SPRING FRAMEWORKBasics of

1July 27, 2008

Spring Framework

BasicsIntroduction to IoC and AOPSpring CoreAOP in DetailBean LifecycleExtensibilitySpring - The Beginning…

ReferencesQuestions/Feedback

Agenda

2July 27, 2008

Spring Framework

01 Basics

3July 27, 2008

Spring Framework

Spring is a Lightweight, Inversion of Control and Aspect-Oriented Container FrameworkLightweightInversion of ControlAspect OrientedContainerFramework

Spring?

4July 27, 2008

Spring Framework

Play role in Enterprise Application ArchitectureCore SupportWeb Application Development SupportEnterprise Application Development Support

Spring Triangle

Spring Goals

55July 27, 2008

Spring Framework

Spring Triangle

6

Depe

nden

cy In

jecti

on

Aspect Oriented Programm

ing

Enterprise Service Abstractions

6July 27, 2008

Spring Framework

To make J2EE easier to use and promote EBPAlways better to program to interfaces than classesJavaBeans are a great way to configure applicationsFramework should not force to catch exceptions if one is unlikely to recover from themTesting is essential and framework should make it easierTo make integration with existing technologies easierTo easily integrate in existing projects

Spring Objectives

7July 27, 2008

Spring Framework

Organizes middle tier objectsEliminates proliferation of singletonsSpring is mostly non-intrusive*Applications built on Spring are easy to Unit TestUse of EJB becomes an implementation choiceConsistent framework for Data Access whether JDBC or O/R mappingAny part of Spring can be used in isolation.Provides for flexible architectureBenefit to all application layers

Spring Advantages

8July 27, 2008

Spring Framework

Spring Layers

9

Core

AOP Web MVC

ORM Web

DAO Context

July 27, 2008

Spring Framework

ServiceInterface to which we program.

ImplementationConcrete class implementing the service.

WiringAct of creating associations between application components.

Collaborators Services used by a service to perform business operations

Inversion of ControlAOP

Lingua-Franca

10July 27, 2008

Spring Framework

02 Introduction to IoC & AOP

11July 27, 2008

Spring Framework

public class ProductServicesImpl implements ProductServices {

public List getAllProducts(String loanTerm) throws Exception {PricingServiceImpl service = new PricingServiceImpl();return service.getAllProducts(loanTerm);

}}

public class ProductServicesTest extends TestCase {public void testGetAllProducts() {

ProductServices service = new ProductServicesImpl();try { List products = service.getAllProducts(“30”); assertNotNull(products);} catch (Exception e) { assertTrue(false);}

}}

IoC Example

12

ProductServiceImpl

PricingServiceImpl

new

Pric

ingS

ervi

ceIm

pl()

JND

I Loo

kup

July 27, 2008

Spring Framework

public class ProductServicesImpl implements ProductServices {

private PricingService service;

public List getAllProducts(String loanTerm, PricingService service) throws Exception {return service.getAllProducts(loanTerm);

}

public List getAllProducts(String loanTerm) throws Exception {return service.getAllProducts(loanTerm);

}

public void setPricingService(PricingService service) {this.service = service;

}}

IoC Example - revisited

13

ProductServiceImpl

PricingServiceImpl

By s

etter

inje

ction

By c

onst

ruct

or in

jecti

on

July 27, 2008

Spring Framework

It is the acquisition of dependent objects that is being inverted.Hence, can be termed as “Dependency Injection”Applying IoC, objects are given their dependent objects at creation time (at runtime) by some external entity that coordinates with each object in the system.

Inversion of Control

14July 27, 2008

Spring Framework

Complements OOPDecomposition of aspects/concernsModularization of concerns that would otherwise cut across multiple objectsReduces duplicate codeUsages

LoggingPersistenceTransaction ManagementDebuggingPerformance Metrics

Aspect Oriented Programming

15July 27, 2008

Spring Framework

Cross Cutting Concerns

16

Auto Rate Update Job

Generate Loan Products

Loan Prequalification

Reporting Tra

nsac

tion

Man

agem

ent

Sec

urit

y

Log

ging

/Exc

epti

on H

andl

ing

Per

form

ance

Met

rics

July 27, 2008

Spring Framework

Non-AOP representation

Cross Cutting Concerns

17

Auto Rate Update Job

Generate Loan Products

Loan Prequalification

Reporting

Transaction Management

Security

Logging

Performance Metrics

July 27, 2008

AOP representation

Logg

ing

Tran

sacti

on M

anag

emen

t

Security

Spring Framework

Cross Cutting Concerns

18

AutoRate Update Job

Generate Loan Products

Loan Prequalification Reporting

July 27, 2008

Spring Framework

Spring @ Work

19

ConfiguredReady-to-use System

SpringContainerConfiguration Metadata

Business Objects / POJOs

produces

July 27, 2008

Spring Framework

Download the JAR files from,http://www.springframework.org/download

Copy them to the dependency folder.If you start afresh, you might need logging

Add a log4j.properties to the ROOT of class folderAdd the following to the file to direct all logging to console

log4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%d %p %c - %m%nlog4j.rootLogger=INFO, stdoutlog4j.logger.org.springframework=DEBUG (or ERROR)

