Spring Tutorials

The core of spring framework is it’s bean factory and mechanisms to create and manage such beans inside Spring container. The beans in spring container can be created in five scopes.That are as follows:

1. singleton: scopes to a single object instance per Spring IOC Container.
2. prototype: scopes to any number of object instances.
3. request: scopes to the lifecycle of a single HTTP request, available only when using a web aware ApplicationContext.
4. session: scopes to the lifecycle of an HTTP session, also available only when using a web aware ApplicationContext.
5. global session: scopes to the lifecycle of a global HTTP session, also available only when using a web aware ApplicationContext.

If scope is set to singleton, the Spring IoC container creates exactly one instance of the object defined by that bean definition. This single instance is stored in a cache of such singleton beans, and all subsequent requests and references for that named bean return the cached object.

The default scope is always singleton however, when you need one and only one instance of a bean, you can set the scope property to singleton in the bean configuration file, as shown below:

<bean id=".." class=".." scope="singleton"></bean>

Example

Let us have working Eclipse IDE in place and follow the following steps to create a Spring application:

Step1. Now you create a simple Java Project using Eclipse IDE. Follow the option File -> New -> Project and finally select Java Project wizard from the wizard list. Now name your project asSpringScope using the wizard window.

Step2. Now add spring jar in your project, To do this, right click on your project name SpringScope and then follow the following option available in context menu: Build Path -> Configure Build Path to display the Java Build Path window as given below. There are mainly three jar files required to run this application, To load the jar files in eclipse IDE, Right click on your project - Build Path - Add external archives - select all the required jar files - finish.

1. antlr-runtime-3.0.1
2. org.springframework.aop-3.1.0
3. org.springframework.asm-3.1.0.
4. org.springframework.aspects-3.1.0.
5. org.springframework.beans-3.1.0.
6. org.springframework.context.support-3.1.0.
7. org.springframework.context-3.1.0.
8. org.springframework.core-3.1.0.
9. org.springframework.expression-3.1.0.
10. commons-logging-1.1.1

Step3. Now you create simply java file with any name. First we need to create a package with any name like com.r4r. To do this, Right click on src in package explorer section and follow the option : New -> Package. and then Right click on package(com.r4r) - New - class - Write the class name e.g. Demo - finish. Write the following code:

package com.r4r;
public class Demo {
private String message;
public void setMessage(String message){
this.message = message;
}
public void getMessage(){
System.out.println("Your Message: " + message);
}}

Step4. Now create the xml file click on src- new -file -give the file name like Beans.xml then finish.

<?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-3.0.xsd">
<bean id="demo" class="com.r4r.Demo" scope="singleton">
</bean>
</beans>

Step5.Now Create the java Main class(MainApp.java), Here we are getting the object of Demo class from the IOC container using the getBean() method of BeanFactory.

package com.r4r;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = 
	new ClassPathXmlApplicationContext("Beans.xml");
Demo d1 = (Demo) context.getBean("demo");
d1.setMessage("Spring is very Easy Framework.");
d1.getMessage();
Demo d2 = (Demo) context.getBean("demo");
d2.getMessage();
}}

Now run the Application you see the following output