Evaluation article about types of bean injection in spring

spring-core/src/main/java/com/baelding/injectiontypes/BeanDefinition.java

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+package com.baelding.injectiontypes;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class BeanDefinition {
+
+    @Bean
+    public UsefulBean usefulBean() {
+        UsefulBean usefulBean = new UsefulBean("Hello", "Injection");
+        return usefulBean;
+    }
+
+}

spring-core/src/main/java/com/baelding/injectiontypes/ConstructorInjection.java

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+package com.baelding.injectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class ConstructorInjection {
+
+    private UsefulBean usefulBean;
+
+    @Autowired
+    public ConstructorInjection(UsefulBean usefulBean) {
+        this.usefulBean = usefulBean;
+    }
+
+    public String getParameters() {
+        return "Using constructor injection, we got these parameters " + usefulBean.getParameters();
+    }
+
+}

spring-core/src/main/java/com/baelding/injectiontypes/FieldInjection.java

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+package com.baelding.injectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class FieldInjection {
+
+    @Autowired
+    private UsefulBean usefulBean;
+    
+    public String getParameters() {
+        return "Using field injection, we got these parameters " + usefulBean.getParameters();
+    }
+
+}

spring-core/src/main/java/com/baelding/injectiontypes/SetterInjection.java

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+package com.baelding.injectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class SetterInjection {
+    
+    private UsefulBean usefulBean;
+    
+    @Autowired
+    public void setUsefulBean(UsefulBean usefulBean) {
+        this.usefulBean = usefulBean;
+    }
+    
+    public String getParameters() {
+        return "Using setter injection, we got these parameters " + usefulBean.getParameters();
+    }
+    
+}

spring-core/src/main/java/com/baelding/injectiontypes/UsefulBean.java

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+package com.baelding.injectiontypes;
+
+public class UsefulBean {
+
+    private String firstParameter;
+    private String secondParameter;
+
+    public UsefulBean(String firstParameter, String secondParameter) {
+        this.firstParameter = firstParameter;
+        this.secondParameter = secondParameter;
+    }
+
+    public String getParameters() {
+        return firstParameter + "-" + secondParameter;
+    }
+
+}

spring-core/src/test/java/com/baeldung/injectiontypes/TypesOfInjectionTest.java

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+package com.baeldung.injectiontypes;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.support.AnnotationConfigContextLoader;
+
+import com.baelding.injectiontypes.BeanDefinition;
+import com.baelding.injectiontypes.ConstructorInjection;
+import com.baelding.injectiontypes.FieldInjection;
+import com.baelding.injectiontypes.SetterInjection;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(
+  loader = AnnotationConfigContextLoader.class,
+  classes = {BeanDefinition.class, ConstructorInjection.class, SetterInjection.class, FieldInjection.class})
+public class TypesOfInjectionTest {
+    
+    @Autowired
+    private ConstructorInjection constructorInjection;
+    
+    @Autowired
+    private FieldInjection fieldInjection;
+    
+    @Autowired
+    private SetterInjection setterInjection;
+    
+    @Test
+    public void givenWiredDependencies_WhenExecutingGetBean_ThenDependenciesShouldBeAlreadyInjected() {
+        assertEquals("Using constructor injection, we got these parameters Hello-Injection",constructorInjection.getParameters());
+        assertEquals("Using field injection, we got these parameters Hello-Injection",fieldInjection.getParameters());
+        assertEquals("Using setter injection, we got these parameters Hello-Injection",setterInjection.getParameters());
+    }
+
+}