Start codingBuild your own preferred way using Ant, Maven, …

Spring Installation

20July 27, 2008

Spring Framework

HelloWorldService.javapackage spring;

public interface HelloWorldService {public void sayHello();

}

HelloWorldServiceImpl.javapackage spring;

public class HelloWorldImpl implements HelloWorldService {

private String message;private HelloWorldImpl() { }

public HelloWorldImpl(String message) {this.message = message;

}

public void sayHello() {System.out.println(“Hello “ +

message);}

public void setMessage(String message) {this.message = message;

}}

21

Traditional Hello World!

July 27, 2008

Spring Framework

<?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-2.0.xsd">

<bean id=“helloWorldService“ class="spring.HelloWorldImpl"> <property name=“message"> <value>Welcome to Spring!</value> </property> </bean></beans>

* DTD version for the schema is also available and can be declared as under,<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN 2.0//EN“ "http://www.springframework.org/dtd/spring-beans-2.0.dtd">

Configuring (hello.xml)

22July 27, 2008

Spring Framework

package spring;

import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.xml.XmlBeanFactory;import org.springframework.core.io.ClassPathResource;

public class HelloWorld {

public static void main(String[] args) throws Exception {ClassPathResource resource = new ClassPathResource(“hello.xml”);BeanFactory factory = new XmlBeanFactory(resource);HelloWorldService helloWorldService = (HelloWorldService)

factory.getBean("helloWorldService");helloWorldService.sayHello();

}}

The Actual Implementation – HelloWorld.java

23July 27, 2008

Spring Framework

A service bean using the EJB way,

private OrderService orderService;

public void doRequest(HttpServletRequest request) {Order order = createOrder(request);OrderService service = getOrderService();service.createOrder(order);

}

private OrderService getOrderService() throws CreateException {if (orderService == null) {

Context initial = new InitialContext();Context ctx = (Context) initial.lookup(“java:comp/env”);Object ref = ctx.lookup(“ejb/OrderServiceHome”);OrderServiceHome home = (OrderServiceHome) PortableRemoteObject.narrow(ref, OrderService.class);orderService = home.create();

}return orderService;

}

IoC in an Enterprise Application

24July 27, 2008

Spring Framework

Magic the dependency injection way,

private OrderService orderService;

public void doRequest(HttpServletRequest request) {Order order = createOrder(request);orderService.createOrder(order);

}

public void setOrderService(OrderService service) {orderService = service;

}

IoC in an Enterprise Application

25July 27, 2008

Spring Framework

03 The Core

26July 27, 2008

Spring Framework

may be POJO/EJB/WebServiceSpring’s world revolves all around BeansGenerated using two different containers,

Bean FactoryProvides basic support for dependency injection

Application ContextBuilt over BeanFactory to provide support for i18N, events, and file resources.

Wiring done using bean definitionsSpecified as Configuration Metadata

Spring Beans

27July 27, 2008

Spring Framework

Implementation of Factory design pattern.Creates associations between objects, doles out fully configured, ready to use objects.Manages all the beans in the container.

Bean Factory

2828July 27, 2008

Spring Framework

Using Bean FactoriesIn version 2.0

Resource resource = new FileSystemResource(“beans.xml”);BeanFactory factory = new XmlBeanFactory(resource);

In version 1.0FileInputStream stream = new FileInputStream(“beans.xml”);BeanFactory factory = new XmlBeanFactory(stream);

Instantiating Container

2929July 27, 2008

Spring Framework

In-box wrappers available for,UrlResourceClassPathResourceFileSystemResourceServletContextResourceInputStreamResourceByteArrayResource

Also, provides for loading of resources such as images, css, js etc. in a web application.

Resource Interface

3030July 27, 2008

Spring Framework

Resource Interface,public interface Resource extends InputStreamSource

Methods,boolean exists()boolean isOpen()InputStream getInputStream()String getDescription()

often returns fully qualified file name or the actual URL

URL getURL()File getFile()String getFilename()Resource createRelative(String relativePath)

Resource Interface

3131July 27, 2008

Spring Framework

Aggregates information about the application that can be used by all components.

