Hi, I just prepared a presentation on Java Spring Framework, the topics covered include architecture of Spring framework and it's modules. Spring Core is explained in detail including but not limited to Inversion of Control (IoC), Dependency Injection (DI) etc. Thank you and happy learning. :)
2. Know your trainer
Name: Arjun
Phone : +91 9691053479
Email: thakurarjun247@gmail.com
Freelance corporate trainer.
More than 2 years of strong hands-on experience in top MNCs in Java
and related technologies.
More than 2 years of experience as a Java trainer.
Clients / Previous Employers:
2
3. Agenda
Topics to be covered are:
Introduction to Spring framework
Benefits of Spring framework
Spring framework architecture
Inversion of Control (IoC)
Dependency Injection (DI)
3
4. Spring Framework
Light-weight comprehensive framework for building Java SE and
Java EE applications
Created by Rod Johnson
JavaBeans-based configuration management, applying Inversionof-Control principles, specifically using the Dependency Injection
technique
• Reduce dependencies of components on specific
implmentation of other components.
• A core bean factory, which is usable globally
Generic abstraction layer for database transaction management
4
5. Key Features
Built-in generic strategies for JTA and a single JDBC DataSource
This removes the dependency on a Java EE environment for
transaction support.
Integration with persistence frameworks Hibernate, JDO and
iBATIS.
MVC web application framework, built on core Spring functionality,
supporting many technologies for generating views, including JSP.
Extensive aspect-oriented programming (AOP) framework to
provide
services such as transaction management.
As with the Inversion-of-Control parts of the system, this aims to
improve the modularity of systems created using the framework.
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6. Using Spring
Wiring of components through Dependency Injection
Promotes de-coupling among the parts that make the
application
Test-Driven Development (TDD)
POJO classes can be tested without being tied up with
the framework
Declarative programming through AOP
Easily configured aspects, esp. transaction support
Integration with other technologies
EJB for J2EE
Hibernate, iBatis, JDBC (for data access)
Velocity (for presentation)
Struts and WebWork (For web)
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8. Core Package
The fundamental part which provides the IoC and Dependency
Injection features
BeanFactory, provides a sophisticated implementation of the
factory pattern
Removes the need for programmatic singletons
Decouple the configuration and specification of dependencies in
program logic.
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9. Context Package
Provides a way to access objects in a framework-style
Inherits its features from the beans package and adds support for
• internationalization (I18N)
• event-propagation
• resource-loading
• transparent creation of contexts by
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10. DAO Package
Provides a JDBC-abstraction layer that removes the need to do
tedious
JDBC coding and parsing of database-vendor specific error codes
Programmatic as well as declarative transaction management for
• classes implementing special interfaces
• POJOs
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11. ORM Package
The ORM package provides integration layers for popular objectrelational mapping APIs, including JPA, JDO, Hibernate, and iBatis.
Using the ORM package you can use all those O/R-mappers in
combination with all the other features Spring offers, such as the
simple declarative transaction management feature mentioned
previously
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12. AOP Package
Spring's AOP package provides an AOP Alliance-compliant aspectoriented programming implementation
• method-interceptors and pointcuts to cleanly decouple code
implementing functionality that should logically speaking be
separated
Using source-level metadata functionality you can also incorporate all
kinds of behavioral information into your code
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13. MVC Package
Web package provides features, such as
• multipart file-upload functionality,
• the initialization of the IoC container using servlet listeners
• A web-oriented application context.
• Can be used together with WebWork or Struts,
Spring's MVC package provides a Model-View-Controller (MVC)
implementation for web applications
Provides a clean separation between domain model code and web
forms, and allows all the other features of the Spring Framework.
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15. Inversion of Control
The Spring IoC container makes use of Java POJO classes and
configuration metadata.
It produces a fully configured and executable system or application.
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16. Introduction to IoC
Traditional software is developed with the application code “in
control”
• The application defines the “main”function/method/entry point
• Calls the application’s components to perform processing
Frameworks invert this relationship and call the application code
• “Don’t call us we’ll call you”
• Framework provides the “main”function/method/entry point
• Application code fits into the framework and is called when the
framework decides.
A particular variant of IoC is “dependency injection”
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17. Dependency Injection
Most frameworks use the “Service Lookup” approach to allow
application code to find its dependencies.
