evaluation article, different types of bean injection. (#3511)

* Different types of bean injection in spring, initial write-up

* Evaluation article code example, different types of bean injection.

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/Student.java

@@ -0,0 +1,21 @@
+package com.baeldung.dependencyinjectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Student {
+
+	private TeacherFinder teacherFinder;
+
+	@Autowired
+	public Student(TeacherFinder teacherFinder) {
+		this.teacherFinder = teacherFinder;
+	}
+
+	public String getTeacher() {
+        return teacherFinder.getTeacherFinder();
+    }
+	// business logic that actually uses the injected teacherFinders is omitted...
+}
+

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/Student2.java

@@ -0,0 +1,20 @@
+package com.baeldung.dependencyinjectiontypes;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class Student2 {
+
+	private TeacherFinder teacherFinder;
+
+	@Autowired
+    public void setTeacherFinder(TeacherFinder teacherFinder) {
+        this.teacherFinder = teacherFinder;
+    }
+	
+	public String getTeacher() {
+        return teacherFinder.getTeacherFinder();
+    }
+
+}

spring-core/src/main/java/com/baeldung/dependencyinjectiontypes/TeacherFinder.java

@@ -0,0 +1,16 @@
+package com.baeldung.dependencyinjectiontypes;
+public class TeacherFinder {
+
+    private String teacherFinder;
+
+	public String getTeacherFinder() {
+		return teacherFinder;
+	}
+
+	public void setTeacherFinder(String teacherFinder) {
+		this.teacherFinder = teacherFinder;
+	}
+
+   
+}
+

spring-core/src/main/java/com/baeldung/setterdi/Config.java

@@ -1,35 +1,58 @@
-package com.baeldung.setterdi;
+package com.baeldung.setterdi;
-
+
-import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.ComponentScan;
-import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Configuration;
-
+
-import com.baeldung.setterdi.domain.Engine;
+import com.baeldung.dependencyinjectiontypes.Student;
-import com.baeldung.setterdi.domain.Trailer;
+import com.baeldung.dependencyinjectiontypes.Student2;
-import com.baeldung.setterdi.domain.Transmission;
+import com.baeldung.dependencyinjectiontypes.TeacherFinder;
-
+import com.baeldung.setterdi.domain.Engine;
-@Configuration
+import com.baeldung.setterdi.domain.Trailer;
-@ComponentScan("com.baeldung.setterdi")
+import com.baeldung.setterdi.domain.Transmission;
-public class Config {
+
-
+@Configuration
-    @Bean
+@ComponentScan("com.baeldung.setterdi")
-    public Engine engine() {
+public class Config {
-        Engine engine = new Engine();
+
-        engine.setType("v8");
+    @Bean
-        engine.setVolume(5);
+    public Engine engine() {
-        return engine;
+        Engine engine = new Engine();
-    }
+        engine.setType("v8");
-
+        engine.setVolume(5);
-    @Bean
+        return engine;
-    public Transmission transmission() {
+    }
-        Transmission transmission = new Transmission();
+
-        transmission.setType("sliding");
+    @Bean
-        return transmission;
+    public Transmission transmission() {
-    }
+        Transmission transmission = new Transmission();
-
+        transmission.setType("sliding");
-    @Bean
+        return transmission;
-    public Trailer trailer() {
+    }
-        Trailer trailer = new Trailer();
+
-        return trailer;
+    @Bean
-    }
+    public Trailer trailer() {
+        Trailer trailer = new Trailer();
+        return trailer;
+    }
+    
+    @Bean 
+    public TeacherFinder teacherFinder(){
+    	TeacherFinder teacherFinder =new TeacherFinder();
+    	teacherFinder.setTeacherFinder("author");
+    	return teacherFinder;
+    }
+    
+    @Bean
+    public Student student() {
+        return new Student(teacherFinder());
+    }
+ 
+    @Bean
+    public Student2 student2() {
+    	Student2 student2 = new Student2();
+    	student2.setTeacherFinder(teacherFinder());
+        return student2;
+    }
+ 
 }

spring-core/src/test/java/com/baeldung/dependencyinjectiontypes/DependencyInjectionTest.java

@@ -2,13 +2,25 @@ package com.baeldung.dependencyinjectiontypes;
 
 import static org.junit.Assert.assertTrue;
 
+import org.apache.log4j.Logger;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationContext;
-import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.support.AnnotationConfigContextLoader;
 
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes=com.baeldung.setterdi.Config.class, loader=AnnotationConfigContextLoader.class)
 public class DependencyInjectionTest {
+	
+	@Autowired
+	private ApplicationContext appContext;
+	
+	Logger logger = Logger.getLogger(this.getClass());
 
-    @Test
+   /* @Test
     public void givenAutowiredAnnotation_WhenSetOnSetter_ThenDependencyValid() {
         
     	ApplicationContext context = new ClassPathXmlApplicationContext("dependencyinjectiontypes-context.xml");
@@ -30,6 +42,20 @@ public class DependencyInjectionTest {
     	String formattedArticle = article.format(originalText);
     	
     	assertTrue(originalText.toUpperCase().equals(formattedArticle));
+    }*/
+    
+    @Test
+    public void givenAutowiredAnnotation_OnSetter_ThenDependencyValid() {
+    	Student student = (Student) appContext.getBean("student");
+    	String teacherFound = student.getTeacher();
+    	assertTrue(teacherFound.equals("author"));
+    }
+    
+    @Test
+    public void givenAutowiredAnnotation_OnConstructor_ThenDependencyValid() {
+    	Student2 student2 = (Student2) appContext.getBean("student2");
+    	String teacherFound = student2.getTeacher();
+    	assertTrue(teacherFound.equals("author"));
     }
     
 }