Various implementations are,ClassPathXmlApplicationContextFileSystemXmlApplicationContextXmlWebApplicationContext

Instantiating,ApplicationContext context = new FileSystemXmlApplicationContext(“c:\spring\

beans.xml”);

Application Context

3232July 27, 2008

Spring Framework

Loading multiple contextsString[] ctxs = new String[] { “ctx1.xml”, “ctx2.xml” };

Loading hiererichal contextsApplicationContext parent = new ClassPathXmlApplicationContext (“ctx1.xml”);ApplicationContext child = new FileSystemXmlApplicationContext(“ctx2.xml”, parent);

Application Context – Multiple Context’s

3333July 27, 2008

Spring Framework

Configuration can be done using,XML configuration filesJava property filesProgrammatically using APIAnnotationsSpring JavaConfig*

Configuration Metadata

3434July 27, 2008

Spring Framework

Bean definition contains the following attributes,id/nameclassscope: singleton/prototype/customconstructor argumentspropertiesauto wiring modedependency checking modelazy-initialization modeinitialization methoddestruction methodand much more…

Defining Bean

35July 27, 2008

Spring Framework

A basic bean definition,<beans>

<bean id=“sampleBean" class=“spring.SampleSpringBeanClass“ scope=“singleton” auto-wire=“byName” dependency-check=“simple” lazy-init=“true” init-method=“myInitMethod” destroy-method=“myDestroyMethod” ><constructor-arg value=“Hello World” /><property name=“prop1” value=“value1” /><property name=“prop2” ref=“anotherBean” />

</bean></beans>

Sample Bean Definition

3636July 27, 2008

Spring Framework

The arcane way of XML,<beans>

<bean id=“sampleBean" class=“spring.SampleSpringBeanClass“><property> <name>prop1</name> <value>value1</value></property>

</bean></beans>

Short-hand notation<property name=“…” value=“…” /><constructor-arg value=“…” /><property name=“…” ref=“…” /><entry key=“…” value=“…” /><entry key-ref=“key reference” value=“…” />

Defining Bean – short-circuit

3737July 27, 2008

Spring Framework

Importing other resources inside another resource<beans>

<import resource="services.xml"/><import resource="resources/messageSource.xml"/><import resource="/resources/themeSource.xml"/><bean id="bean1" class="..."/><bean id="bean2" class="..."/>

</beans>

Separating Concerns

38July 27, 2008

Spring Framework

In bean definition itselfUsing one name in the id attributeAll other names using the “name” attribute

separated by comma, semi-colon, white space

Using the <alias> element<alias name="fromName" alias="toName"/>

Bean Aliases

39July 27, 2008

Spring Framework

By default, all Spring beans are singletonsPrototyped beans are useful when properties need to be set using Spring wiring

<bean id=“example” class=“spring.MyExample” scope=“singleton” /><bean id=“example” class =“spring.MyExample” scope=“prototype” /><bean id=“example” class =“spring.MyExample” scope=“myScope” />

In Spring 1.0,<bean id=“example” class=“spring.MyExample” singleton=“false” />

Bean Scopes

4040July 27, 2008

Spring Framework

Scopes available,singletonprototyperequestsessionglobal sessioncustom scope (since Spring 2.0+)

Bean Scopes

4141July 27, 2008

Spring Framework

Constructor Injection

<bean id=“helloWorldService“ class=“spring.HelloWorldImpl"><constructor-arg>

<value>Hello World!</value></constructor-arg>

</bean>

Strong dependency contractNo superfluous setter’sDependent properties immutable

Setter Injection

<bean id=“helloWorldService“ class=“spring.HelloWorldImpl"><property name=“message">

<value>Hello World!</value></property>

</bean>

Prevents lengthy constructorsSeveral ways to construct an objectMultiple dependencies of same typeConstructors pose a problem in case of inheritance

42

Constructor v/s Setter Injection

July 27, 2008

Spring Framework

Examplepublic class Foo(Bar bar, Car car) {

//…}

<bean name=“Foo” class=“Foo”><constructor-arg><bean class=“Bar” /></constructor-arg><constructor-arg><bean class=“Car” /></constructor-arg>

</bean>

Examplepublic class Example(int years, String name) {

//…}

<bean name=“example” class=“Example”><constructor-arg type=“int” value=“75000” /><constructor-arg type=“java.lang.String” value=“Spring Enabled Message” />

</bean><bean name=“example” class=“Example”>

<constructor-arg index=“0” value=“75000” /><constructor-arg index=“1” value=“Spring Enabled Message” />

</bean>

Constructor Argument Resolution

43July 27, 2008

Spring Framework

Example<bean id=“EmailService” class=“spring.EmailServiceImpl”>

<property name=“loginService”><bean class=“spring.LDAPLoginService” />

</property></bean>

RememberCan not reuse the inner-bean instanceUseful when we want to escape AOP proxying.

Inner Beans

44July 27, 2008

Spring Framework

Four types of auto-wiringbyNameFind a bean whose name is same as the name of the property being wired.

byTypeFind a single bean whose type matches the type of the property being wired. If more than one bean is found, UnsatisfiedDependencyException will be thrown.

constructorMatch one or more beans in the container with the parameters of one of the constructors of the bean being wired.

autodetectAutowire by constructor first, then byType.

