
+
+        Worker worker = (Worker) context.getBean("worker");
+        assertThat(worker.getNumber(), equalTo("1001"));
+        assertThat(worker.getTool().getId(), equalTo(1));
+        assertThat(worker.getTool().getName(), equalTo("screwdriver"));
+        assertThat(worker.getTool().getPrice(), equalTo(1.5));
+
+        ToolFactory toolFactory = (ToolFactory) context.getBean("&tool");
+        assertThat(toolFactory.getFactoryId(), equalTo(9090));
+    }
+
+    @Test
+    public void testConstructWorkerByJava() {
+        ApplicationContext context = new AnnotationConfigApplicationContext(FactoryBeanAppConfig.class);
+
+        Worker worker = (Worker) context.getBean("worker");
+        assertThat(worker.getNumber(), equalTo("1002"));
+        assertThat(worker.getTool().getId(), equalTo(2));
+        assertThat(worker.getTool().getName(), equalTo("wrench"));
+        assertThat(worker.getTool().getPrice(), equalTo(3.7));
+
+        ToolFactory toolFactory = (ToolFactory) context.getBean("&tool");
+        assertThat(toolFactory.getFactoryId(), equalTo(7070));
+    }
+}