• e.g. J2EE code looks up resources via JNDI
• CORBA applications find services via a Naming Service
• The lookup mechanism is hard coded into the application code
Dependency Injection frameworks supply the resources that a
component needs when initialising it
• Component declares resources required (usually as interface
types)
• Framework configuration defines concrete instances to use
• Framework passes component the concrete resources at load
time
“IoC containers” are “Dependency Injection” containers
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19. IoC Container
The org.springframework.beans and org.springframework.context
packages provide the basis for the Spring Framework's IoC container.
BeanFactory interface
provides an advanced configuration mechanism capable of managing
objects of any nature.
ApplicationContext interface , a sub interface of BeanFactory is used
for
• Easier integration with Spring's AOP features,
• Message resource handling (in internationalization),
• Event propagation
• Specific contexts such as the WebApplicationContext
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20. Container and Beans
A bean is simply an object that is instantiated, assembled and
otherwise managed by a Spring IoC container
The beans, and the dependencies between them, are reflected in
the configuration metadata used by a container.
org.springframework.beans.factory.BeanFactory is the representation
of the Spring IoC container, it’s responsible for:
• containing and managing beans,
• instantiating or sourcing application objects
• configuring such objects
• assembling the dependencies between objects.
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21. The Container
There are a number of implementations of the BeanFactory interface
The most commonly used BeanFactory implementation is the
XmlBeanFactory class.
The XmlBeanFactory takes the XML configuration metadata and uses
it to create a fully configured system or application.
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22. Configuration Meta Data
The meta-data informs the Spring container as to how to “instantiate,
configure, and assemble *the objects in your application+”.
XML-based metadata is the most commonly used form of
configuration metadata.
Configuration consists of at least one bean definition that the
container must manage, but could be more than one bean definition.
When using XML-based configuration metadata, these beans are
configured as <bean/> elements inside a top-level <beans/> element.
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23. Simple XML Configuration
<?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-beans2.5.xsd">
<bean id="..." class="...">
<!--collaborators and configuration for this bean go here -->
</bean>
<bean id="..." class="...">
<!--collaborators and configuration for this bean go here -->
</bean>
<!--more bean definitions go here -->
</beans>
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24. Instantiating a Container
ApplicationContext context = new ClassPathXmlApplicationContext(
new String[] {"services.xml", "daos.xml"});
// an ApplicationContext is also a BeanFactory (via inheritance)
BeanFactory factory = context;
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25. The Bean
The container manages the beans , and they are are created using
the configuration metadata.
Bean definitions are represented as BeanDefinition objects, which
contain the following metadata:
package-qualified class name: typically this is the actual
implementation class of the bean being defined.
bean behavioral configuration elements,
• which state how the bean should behave in the container (scope,
lifecycle callbacks etc.,).
references to other beans
• which are needed for the bean to do its work; these references
are also called collaborators or dependencies.
other configuration settings
• An example would be the number of connections to use in a
bean that manages a connection pool, or the size limit of the
pool.
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26. Benefits of Dependency Injection
Flexible
• Avoid adding lookup code in business logic
Testable
• No need to depend on external resources or containers for
testing
Maintainable
• Promotes a consistent approach across all applications and
teams
• Allows reuse in different application environments by changing
configuration files instead of code
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27. Dependency Injection
BeanFactory interface
XmlBeanFactory implementation
Bean configuration file
Constructor dependency Injection
• Dependencies are provided through the constructors of the
component
Setter dependency injection
• Dependencies are provided through the JavaBeanstyle setter
methods of the component
• More popular than Constructor dependency injection
Beans
Injection Parameters
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28. BeanFactory Class
BeanFactory object is responsible for managing beans and their
dependencies
Your application interacts with Spring's DI container through
BeanFactory interface
• BeanFactory object has to be created by the application typically
XmlBeanFactory
• BeanFactory object, when it gets created, read bean
configuration file and performs the wiring
• Once created, the application can access the beans via
BeanFactory interface
XmlBeanFactory
• Convenience extension of DefaultListableBeanFactory that reads
bean definitions from an XML document
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29. Beans
The term “bean” is used to refer any component managed by the
BeanFactory