Auto Wiring

4545July 27, 2008

Spring Framework

<bean id=“pricingService” class=“….”><property name=“pricingDao”>

<ref bean=“pricingDao” /></property><property name=“ssnService”>

<ref bean=“ssnService></property>

</bean>

By Name<bean id=“pricingService” class=“…” auto-wire=“byName” />

By Type<bean id=“pricingService” class=“…” auto-wire=“byType” />

Auto Wiring - Examples

4646July 27, 2008

Spring Framework

Mixing auto and explicit wiring<bean id=“pricingService” class=“…” autowire=“byName” >

<property name=“ssnService”><ref bean=“newSSNService” />

</property></bean>

By-default wiring<beans default-autowire=“byName” >

Can pose problems while refactoring if,Bean cannot be foundBean is not the one, the service actually wants

Auto Wiring - Advanced

4747July 27, 2008

Spring Framework

Four types of dependency checks,noneProperties that have no value are not set.

simplePerformed for primitive types and collections, except collaborators.

objectPerformed only for collaborators.

allPerformed for primitives, collections and colloborators.

Dependency Check

4848July 27, 2008

Spring Framework

Specifying<bean id=“myBean” class=“…” lazy-init=“true” />

By default lazy initialization<beans default-lazy-init=“true”>

…. // various bean definitions</beans>

Lazy Initialization

4949July 27, 2008

Spring Framework

Example

public class Example {public void setup() {

//init method}public void tearDown() {

//destruction}//…

}

<bean id=“example” class=“Example” init-method=“setup” destroy-method=“tearDown” />

Custom init & destroy

50July 27, 2008

Spring Framework

Using a static factory method<bean id=“myBean” class=“spring.MyClass” factory-method=“createInstance” />

Using an instance factory method<bean id=“myFactoryBean” class=“spring.MyFactory” />

<bean id=“myBean” factory-bean=“myFactoryBean” factory-method=“createInstance” />

Factory Beans

51July 27, 2008

Spring Framework

Wiring lists,<bean id=“myObject” class=“spring.complexObject” >

<property name="listProperty"> <list> <value>a list element</value> <ref bean="otherBean"/> <ref bean="anotherBean"/>

</list></property>

</bean>

Collections – java.util.List

52July 27, 2008

Spring Framework

Wiring sets,<bean id=“myObject” class=“spring.complexObject” >

<property name="listProperty"> <set> <value>a list element</value> <ref bean="otherBean"/> <ref bean="anotherBean"/>

</set></property>

</bean>

Collections – java.util.Set

5353July 27, 2008

Spring Framework

Wiring maps,<bean id=“myObject” class=“spring.complexObject” >

<property name="mapProperty"><map> <entry key=“firstEntry">

<value>just some string</value> </entry> <entry> <key>

<value>some key</value> </key>

<ref bean="otherBean"/> </entry></map>

</property></bean>

Collections – java.util.Map

5454July 27, 2008

Spring Framework

Wiring properties,<bean id=“myObject” class=“spring.complexObject” >

<property name=“propsProperty"><props> <prop key=“user”>sandeep</prop> <prop key=“org”>Headstrong</prop></props>

</property></bean>

* The values of a map key, map value or a set key, can again be any of the following,

bean | ref | idref | list | set | map | props | value | null

Collections – java.util.Properties

5555July 27, 2008

Spring Framework

Supported in Spring 2.0+<bean id=“parent” class=“spring.ParentBean” abstract=“true”>

<property name=“propsProperty"> <props> <prop key=“user”>sandeep</prop> <prop key=“org”>Headstrong</prop> </props>

</property></bean>

<bean id=“child” parent=“parent” ><property name=“propsProperty”>

<props> <prop key=“email”>sandy.pec@gmail.com</prop>

</props></property>

</bean>

Collections – Merging

5656July 27, 2008

Spring Framework

Wiring null values<property name=“middleName”><null /></property>

Null Values

57July 27, 2008

Spring Framework

Promotes reuse of bean instances,<ref bean=“someBean” /><ref local=“localBean” />

In parent-child context,<!-- in the parent context --><bean id=“parentBean” class=“spring.ParentBean” />

<!-- in the child context --><bean id=“parentBean” class=“spring.proxy.ParentBeanProxy” > <!-- the bean name is same -->

<property name=“target”> <ref parent=“parentBean” /></property>

</bean>

Referencing Beans

5858July 27, 2008

Spring Framework

Forces check at deployment time<bean id=“targetBean” class=“spring.TargetBean” />

<bean id=“clientBean” class=“spring.ClientBean” ><property name=“targetBean” value=“targetBean” />

</bean>

convert to,<bean id=“clientBean” class=“spring.ClientBean” >

<property name=“targetBean”> <idref bean=“targetBean” /></property>

</bean>

idref

5959July 27, 2008

Spring Framework

Normal Spring metadata<bean id=“dataSource” class=“…”>

<property name=“url” value=“jdbc:hsqldb:myDatabase” /><property name=“driverClassName” value=“org.hsqldb.jdbcDriver” /><property name=“userName” value=“appUser” /><property name=“password” value=“appPass” />

