Spring Hello World

Spring Hello World

Hello Friends,

Nice to see you again.

In Previous Session  we have seen What is Spring.?.  And learn theory aspect.

Today, we will see the example of  Hello World with Spring  Framework of Java.

So be ready to learn this simple example of Spring Framework Tutorail in JAVA Application..

After apply this code in action, you will be capable of using Spring in your Java Applications.

First Download the required JAR to run Spring Framework in Eclipse as shown Below.

To use Spring in your project follow below steps.

1) First create HelloWorld.java class file  As shown below.

        The HelloWorld class has a message property and its value is set using the

        setMessage()   method.  This is called setter injection. Instead of directly hard 

        coding the message, we inject it through an external configuration file. 

        The design pattern used here is called Dependency Injection design pattern

The HelloWorld class also has a display() method to display the message.

--------------------------------------------------------------------------------------------------------------------

package com.test;
/**
 *
 * @author Nirav Raval
 * this class is used to set Property Values.
 * and will display it to user.
 *
 */
public class HelloWorld {

 private String message;
 private String name;
 
 public void setMessage(String message) {

  this.message = message;
 }

 public void display()
 {
  System.out.println(message);
  System.out.println(name);
 } 
    public void setName(String name) {
  this.name = name;
 }
}

       -------------------------------------------------------------------------------------------------------------


2)      The next step is to add an entry for this in the bean configuration file.
       The bean configuration file is used to configure the beans in the
        Spring IoC  container.

       To create a new bean configuration file right click the src folder and select
       New -> Spring Bean Configuration File.. Save as beans.xml file.

        And write below lines in it.


           -----------------------------------------------------------------------------------------------------------

<?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">

<bean id="helloWorld" class="com.test.HelloWorld">

<property name="message" value="Hello World.!">
                              </property>

<property name="name" value="Nirav Raval!">
                             </property>

</bean>

</beans>

Here, If you want to display a differnt message, the only change you need
to is to change the value of the message in the bean configuration
file. This is one of the main benefits of using the Dependency Injection
design pattern, this makes the code loosely coupled.

       -------------------------------------------------------------------------------------------------------------

3)     Now Finally, To dispaly the message, create the following
       HelloWorldApplication.java  class.


       -------------------------------------------------------------------------------------------------------------

package com.test;

/**
 * 
 * @author Nirav Raval
 * 
 */
import org.springframework.context.
      ApplicationContext;
import org.springframework.context.
       support.ClassPathXmlApplicationContext;

public class HelloWorldApplication {

 public static void main(String[] args) {
  
  ApplicationContext context = 
   new ClassPathXmlApplicationContext("beans.xml");
  
  HelloWorld helloWorld = 
   (HelloWorld) context.getBean("helloWorld");
  
  helloWorld.display();
   
  }
}

After done above steps our directory structure of project in Eclipse PAckage Explorer is as below.

Ok this is done.  Now run HelloWorldApplication.java  to see output in console.


The output will be like as shown below.

What we are doing here is,
First we instantiate the Spring IoC container with the bean configuration file beans.xml.
We use the getBean() method to retrive the helloWorld bean from the application context
and call the display() method to display the message in the console.
---------------------------------------------------------------------------------------------------------------


So I hope this code is helpful in understanding the working of Spring 
Framework in JAVA.


Feel free to ask me if you have any dought regarding this.
You can also give me suggessions to improve this tutorial.


Leave comments if you like this post...!


Thank you.
Nirav Raval