The “beans” are in the form of JavaBeans (in most cases)
• no arg constructor
• getter and setter methods for the properties
Beans are singletons by default
Properties
• the beans may be simple values or references to other beans
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30. The Bean – A Java Class
public class Example {
private int empid;
private String empname;
public int getEmpid() {
return empid;
}
public void setEmpid(int empid) {
this.empid = empid;
}
public String getEmpname() {
return empname;
}
public void setEmpname(String empname) {
this.empname = empname;
}
public Example() {super();}} // no arg constructor
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31. Injecting Simple Values–XML File
Each bean is defined using <bean> tag under the root of the <beans>
tag
The id attribute is used to give the bean its default name
The class attribute specifies the type of the bean
<bean id="firstBean" class="com.training.Example">
<property name="empname">
<value>ramesh</value>
</property>
<property name="empid"><value>100</value></property>
</bean>
</beans>
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32. Injecting Simple Values–XML File
Each bean is defined using <bean> tag under the root of the <beans>
tag
The id attribute is used to give the bean its default name
The class attribute specifies the type of the bean
<bean id="firstBean" class="com.training.Example">
<property name="empname">
<value>ramesh</value>
</property>
<property name="empid"><value>100</value></property>
</bean>
</beans>
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33. Spring Application
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
public class TestExample {
public static void main(String[] args) {
BeanFactory bfact = new XmlBeanFactory(new
FileSystemResource("mybean.xml"));
Example exObj = (Example)bfact.getBean("firstBean");
System.out.println(exObj.getEmpid());
System.out.println(exObj.getEmpname());
}
}
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34. Injection Parameter Types
Spring supports various kinds of injection parameters
• Simple values
• Beans in the same factory
• Beans in another factory
• Collections
• Externally defined properties
You can use these types for both setter or constructor injections
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35. Injecting Bean into the same Factory
Used when you need to inject one bean into another (target bean)
Configure both beans first
Configure an injection using <ref> tag in the target bean's <property>
or <constructor-arg>
The type being injected does not have to be the exact type defined
on the target
if the type defined on the target is an interface, the type being
injected must be an implementation of it
if the type defined on the target is a class, the type being injected can
be the same type or sub-type
35
36. Constructor Injection
All dependencies injected via constructor arguments
– Requires potentially complex constructor argument lists
Avoids reliance on get/set naming conventions
– e.g. addStateObserver()
Less flexible initialisation
– Need a constructor per configuration option
Can be difficult to understand
– Rely on ordering of parameters
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37. Constructor Dependency Injection
(code snippet)
public class Invoice {
private Items item;
private String customer;
private double amount;
public Invoice(Items item)
{
this.item = item;
}
public Invoice()
{
super();
}
// Set/Get Methods
}
public class Items {
private int itemno;
private String itemname;
public Items() {
super();
}
// Set/Get Methods
}
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38. Constructor Dependency Injection
(code snippet)
public class TestConstDepend {
public static void main(String[] args) {
BeanFactory bf = new XmlBeanFactory(new
FileSystemResource("mybeandef.xml"));
Invoice inv = (Invoice)bf.getBean("Invoice");
System.out.println(inv.getItem());
System.out.println(inv.getCustomer());
System.out.println(inv.getAmount());
}
}
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39. Setter Injection
All dependencies injected via setter methods
– No need for constructors
Allows flexible initialisation
– Any set of properties can be initialised
Named properties allow for readable configuration data
– Clear what is being injected
Requires JavaBean conventions to be followed
– Non standard method names are problematic
Can result in invalid object configurations
– Need post initialisation checking methods
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40. Setter Injection (code snippet)
public class Policy {
private int policyCode;
private String policyName;
public Policy(int policyCode,
String policyName) {
this.policyCode =
policyCode;
this.policyName =
policyName;
}
public Policy() {
super();
}
//SET-GET Methods
}
public class Insurance {
private int policynumber;
private Policy policyData;
public Policy getPolicyData() {
return policyData;
}
public void
setPolicyData(Policy
policyData) {
this.policyData =
policyData;
}
//SET-GET Methods
}
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41. Setter Injection (code snippet)
public class TestSetterDependcy {
public static void main(String[] args) {
BeanFactory beanFact = new XmlBeanFactory
(new FileSystemResource("myBean.xml"));
Insurance ins =(Insurance)beanFact.getBean("Insurance");
System.out.println("Policy Number"+ins.getPolicynumber());
System.out.println("Policy Code“ +
ins.getPolicyData().getPolicyCode());
System.out.println("Policy Holder Name"+
ins.getPolicyData().getPolicyName());
}
}
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