</bean id>

Converting to properties<bean id=“dataSource” class=“…”>

<property name=“url” value=“${database.url}” /><property name=“driverClassName” value=“${database.driver}” /><property name=“userName” value=“{database.user}” /><property name=“password” value=“${database.password}” />

</bean id>

defined in a properties file,database.url=jdbc:hsqldb:myDatabasedatabase.driver=org.hsqldb.jdbcDriverdatabase.user=appUserdatabase.password=appPass

i18N & Spring

60July 27, 2008

Spring Framework

Load the property file configurer

<bean id=“propertyConfigurer” class=“org.springframework.beans.factory.config.PropertyPlaceholderConfigurer”><property name=“locations”>

<value>jdbc.properties</value><value>security.properties</value><value>logging.properties</value>

</property></bean id>

i18N & Spring

61July 27, 2008

Spring Framework

Penetration of OOP ;)

<bean id=“abstractBean” class=“spring.AbstractBean” abstract=“true” ><property name=“name” value=“spring” /><property name=“version” value=“2.5” />

</bean>

Inherit properties,<bean id=“inheritedBean” parent=“abstractBean” class=“spring.ImplementedAbstractBean />

Overriding properties,<bean id=“inheritedBean” parent=“abstractBean” class=“spring.ImplementedAbstractBean >

<property name=“name” value=“spring framework” /></bean>

Bean Inheritance

6262July 27, 2008

Spring Framework

Created by implementing certain interfaces, and can be used to

become involved in bean life-cycleload configuration from external property filesalter Spring’s dependency injection to automatically convert String values to desired objectsload text messages, say internationalized messageslisten to and respond to eventsmake beans aware of their identity inside Spring container

Special Beans

63July 27, 2008

Spring Framework

Events handled by ApplicationContextContextClosedEventContextRefreshedEventRequestHandledEvent

To respond, beans must implement the ApplicationListener interfacepublic class RefreshListener implements ApplicationListener {

public void onApplicationEvent(ApplicationEvent event) {//…

}}

<bean id=“refreshListener” class=“RefreshListener” />

Events

64July 27, 2008

Spring Framework

Define an eventpublic class MyEvent extends ApplicationEvent {

private String str;public MyEvent(Object source, String anyParam) {

super(source);this.str = anyParam;

}public String getStr() {

return this.str;}

}

Raise the eventApplicationContext context = …;String param = //anything that we need to pass to the event;context.publishEvent(new MyEvent(this, param));

Raising custom Events

65July 27, 2008

Spring Framework

Implement the interface,org.springframework.beans.factory.config.Scope

Object get(String name, ObjectFactory objectFactory)Object remove(String name)void registerDestructionCallback(String name, Runnable destructionCallback)String getConversationId()

Custom Scope

6666July 27, 2008

Spring Framework

<bean class=“org.springframework.beans.factory.config.CustomScopeConfigurer” ><property name=“scopes” >

<map> <entry key=“thread”>

<bean class=“spring.scope.ThreadScope” /> </entry>

</map></property>

</bean>

Usage,<bean id=“myBean” class=“spring.MyBean” scope=“thread” />

Custom Scope - gluing

6767July 27, 2008

Spring Framework

04 AOP in Detail

68July 27, 2008

Spring Framework

AspectModularization of a concern/cross-cutting functionality

Join PointPoint during the execution of a program where an aspect is plugged in

AdviceAction taken at a particular Join Point

Point CutSet of Join Points specifying when an advice should be woven

IntroductionAdding new methods or fields to an existing class

TargetClass that is being advised

ProxyObject created after applying advice

WeavingProcess of applying aspects to target object to create new proxy objectsCan take place at several points during a class lifetime

Compile Time: Requires special compiler.Classload TimeRunTime

AOP lingua-franca

69July 27, 2008

Spring Framework

Spring advice is written in Java*It advises objects only at runtime

If our class implements the required interface, proxies are generated using java.lang.reflect.Proxy class. Favored for results in more loosely coupled application.If it does not, it uses CGLIB to generate subclass proxies

Implements AOP Alliance interfacesResuable code with other compatible AOP frameworks

Supports only method joinpointsFrameworks such as AspectJ, JBoss support field joinpoints too

Spring & AOP

70July 27, 2008

Spring Framework

Types of advice offered by SpringBeforeCalled before the target method is invoked

After (returning)Called after the invocation of the target method which returns normally.

(After) ThrowsCalled when target method throws an exception

After (finally) *Called when target method is invoked, no matter how it returns.

