Spring tutorial - Hello World Sample Example

In the previous tutorials, we have already discussed the Spring Introduction, Spring Architecture and Spring Environmental Setup. Now that we are clear on those topics we can move forward. Keeping in mind the basic programming practices, today in this tutorial we are going to create a sample spring based Hello world application.

Follow the steps to create the application:

Step1 – Create a java project

Using Eclipse create a new java project. Java project can be created by File à New à Project à Java Project. A wizard window will open where we have to give the name to the project. Enter the name as HelloWorld.

Below is the screenshot

After the project is created you will see below entries

Step2 – Add required Libraries

Now that the sample java application is created, we must add the Spring framework and common logging jars into the project. To do that Right-click on HelloWorld à Build Path à Configure Build Path à Libraries tab.

On the left side, click on Add External Jars and add the below jars by downloading them manually.

        1.     Commons-loggin-1.1.1

        2.     Spring-aop-4.1.6.RELEASE

        3.     Spring-aspects-4.1.6.RELEASE

        4.     Spring-beans-4.1.6.RELEASE

        5.     Spring-context-4.1.6.RELEASE

        6.     Spring-context-support-4.1.6.RELEASE

        7.     Spring-core-4.1.6.RELEASE

        8.     Spring-expression-4.1.6.RELEASE

        9.     Spring-instrument-4.1.6.RELEASE

        10.  Spring-instrument-tomcat-4.1.6.RELEASE

        11.  Spring-jdbc-4.1.6.RELEASE

        12.  Spring-jms-4.1.6.RELEASE

        13.  Spring-messaging-4.1.6.RELEASE

        14.  Spring-orm-4.1.6.RELEASE

        15.  Spring-oxm-4.1.6.RELEASE

        16.  Spring-test-4.1.6.RELEASE

        17.  Spring-tx-4.1.6.RELEASE

        18.  Spring-web-4.1.6.RELEASE

        19.  Spring-webmvc-4.1.6.RELEASE

        20.  Spring-webmvc-portlet-4.1.6.RELEASE

        21.  Spring-websocket-4.1.6.RELEASE

Step 3 – Source file creation

Now the application configurations are ready. We can jump into coding. First, create the desired package ( for example com.java8bysourabhrai ), right-click on the src à  New à package.

Create HelloWorld.java and MainApp.java under com.java8bysourabhrai.

Write the following code into these files:

HelloWorld.java

MainApp.java

There are two main class that we have seen in the above code, these class are:

        1.     ApplicationContext – Using ApplicationContext we can implement IoC in spring. This we will see in further chapters. ClassPathXmlApplicationContext() is the implementation of ApplicationContext. This takes the bean name and load the bean from the configuration file and takes care of the object creation of the class.

        2.     getBean() – this method uses the bean id to get the bean reference. The return type of the method is the object so, we need to typecast the object into the required bean object. This object can then be used to call the class methods.

Step 4 – Creating the bean configuration file

This file is an XML file which will act as the configuration file. This configuration file will contain parent tag <beans> and its child tags <bean>. This config file will contain the entries of all the beans that we will use into the project.

We need to write the following code into the config file:

Check the availability of this file in classpath. The <bean> tag will reflect the concern bean by property class. The property id will act as an object to the class. Using the id attribute we can call any method of the class. <property> tag will represent the data member of the class with a name attribute and its value by value attribute.

Step 5 – Running the application

Everything is set. Now the remaining work is to run the application. Compiling and running the application is the last step to follow creating the source and configuration files. To the run, the application using eclipse open SpringMainApp.java, use the Run option available in the eclipse or press Ctrl+F11. If there is no error then the following output will be printed.

Spring Hello World: welcome

With the end of this tutorial, our first spring application is created. To print another message change the message property in the configuration file.

This was all about how to create the “Hello World” example of spring application. In the further chapter, we will discuss “IoC Container”