Spring Framework Java

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Spring Framework Tutorials
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Using MessageSourceto get text from properties
file
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Introduction to Spring
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Spring is a light weight and open source
framework created by Rod Johnson in 2003. 
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Spring framework makes the development of
Java/JavaEE application easy.
AOP
Dependency Injection
Dtababase Connectivity
Transaction Management
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Spring can be thought of as a framework of
frameworks because it provides support to various
frameworks such as Struts, Hibernate, EJB, JSF
etc.
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Spring enables you to build applications from
plain old Java objects (POJOs).
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Spring framework is said to be a non-invasive mean
s it doesnt force a programmer to extend or
implement their class from any predefined class
or interface given by Spring API.
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Spring applications are loosely coupled because
of dependency injection and Inversion of
Control(IOC).
Address instance
Third Party
Loose Coupling
Tight Coupling
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Spring Modules
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Core Container

• Core and Beans These modules provide IOC and
  Dependency Injection features.
• Context This module supports internationalization
  (I18N), EJB, JMS, Basic Remoting.
• SpEL It is an extension to the EL defined in
  JSP. It provides support to setting and getting
  property values, method invocation, accessing
  collections, named variables, logical and
  arithmetic operators, retrieval of objects by
  name etc.

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Data Access / Integration-

• These modules basically provide support to
  interact with the database.
• The JDBC module removes the need to do tedious
  JDBC coding.
• ORM module is used to tie up with ORM tools such
  as hibernate.

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Web

• These modules provide support to create web
  application.

Test

• This module supports the testing of Spring
  components with JUnit or TestNG.

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Dependency Injection IOC
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Dependency Injection

• Dependency Injection (DI) is a software design
  pattern that deals with how components get hold
  of their dependencies.
• A class X has a dependency to class Y, if class X
  uses class Y as a variable.
• Java components / classes should be as
  independent as possible of other Java classes.
• This increases the possibility to reuse these
  classes and to test them independently of other
  classes(Unit Testing).
• Dependency injection is a style of object
  configuration in which an objects fields are set
  by an external entity, in other words objects are
  configured by an external entity.
• Dependency injection is an alternative to having
  the object configure itself. 

class X Y y
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Dependency Injection and Inversion of Control
Dependency
Injection
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Dependency Injection and Inversion of Control

• Inversion of Control is a principle by which the
  control of objects is transferred to a container
  or framework.
• Dependency injection is a pattern through which
  IoC is implemented, where the control being
  inverted is the setting of objects dependencies.
• The act of connecting objects with other objects,
  or injecting objects into other objects, is
  done by container rather than by the objects
  themselves.
• A class should not configure itself but should be
  configured from outside.

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Dependency Injection and Inversion of Control

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

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Dependency Injection

• Spring framework provides two ways to inject
  dependency
• By Constructor (Constructor Injection)-In the
  case of constructor-based dependency injection,
  the container will invoke a constructor with
  arguments each representing a dependency we want
  to set.
• By Setter method (Setter Injection)-For
  setter-based DI, the container will call setter
  methods of our class.

With IOC (setter Injection)
Without IOC
With IOC (constructor Injection)
class Employee Address address Employee()
addressnew Address(XYZ Street, Pune,
MH) ..
class Employee   Address address      public voi
d setAddress(Address address)   this.addressaddr
ess       
class Employee   Address address      Employee(A
ddress address)   this.addressaddress      
  
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BeanFactory AplicationContext
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IOC

• In Spring framework, IOC container is responsible
  to inject the dependencies. We provide metadata
  to the IOC container either by XML file or
  annotation.
• The IoC container is responsible to instantiate,
  configure and assemble the objects.

BeanFactory
IOC containers
ApplicationContext
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BeanFactory

• Spring BeanFactory Container is the simplest
  container which provides basic support for DI.
• It is defined by org.springframework.beans.factory
  .BeanFactory interface.
• There are many implementations of BeanFactory
  interface . The most commonly used BeanFactory
  implementation is
• org.springframework.beans.factory.xml.XmlBeanFacto
  ry
• Example-
• Resource resourcenew ClassPathResource(Beans.xml
  ")  
• BeanFactory factorynew XmlBeanFactory(resource)
• The Resource interface has many implementaions.
  Two mainly used are1)org.springframework.core.i
  o.FileSystemResource Loads the resource from
  underlying file system.
• Example-
• BeanFactory bfObj new XmlBeanFactory(new
  FileSystemResource ("c/beansconfig.xml"))
• 2)org.springframework.core.io.ClassPathResourc
  eLoads the resource from classpath. 

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ApplicationContext

• The ApplicationContext container is Springs
  advanced container.
• It is defined by org.springframework.context.Appli
  cationContext interface. 
• The ApplicationContext interface is built on top
  of the BeanFactory interface.
• It adds some extra functionality than
  BeanFactory such as simple integration with
  Spring's AOP, message resource handling (for
  I18N), event propagation etc.
• There are many implementations of
  ApplicationContext interface . The most commonly
  used ApplicationContext implementation is
• org.springframework.context.support.ClassPathXmlAp
  plicationContext
• Example-
• ApplicationContext contextnew
  ClassPathXmlApplicationContext("Beans.xml")

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Spring Autowiring
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Autowiring in Spring

• Autowiring means injecting the object dependency
  implicitly.
• It internally uses setter or constructor
  injection.
• It works with reference only.
• Autowiring can't be used to inject primitive and
  string values.
• By default autowiring is disabled in spring
  framework. 
• Autowiring can be performed by either using
  autowire attribute in ltbeangt or by using
  _at_Autowired annotation.

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Without Autowiring
. ltbean id"address" class"com.tutorials.demo.
Address"gt ltproperty name"street" value"Park
Street"gtlt/propertygt ltproperty name"city"
value"Pune"gtlt/propertygt ltproperty name"state"
value"Maharashtra"gtlt/propertygt lt/beangt ltbean
id"emp" class"com.tutorials.demo.Employee"gt ltp
roperty name"id" value"111"gtlt/propertygt ltproper
ty name"name" value"Ram"gtlt/propertygt ltproperty
name"address" ref"address"gtlt/propertygt lt/beangt
.
public class Employee private int id
private String name private Address
address .
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With Autowiring
. ltbean id"address" class"com.tutorials.demo.
Address"gt ltproperty name"street" value"Park
Street"gtlt/propertygt ltproperty name"city"
value"Pune"gtlt/propertygt ltproperty name"state"
value"Maharashtra"gtlt/propertygt lt/beangt ltbean
id"emp" class"com.tutorials.demo.Employee
autowirebyName"gt ltproperty name"id"
value"111"gtlt/propertygt ltproperty name"name"
value"Ram"gtlt/propertygt lt/beangt .
public class Employee private int id
private String name private Address
address .
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Autowiring modes
No. Mode Description
1) no It is the default autowiring mode. It means no autowiring bydefault.
2) byName The byName mode injects the object dependency according to name of the bean. In such case, property name and bean name must be same. It internally calls setter method.
3) byType The byType mode injects the object dependency according to type. So property name and bean name can be different. It internally calls setter method.
4) constructor The constructor mode injects the dependency by calling the constructor of the class. It calls the constructor having large number of parameters.
5) autodetect It is deprecated since Spring 3.
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Bean Scopes
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Autowiring in Spring

• Autowiring means injecting the object dependency
  implicitly.
• It internally uses setter or constructor
  injection.
• It works with reference only.
• Autowiring can't be used to inject primitive and
  string values.
• By default autowiring is disabled in spring
  framework. 
• Autowiring can be performed by either using
  autowire attribute in ltbeangt or by using
  _at_Autowired annotation.

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