AroundIntercepts calls to the target method

IntroductionUsed to build composite objects

Advice

71July 27, 2008

Spring Framework

Implement the MethodBeforeAdvicepublic interface MethodBeforeAdvice {

void before(Method method, Object[] args, Object target) throws Throwable}

public class WelcomeAdvice implements MethodBeforeAdvice {public void before(Method method, Object[] args, Object target) throws Throwable {

Customer cust = (Customer) args[0];System.out.println(“Hello “ + cust.getName() );

}}

<bean id=“myTarget” class=“spring.EmailInboxImpl” /><bean id=“welcomeAdvice” class=“spring.advice.WelcomeAdvice” />

<bean id=“inbox” class=“org.springframework.aop.framework.ProxyFactoryBean”><property name=“proxyInterfaces” value=“spring.EmailInbox” /><property name=“interceptorNames”>

<list><value>welcomeAdvice</value></list></property><property name=“target” ref=“myTarget” />

</bean>

BeforeAdvice

72July 27, 2008

Spring Framework

Implement the AfterReturningAdvicepublic interface AfterReturningAdvice {

void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable}

public class ThankYouAdvice implements AfterReturningAdvice { void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {

System.out.println(“Thanks.“);}

}

<bean id=“myTarget” class=“spring.LogOutImpl” /><bean id=“thankYouAdvice” class=“spring.advice.ThankYouAdvice” /><bean id=“inbox” class=“org.springframework.aop.framework.ProxyFactoryBean”>

<property name=“proxyInterfaces” value=“spring.LogOut” /><property name=“interceptorNames”>

<list><value>thankYouAdvice</value></list></property><property name=“target” ref=“myTarget” />

</bean>

AfterAdvice

73July 27, 2008

Spring Framework

Implement the ThrowsAdvice interface

public interface ThrowsAdvice {void afterThrowing(Throwable throwable);

void afterThrowing(Method method, Object[] args, Object target, Throwable throwable);}

* Must implement atleast one method of the two signatures

ThrowsAdvice

74July 27, 2008

Spring Framework

Implement the MethodInterceptor interface

Controls whether the actual target method is actually invokedGives control over the return value

public interface MethodInterceptor {public Object invoke(MethodInvocation invocation);

}

public class MyInterceptor implements MethodInterceptor {public Object invoke(MethodInvocation invocation) {

//do something before the method invocationObject returnValue = invocation.proceed();//do something after the method invocation

return someReturnValue;}

}

AroundAdvice

75July 27, 2008

Spring Framework

Implement the IntroductionInterceptor interface

build composite objects, adding new methods/attributes to the advised classpublic class AuditableMixin implements IntroductionInterceptor, Auditable {

public boolean implementsInterface(Class intf) {return intf.isAssignableFrom(Auditable.class);

}

public Object invoke(MethodInvocation m) throws Throwable {if (implementsInterface(m.getMethod().getDeclaringClass())) { return m.getMethod().invoke(this, m.getArguments());} else { return m.proceed();}

}

private Date lastModifiedDate;public Date getLastModifiedDate() { .. }public void setLastModifiedDate(Date lastModifiedDate) { … }

}

Introductions

76July 27, 2008

Spring Framework

Implement the PointCut interface

public interface Pointcut {ClassFilter getClassFilter();MethodMatcher getMethodMatcher();

}

public interface ClassFilter {boolean matches(Class clazz);

}

public interface MethodMatcher {boolean matches(Method m, Class targetClass);boolean matches(Method m, Class targetClass, Object[] args);boolean isRuntime();

}

PointCut

77July 27, 2008

Spring Framework

NameMatchMethodPointcut<bean id=“orderMethodPointcut“

class="org.springframework.aop.support.NameMatchMethodPointcut"><property name="mappedName“ value=“order*” />

</bean>

RegexpMethodPointCut: Matches a Perl5 regex to a fully qualified method name

<bean id=“beanMethodsPointcut“ class="org.springframework.aop.support.RegexpMethodPointcut"><property name=“patterns“>

<list> <value>.*\.get.*</value> <value>.*\.set.*</value></list>

</property></bean>

PointCut Implementation

78July 27, 2008

Spring Framework

Aspect’s as a combination of an Advice and a Pointcut.Each built in Advice has an AdvisorExample<bean id="debugInterceptor" class="DebugInterceptor"/>

<bean id=“debugAdvisor" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"><constructor-arg ref="debugInterceptor"/><property name="pattern“ value=“.*\.get.*” />

</bean>

<bean id=“myTarget” class=“spring.MyServiceImpl” />

<bean id=“myService” class=“org.springframework.aop.framework.ProxyFactoryBean”><property name=“proxyInterfaces” value=“spring.MyService” /><property name=“interceptorName” value=“debugAdvisor” /><property name=“target” value=“myTarget” />

</bean>

Spring Advisors

79July 27, 2008

Spring Framework

Enables Spring container to generate proxies for usImplemented using,

BeanNameAutoProxyCreator: Apply aspect uniformly over a set of beans

DefaultAdvisorAutoProxyCreator: Apply advisors uniformly over a set of beans

Auto Proxy

80July 27, 2008

Spring Framework

BeanNameAutoProxyCreator

<bean id=“performanceProxyCreator” class=“org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator” ><property name=“beanNames”>

