Spring Containers

• Spring Containers are Provided to take care of Spring Beans Life Cycle.
• Spring containers are also perform Dependency Injection on Spring beans in 2 ways, in configuration file every bean/resource configured with '<bean>' tag.
• If we use '<property>' tag to perform dependency injection then container performs 'setter-injection' ,if we use '<constructor-arg>'    tag to perform dependency injection  then container performs 'Constructor-Injection' mode dependency injection.
• The Java classes that we are using as resources of spring application are called as Spring Resources.
• To configure these Spring Beans we need Spring configuration file. 'anyname'.xml can be taken as spring configuration file.
• Underlying container will use this configuration file to recognize resources.

Spring Provides 2 containers,They are

1. BeanFactory                                                          
2. ApplicationContext

BeanFactory:

• To Activate 'BeanFactory'  we need an Object of class which implements "org.springframework.beans.factory.BeanFactory"  interface.
• "org.springframework.beans.factory.xml.XmlBeanFactory" is most commonly used implementation class of 'BeanFactory' interface.
• To create Object of 'XmlBeanFactory' we need 'FileSystemResource' Object

Activating 'BeanFactory' Container.....

//Creating a resource
FileSystemRecource res=new FileSystemResource("springcfgfile.xml");
                                   or
ClassPathResource res=new ClassPathReosurce("springcfgfile.xml");

//Activate 'BeanFactory' container.
XmlBeanFactory factory=new XmlBeanFactory(res);

FileSystemResource: locates the given spring configuration file from the specified path of File System.

ClassPathResource: locates the given spring configuration file from the directories & jars that are added in class-path.

ApplicationContext:

• ApplicationContext container is Enhancement of BeanFactory Container. 
• To Activate 'ApplicationContext'  we need an Object of class which implements "org.springframework.context.ApplicationContext"  interface.
• There are 3 popular classes implementing the this Interface

• FileSystemAmlApplicationContext: Activates Spring Container by reading the spring configuration file from the specified path of 'File System'.

FileSystemXmlApplicationContext context=new FileSystemXmlApplicationContext("springconfigurationfile.xml");
                                                   or
ApplicationContext context=new FileSystemXmlApplicationContext("springconfigurationfile.xml");

• ClassPathXmlApplicationContext: Activates Spring Container by reading the spring configuration file from the class path folders & jars.

ClassPathXmlApplicationContext context=new ClassPathXmlApplicationContext("springconfigurationfile.xml");
                                                 or
ApplicationContext context=new ClassPathXmlApplicationContext("springconfigurationfile.xml");

• WebXmlApplicationContext: Activates Spring Container by reading the spring configuration file from web application resources(in web environment).

Activating ApplicationContext in web environment.