Autowiring using XML Configuration with "Autowiring Mode : no"

• Definition : In this mode, no autowiring is performed. Dependencies must be explicitly defined using <property> or <constructor-arg> tags.
• Example :

  <bean id="engine" class="com.example.Engine" />
  <bean id="car" class="com.example.Car">
      <property name="engine" ref="engine" />
  </bean>

• Explanation : Here, no autowiring is used. The dependency (engine) is explicitly provided using the <property> tag. Spring will not attempt to inject dependencies automatically.
• Internal Behavior : In this mode, no automatic injection is performed. All dependencies must be explicitly defined using <property> or <constructor-arg> tags in the XML configuration. Spring does not attempt to inject anything by itself.

• Now we will create 2 programs of Autowiring using XML Based Configuration
  1. Using <constructor-arg> tag.
  2. Using <property> tag.
  
  

• Program 1

  First we will create program demonstrating autowiring mode as no using <constructor-arg> tag.

  Engine.java

  package in.sp.beans;
  
  public class Engine
  {
      public void start()
      {
          System.out.println("Engine started...");
      }
  }

  Car.java

  package in.sp.beans;
  
  public class Car
  {
      private Engine engine;
  
      // Constructor for dependency injection
      public Car(Engine engine)
      {
          this.engine = engine;
      }
  
      public void drive()
      {
          engine.start();
          System.out.println("Car is running...");
      }
  }

  applicationContext.xml

  
  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="
          http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
  
      <!-- Define Engine bean -->
      <bean id="engine" class="in.sp.beans.Engine" />
  
      <!-- Define Car bean with constructor-based dependency injection -->
      <bean id="car" class="in.sp.beans.Car">
          <constructor-arg ref="engine" />
      </bean>
  
  </beans>
  

  MainApp.java

  package in.sp.main;
  
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.support.ClassPathXmlApplicationContext;
  
  import in.sp.beans.Car;
  
  public class MainApp
  {
  	public static void main(String[] args)
  	{
  		// Load Spring context from XML configuration
          ApplicationContext context = new ClassPathXmlApplicationContext("in/sp/resources/applicationContext.xml");
  
          // Retrieve the Car bean
          Car car = context.getBean(Car.class);
  
          // Call the drive method
          car.drive();
  	}
  }

  Below is the output

  Output:

  Engine started...
  Car is running...

  
  
  

• Program 2

  Now we will create second program demonstrating autowiring mode as no using <property> tag.

  Engine.java

  package in.sp.beans;
  
  public class Engine
  {
      public void start()
      {
          System.out.println("Engine started...");
      }
  }

  Car.java

  package in.sp.beans;
  
  public class Car
  {
      private Engine engine;
  
      // Setter method for dependency injection
      public void setEngine(Engine engine)
      {
          this.engine = engine;
      }
  
      public void drive()
      {
          engine.start();
          System.out.println("Car is running...");
      }
  }

  applicationContext.xml

  
  <?xml version="1.0" encoding="UTF-8"?>
  <beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="
          http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
  
      <!-- Define Engine bean -->
      <bean id="engine" class="in.sp.beans.Engine" />
  
      <!-- Define Car bean with explicit dependency injection -->
      <bean id="car" class="in.sp.beans.Car">
          <property name="engine" ref="engine" />
      </bean>
  
  </beans>
  

  MainApp.java

  package in.sp.main;
  
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.support.ClassPathXmlApplicationContext;
  
  import in.sp.beans.Car;
  
  public class MainApp
  {
  	public static void main(String[] args)
  	{
  		// Load Spring context from XML configuration
          ApplicationContext context = new ClassPathXmlApplicationContext("in/sp/resources/applicationContext.xml");
  
          // Retrieve the Car bean
          Car car = context.getBean(Car.class);
  
          // Call the drive method
          car.drive();
  	}
  }

  Below is the output

  Output:

  Engine started...
  Car is running...