This spring tutorial provides in-depth concepts of Spring Framework with simplified examples. It was developed by Rod Johnson in 2003. Spring framework makes the easy development of JavaEE application.

It is helpful for beginners and experienced persons.

Spring is a lightweight framework. It can be thought of as a framework of frameworks because it provides support to various frameworks such as Struts, Hibernate, Tapestry, EJB, JSF, etc. The framework, in broader sense, can be defined as a structure where we find solution of the various technical problems.

The Spring framework comprises several modules such as IOC, AOP, DAO, Context, ORM, WEB MVC etc. We will learn these modules in next page. Let's understand the IOC and Dependency Injection first.

These are the design patterns that are used to remove dependency from the programming code. They make the code easier to test and maintain. Let's understand this with the following code:

1. class Employee{  
2. Address address;  
3. Employee(){  
4. address=new Address();  
5. }  
6. }  

In such case, there is dependency between the Employee and Address (tight coupling). In the Inversion of Control scenario, we do this something like this:

1. class Employee{  
2. Address address;  
3. Employee(Address address){  
4. this.address=address;  
5. }  
6. }  

Thus, IOC makes the code loosely coupled. In such case, there is no need to modify the code if our logic is moved to new environment.

In Spring framework, IOC container is responsible to inject the dependency. We provide metadata to the IOC container either by XML file or annotation.

• makes the code loosely coupled so easy to maintain
• makes the code easy to test

There are many advantages of Spring Framework. They are as follows:

Spring framework provides templates for JDBC, Hibernate, JPA etc. technologies. So there is no need to write too much code. It hides the basic steps of these technologies.

Let's take the example of JdbcTemplate, you don't need to write the code for exception handling, creating connection, creating statement, committing transaction, closing connection etc. You need to write the code of executing query only. Thus, it save a lot of JDBC code.

The Spring applications are loosely coupled because of dependency injection.

The Dependency Injection makes easier to test the application. The EJB or Struts application require server to run the application but Spring framework doesn't require server.

Spring framework is lightweight because of its POJO implementation. The Spring Framework doesn't force the programmer to inherit any class or implement any interface. That is why it is said non-invasive.

The Dependency Injection feature of Spring Framework and it support to various frameworks makes the easy development of JavaEE application.

It provides powerful abstraction to JavaEE specifications such as JMS, JDBC, JPA and JTA.

It provides declarative support for caching, validation, transactions and formatting.

 =============================================================================

1. Spring Modules
2. Test
3. Spring Core Container
4. AOP, Aspects and Instrumentation
5. Data Access / Integration
6. Web

The Spring framework comprises of many modules such as core, beans, context, expression language, AOP, Aspects, Instrumentation, JDBC, ORM, OXM, JMS, Transaction, Web, Servlet, Struts etc. These modules are grouped into Test, Core Container, AOP, Aspects, Instrumentation, Data Access / Integration, Web (MVC / Remoting) as displayed in the following diagram.

This layer provides support of testing with JUnit and TestNG.

The Spring Core container contains core, beans, context and expression language (EL) modules.

These modules provide IOC and Dependency Injection features.

This module supports internationalization (I18N), EJB, JMS, Basic Remoting.

It is an extension to the EL defined in JSP. It provides support to setting and getting property values, method invocation, accessing collections and indexers, named variables, logical and arithmetic operators, retrieval of objects by name etc.

These modules support aspect oriented programming implementation where you can use Advices, Pointcuts etc. to decouple the code.

The aspects module provides support to integration with AspectJ.

The instrumentation module provides support to class instrumentation and classloader implementations.

This group comprises of JDBC, ORM, OXM, JMS and Transaction modules. These modules basically provide support to interact with the database.

This group comprises of Web, Web-Servlet, Web-Struts and Web-Portlet. These modules provide support to create web application. 

==============================================================================

1. Steps to create spring application

Here, we are going to learn the simple steps to create the first spring application. To run this application, we are not using any IDE. We are simply using the command prompt. Let's see the simple steps to create the spring application

• create the class
• create the xml file to provide the values
• create the test class
• Load the spring jar files
• Run the test class

Let's see the 5 steps to create the first spring application.

This is the simple java bean class containing the name property only.

1. package com.javatpoint;  
2. public class Student {  
3. private String name;  
4. public String getName() {  
5. return name;  
6. }  
7. public void setName(String name) {  
8. this.name = name;  
9. }  
10. public void displayInfo(){  
11.     System.out.println("Hello: "+name);  
12. }  
13. }  

This is simple bean class, containing only one property name with its getters and setters method. This class contains one extra method named displayInfo() that prints the student name by the hello message.

In case of myeclipse IDE, you don't need to create the xml file as myeclipse does this for yourselves. Open the applicationContext.xml file, and write the following code:

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans  
3.     xmlns="http://www.springframework.org/schema/beans" 
4.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
5.     xmlns:p="http://www.springframework.org/schema/p" 
6.     xsi:schemaLocation="http://www.springframework.org/schema/beans 
7.                http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> 
8. <bean id="studentbean" class="com.javatpoint.Student">  
9. <property name="name" value="Vimal Jaiswal"></property>  
10. </bean>  
11. </beans>  

The bean element is used to define the bean for the given class. The property subelement of bean specifies the property of the Student class named name. The value specified in the property element will be set in the Student class object by the IOC container.

Create the java class e.g. Test. Here we are getting the object of Student class from the IOC container using the getBean() method of BeanFactory. Let's see the code of test class.

1. package com.javatpoint;  
2. import org.springframework.beans.factory.BeanFactory;  
3. import org.springframework.beans.factory.xml.XmlBeanFactory;  
4. import org.springframework.core.io.ClassPathResource;  
5. import org.springframework.core.io.Resource;  
6. public class Test {  
7. public static void main(String[] args) {  
8.     Resource resource=new ClassPathResource("applicationContext.xml");  
9.     BeanFactory factory=new XmlBeanFactory(resource);  
10.     Student student=(Student)factory.getBean("studentbean");  
11.     student.displayInfo();  
12. }  
13. }  

The Resource object represents the information of applicationContext.xml file. The Resource is the interface and the ClassPathResource is the implementation class of the Reource interface. The BeanFactory is responsible to return the bean. The XmlBeanFactory is the implementation class of the BeanFactory. There are many methods in the BeanFactory interface. One method is getBean(), which returns the object of the associated class.

There are mainly three jar files required to run this application.

• org.springframework.core-3.0.1.RELEASE-A
• com.springsource.org.apache.commons.logging-1.1.1
• org.springframework.beans-3.0.1.RELEASE-A

ADAD

For the future use, You can download the required jar files for spring core application.

download the core jar files for spring

download the all jar files for spring including core, web, aop, mvc, j2ee, remoting, oxm, jdbc, orm etc.

To run this example, you need to load only spring core jar files.

Now run the Test class. You will get the output Hello: Vimal Jaiswal.