<list> <value>*Service<value> <value>*DAO<value><list>

</property><property name=“interceptorNames” value=“myPerformanceInterceptor” />

</bean>

Auto Proxy Examples

81July 27, 2008

Spring Framework

DefaultAdvisorAutoProxyCreator

<bean id=“advisor” class=“org.springframework.aop.support.RegexpMethodPointcutAdvisor”><property name=“advice” ref=“myPerformanceInterceptor”><property name=“pattern” value=“.+Service\..+” />

<bean>

<bean id=“performanceProxyCreator” class=“org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator” ><property name=“interceptorNames” value=“myPerformanceInterceptor” />

</bean>

Auto Proxy Examples

82July 27, 2008

Spring Framework

05 Bean Lifecycle

83July 27, 2008

Spring Framework

In Bean Factory Container

84

Instantiate

Populate Properties

BeanNameAware’ssetBeanName()

BeanFactoryAware’ssetBeanFactory()

Pre-initializationBeanPostProcessors

InitializingBean’safterPropertiesSet()

Call custom init-method

Post-initializationBeanPostProcessors

Disposable Bean’s destroy()

Call custom destroy-method

Bean is ready to use

Container is shutdown

July 27, 2008

Spring Framework

In Application Context

85

Instantiate

Populate Properties

BeanNameAware’ssetBeanName()

BeanFactoryAware’ssetBeanFactory()

Pre-initializationBeanPostProcessors

InitializingBean’safterPropertiesSet()

Call custom init-method

Post-initializationBeanPostProcessors

Disposable Bean’s destroy()

Call custom destroy-method

Bean is ready to use

Container is shutdown

ApplicationContextAware’ssetApplicationContxet()

July 27, 2008

Spring Framework

Not applicable for web applications – hooks are already in place for Spring’s web-based ApplicationContext

public static void main(String[] args) {AbstractApplicationContext ctx = new …

// add a shutdown hookctx.registerShutdownHook();

}

Graceful Shutdown

8686July 27, 2008

Spring Framework

Self Aware Beans – that handle the Spring container themselves, and may control the container’s behavior

Three ways to make beans aware,BeanNameAwareBeanFactoryAwareApplicationContextAware

Knowing Who You Are

8787July 27, 2008

Spring Framework

BeanNameAwarepublic interface BeanNameAware {

void setBeanName(String name);}

BeanFactoryAwarepublic interface BeanFactoryAware {

void setBeanFactory(BeanFactory factory);}

ApplicationContextAwarepublic interface ApplicationContextAware {

void setApplicationContext(ApplicationContext context);}

Creating Self Aware Beans

8888July 27, 2008

Spring Framework

06 Extensibility

8989July 27, 2008

Spring Framework

Mechanism for schema-based extensions to the base Spring XML format for definining and configuring beans

Authoring an XML SchemaCoding a custom NamespaceHandler implementationCoding one or more BeanDefinitionParser implementationsGluing the above into Spring

Extensibility?

9090July 27, 2008

Spring Framework

Element <myns:dateFormat /> for SimpleDateFormat objects.

<myns:dateFormat id=“myDate” pattern=“yyyy-MM-dd HH:mm” lenient=“true” />

analogous to,<bean id=“dateFormat” class=“java.text.SimpleDateFormat”>

<constructor-arg value=“yyyy-MM-dd HH:mm” /><property name=“lenient” value=“true” />

</bean>

Extensibility Example

9191July 27, 2008

Spring Framework

<?xml version="1.0" encoding="UTF-8"?><xsd:schema xmlns="http://www.springframework.org/schema/myns" xmlns:xsd="http://www.w3.org/2001/XMLSchema“ xmlns:beans="http://www.springframework.org/schema/beans" targetNamespace="http://www.mycompany.com/schema/myns" elementFormDefault="qualified" attributeFormDefault="unqualified">

<xsd:import namespace="http://www.springframework.org/schema/beans"/> <xsd:element name="dateformat"> <xsd:complexType> <xsd:complexContent> <xsd:extension base="beans:identifiedType"> <xsd:attribute name="lenient" type="xsd:boolean"/> <xsd:attribute name="pattern" type="xsd:string" use="required"/> </xsd:extension> </xsd:complexContent> </xsd:complexType> </xsd:element></xsd:schema>

Authoring Schema

9292July 27, 2008

Spring Framework

Helps parse all elements in the new namespaceNamespaceHandler

init()called before the handler is used

BeanDefinition parse(Element, ParserContext)called when Spring encounters a top-level element

BeanDefinitionHolder decorate(Node, BeanDefinitionHolder,ParserContext)

called when Spring encounters an attribute or nested element of a different namespace

Namespace Handler

9393July 27, 2008

Spring Framework

NamespaceHandlerSupport

package spring.xml;

import org.springframework.beans.factory.xml.NamespaceHandlerSupport;

public class MyNamespaceHandler extends NamespaceHandlerSupport { public void init() { registerBeanDefinitionParser("dateformat", new SimpleDateFormatBeanDefinitionParser()); }}

