Added code for https://jstobigdata.com/spring/dependency-injection-autowired-resource-and-inject/

Author: Bikraji

spring-core-ioc/pom.xml

@@ -23,10 +23,37 @@
       <artifactId>spring-context</artifactId>
     </dependency>
 
+    <!-- JSR 330 -->
+   <dependency>
+      <groupId>javax.inject</groupId>
+      <artifactId>javax.inject</artifactId>
+      <version>1</version>
+    </dependency>
+
+    <!-- JSR 250 -->
+    <dependency>
+      <groupId>javax.annotation</groupId>
+      <artifactId>javax.annotation-api</artifactId>
+    </dependency>
+
     <dependency>
       <groupId>org.junit.jupiter</groupId>
       <artifactId>junit-jupiter-api</artifactId>
+      <scope>test</scope>
     </dependency>
+
+    <dependency>
+      <groupId>org.junit.platform</groupId>
+      <artifactId>junit-platform-runner</artifactId>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.springframework</groupId>
+      <artifactId>spring-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+
   </dependencies>
 
 

spring-core-ioc/src/main/java/basic/ioc/wiring/ConfigWiring.java

@@ -0,0 +1,10 @@
+package basic.ioc.wiring;
+
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+@ComponentScan("basic.ioc.wiring")
+@Configuration
+public class ConfigWiring {
+  //extra configs goes here
+}

spring-core-ioc/src/main/java/basic/ioc/wiring/FileReader.java

@@ -0,0 +1,7 @@
+package basic.ioc.wiring;
+
+public abstract class FileReader {
+  public void print() {
+    System.out.println("Inside FileReader");
+  }
+}

spring-core-ioc/src/main/java/basic/ioc/wiring/PdfFileReader.java

@@ -0,0 +1,12 @@
+package basic.ioc.wiring;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class PdfFileReader extends FileReader {
+
+  @Override
+  public void print() {
+    System.out.println("Inside PdfFileReader");
+  }
+}

spring-core-ioc/src/main/java/basic/ioc/wiring/WordFileReader.java

@@ -0,0 +1,12 @@
+package basic.ioc.wiring;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class WordFileReader extends FileReader {
+
+  @Override
+  public void print() {
+    System.out.println("Inside WordFileReader");
+  }
+}

spring-core-ioc/src/test/java/basic/ioc/wiring/AutowiredTest.java

@@ -0,0 +1,43 @@
+package basic.ioc.wiring;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig(ConfigWiring.class)
+public class AutowiredTest {
+
+  //Inject by Type
+  @Autowired
+  private PdfFileReader pdfFileReader;
+
+  @Test
+  public void injectByType() {
+    Assert.assertNotNull(pdfFileReader);
+    Assert.assertEquals(pdfFileReader.getClass(), PdfFileReader.class);
+  }
+
+  //Inject by @Qualifier
+  @Autowired
+  @Qualifier("wordFileReader")
+  private FileReader fileReader;
+
+  @Test
+  public void injectByQualifier() {
+    Assert.assertNotNull(fileReader);
+    Assert.assertEquals(fileReader.getClass(), WordFileReader.class);
+  }
+
+  //Inject by Field name
+  @Autowired
+  private FileReader wordFileReader;
+
+  @Test
+  public void injectByFieldName() {
+    Assert.assertNotNull(wordFileReader);
+    Assert.assertEquals(wordFileReader.getClass(), WordFileReader.class);
+  }
+
+}

spring-core-ioc/src/test/java/basic/ioc/wiring/InjectTest.java

@@ -0,0 +1,68 @@
+package basic.ioc.wiring;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+import javax.inject.Inject;
+import javax.inject.Named;
+
+@SpringJUnitConfig(ConfigWiring.class)
+public class InjectTest {
+
+  //Inject by Type
+  @Inject
+  private PdfFileReader fileReader;
+
+  @Test
+  public void injectByType() {
+    Assert.assertNotNull(fileReader);
+    Assert.assertEquals(fileReader.getClass(), PdfFileReader.class);
+  }
+
+  //Inject by @Qualifier
+  @Inject
+  @Qualifier("wordFileReader")
+  private FileReader fileReader3;
+
+  @Test
+  public void injectByQualifier() {
+    Assert.assertNotNull(fileReader3);
+    Assert.assertEquals(fileReader3.getClass(), WordFileReader.class);
+  }
+
+  //Inject by name with @Named annotation
+  @Inject
+  @Named("pdfFileReader")
+  private FileReader fileReader2;
+
+  @Test
+  public void injectByName() {
+    Assert.assertNotNull(fileReader2);
+    Assert.assertEquals(fileReader2.getClass(), PdfFileReader.class);
+  }
+
+  //Inject by field Name
+  @Inject
+  private FileReader wordFileReader;
+
+  @Test
+  public void injectByName2() {
+    Assert.assertNotNull(wordFileReader);
+    Assert.assertEquals(wordFileReader.getClass(), WordFileReader.class);
+  }
+
+  //Check precedence - Don't do this
+  //TODO - Uncomment the below line and check what happens
+  /*@Inject
+  @Qualifier("pdfFileReader")
+  @Named("wordFileReader")
+  private FileReader pdfFileReader;
+
+  @Test
+  public void checkPrecedence() {
+    Assert.assertNotNull(pdfFileReader);
+    Assert.assertEquals(pdfFileReader.getClass(), PdfFileReader.class);
+  }*/
+}

spring-core-ioc/src/test/java/basic/ioc/wiring/ResourceTest.java

@@ -0,0 +1,67 @@
+package basic.ioc.wiring;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+import javax.annotation.Resource;
+
+@SpringJUnitConfig(ConfigWiring.class)
+public class ResourceTest {
+
+  //Uncomment and show the exception that gets reproduced
+  //@Resource
+  //private FileReader fReader;
+
+  //Resolve by property name
+  @Resource
+  private FileReader pdfFileReader;
+
+  @Test
+  public void resolveByPropertyName() {
+    Assert.assertNotNull(pdfFileReader);
+    Assert.assertEquals(pdfFileReader.getClass(), PdfFileReader.class);
+  }
+
+  //Resolve by explicit name
+  @Resource(name = "wordFileReader")
+  private FileReader reader;
+
+  @Test
+  public void resolveByExplicitName() {
+    Assert.assertNotNull(reader);
+    Assert.assertEquals(reader.getClass(), WordFileReader.class);
+  }
+
+  //Resolve by type auto detection
+  @Resource
+  private WordFileReader fileReader;
+
+  @Test
+  public void resolveByAutoType(){
+    Assert.assertNotNull(fileReader);
+    Assert.assertEquals(fileReader.getClass(), WordFileReader.class);
+  }
+
+  //Resolve by explicit Type
+  @Resource(type = PdfFileReader.class)
+  private FileReader fileReader2;
+
+  @Test
+  public void resolveByExplicitType() {
+    Assert.assertNotNull(fileReader2);
+    Assert.assertEquals(fileReader2.getClass(), PdfFileReader.class);
+  }
+
+  //Resolve by Qualifier
+  @Qualifier("pdfFileReader")
+  @Resource
+  private FileReader myFileReader;
+
+  @Test
+  public void resolveByQualifier(){
+    Assert.assertNotNull(myFileReader);
+    Assert.assertEquals(myFileReader.getClass(), PdfFileReader.class);
+  }
+}