basics of spring autowire - first cut

spring-autowire/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.baeldung</groupId>
+  <artifactId>spring-autowire</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <name>spring-autowire</name>
+  <url>http://maven.apache.org</url>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <org.springframework.version>4.2.5.RELEASE</org.springframework.version>
+    <maven-compiler-plugin.version>3.5.1</maven-compiler-plugin.version>
+    <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
+  </properties>
+
+  <dependencies>
+  	<dependency>
+	    <groupId>junit</groupId>
+	    <artifactId>junit</artifactId>
+	    <version>4.11</version>
+	</dependency>
+    <dependency>
+	  <groupId>org.springframework</groupId>
+	  <artifactId>spring-core</artifactId>
+	  <version>${org.springframework.version}</version>
+	</dependency>
+	<dependency>
+	  <groupId>org.springframework</groupId>
+	  <artifactId>spring-context</artifactId>
+	  <version>${org.springframework.version}</version>
+	</dependency>
+	<dependency>
+        <groupId>org.springframework</groupId>
+        <artifactId>spring-test</artifactId>
+        <version>${org.springframework.version}</version>
+        <scope>test</scope>
+    </dependency>
+  </dependencies>
+  
+  <build>
+        <finalName>spring-autowire</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${maven-surefire-plugin.version}</version>
+            </plugin>
+        </plugins>
+    </build>  
+</project>

spring-autowire/src/main/java/com/baeldung/autowire/sample/App.java

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+package com.baeldung.autowire.sample;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+
+public class App {
+	public static void main(String[] args) {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
+		FooService fooService = ctx.getBean(FooService.class);
+		fooService.doStuff();
+	}
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/AppConfig.java

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+package com.baeldung.autowire.sample;
+
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ComponentScan("com.baeldung.autowire.sample")
+public class AppConfig {
+
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/Bar.java

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+package com.baeldung.autowire.sample;
+
+public class Bar {
+
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/BarFormatter.java

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+package com.baeldung.autowire.sample;
+
+import org.springframework.stereotype.Component;
+
+@FormatterType("Bar")
+@Component
+public class BarFormatter implements Formatter {
+
+    public String format() {
+        return "bar";
+    }
+    
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/Foo.java

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+package com.baeldung.autowire.sample;
+
+public class Foo {
+
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/FooDAO.java

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+package com.baeldung.autowire.sample;
+
+public class FooDAO {
+
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/FooFormatter.java

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+package com.baeldung.autowire.sample;
+
+import org.springframework.stereotype.Component;
+
+@FormatterType("Foo")
+@Component
+public class FooFormatter implements Formatter {
+
+    public String format() {
+        return "foo";
+    }
+    
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/FooService.java

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+package com.baeldung.autowire.sample;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class FooService {
+    
+    @Autowired
+    @FormatterType("Foo")
+    private Formatter formatter;
+    
+    public String doStuff(){
+        return formatter.format();
+    }
+    
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/Formatter.java

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+package com.baeldung.autowire.sample;
+
+public interface Formatter {
+
+	String format();
+
+}

spring-autowire/src/main/java/com/baeldung/autowire/sample/FormatterType.java

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+package com.baeldung.autowire.sample;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.springframework.beans.factory.annotation.Qualifier;
+
+@Qualifier
+@Target({ElementType.FIELD, ElementType.METHOD,ElementType.TYPE, ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface FormatterType {
+    
+    String value();
+
+}

spring-autowire/src/test/java/com/baeldung/autowire/sample/FooServiceTest.java

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+package com.baeldung.autowire.sample;
+
+import org.junit.Assert;
+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;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes=AppConfig.class, loader=AnnotationConfigContextLoader.class)
+public class FooServiceTest {
+    
+    @Autowired
+    FooService fooService;
+    
+    @Test
+    public void whenFooFormatterType_thenReturnFoo(){
+        Assert.assertEquals("foo", fooService.doStuff());
+    }
+}