NamespaceHandler

9494July 27, 2008

Spring Framework

public class SimpleDateFormatBeanDefinitionParser extends AbstractSingleBeanDefinitionParser {

protected Class getBeanClass(Element element) { return SimpleDateFormat.class; }

protected void doParse(Element element, BeanDefinitionBuilder bean) { // this will never be null since the schema explicitly requires that a value be supplied String pattern = element.getAttribute("pattern"); bean.addConstructorArg(pattern);

// this however is an optional property String lenient = element.getAttribute("lenient"); if (StringUtils.hasText(lenient)) { bean.addPropertyValue("lenient", Boolean.valueOf(lenient)); } }}

Bean Definition Parser

9595July 27, 2008

Spring Framework

Place the following property files in the META-INF directory in root

spring.handlersmapping of XML schema URI to namespace handler classes

http\://www.mycompany.com/schema/myns=org.springframework.samples.xml.MyNamespaceHandler

spring.schemasmapping of XML schema location to classpath resources

http\://www.mycompany.com/schema/myns/myns.xsd=org/springframework/samples/xml/myns.xsd

Register Handler/Parser

9696July 27, 2008

Spring Framework

<beans><!-- as a top-level bean --><myns:dateformat id="defaultDateFormat" pattern="yyyy-MM-dd HH:mm" lenient="true"/>

<bean id=“someBean" class=“spring.SomeBean” ><property name="dateFormat"> <!-- as an inner bean --> <myns:dateformat pattern="HH:mm MM-dd-yyyy"/></property>

</bean></beans>

Usage

9797July 27, 2008

Spring

The Beginning…

9898July 27, 2008

Spring Universe

SpringSource Application Platform

99

Enterprise Bundle Repository

Spring Dynamic Kernel Mode

• Real time server Updates• Side-by-side Resource Versioning• Run old & new applications• Smaller server footpriint• Inject Bundles at runtime

Applications

JARs

Tomcat

Spring Personalities

Eclip

se E

quin

ox(O

SGi)

Logging Subsystem Tracing Subsystem Exception Detection/Reporting

99July 27, 2008

Spring Universe

Spring WebFlowProvides infrastructure for building and running RIA, builds over Spring MVC

Spring Web ServicesHelps create document-driven Webservices, facilitates contract-first SOAP service deployment.

Spring Security (aka Acegi)Security Solution for web applications – supports JSR 250 (EJB3), ACL, SiteMinder, CAS3, Portlets, Webflow, OpenID, Windows NTLM and more.

Spring Dynamic Modules for OSGi Services PlatformHelps build Spring applications that can run in an OSGi platform with better separation of modules.

Spring BatchFramework for development of robust batch applications using POJOs.

Other Spring Projects

100100July 27, 2008

Spring Universe

Spring IntegrationAn extension of Spring model to support Enterprise Integration Patterns.

Spring LDAPLibrary for Java based LDAP operations based on Spring’s Template pattern.

Spring IDEGUI for working with Spring configuration files over Eclipse.

Spring ModulesA collection of modules, add-ons and integration tools for Spring, like Ant, Flux, HiveMind, Lucene, O/R Broker, OSWorkflow, Tapestry, EHCache, OSCache, GigaSpaces, db4o, Drools, Jess, Groovy, Velocity, Jackrabbit, Jeceira and many many more…

Spring Java ConfigProvides pure-Java, type-safe option for configuring Spring Contexts.

Other Spring Projects

101101July 27, 2008

Spring Universe

Spring BeanDocTool for documenting and graphing Spring bean factories and context files.

Spring RCPPlatform to construct rich Swing applications. Analogous to Eclipse RCP.

Grid Gain*A grid-computing platform in Java which is a natural extension of development methodologies including annotations, Spring dependency injection, and AOP-based grid-enabling.

Other Spring Projects

102102July 27, 2008

Other Framework’s

AvalonSupports Service Locator & Interface Injection, but is intrusive.

Google GuiceAll configuration is in Java, reduces a lot of boiler plate, and can be up to 50x faster than Spring.

HiveMindIs more of a component based registry provider.

PicoContainer & NanoContainerVery lightweight (~50kb) but supports only Singletons.

EJB 3 (such as JBoss Seam)Is a standard and comes as a whole package.

Naked ObjectsMay be used in conjunction.

Dependency Injection

103103July 27, 2008

Other Framework’s

AspectJCompile team weaving, supports field joinpoints. Spring 2.0+ complements AspectJ. Aspects not in Java

JBoss AOPComes with pre-packaged aspects such as caching, asynchronous communication, security, remoting…

AspectWerkzSimilar to AspectJ with Aspects written in Java.

Object TeamsA new entrant to AOP world, visits the concepts of Teams/Modules on a set of role objects.

DynaopQuite old, doesn’t offers much, but, is damn fast (up to 5x faster than Spring)

For better comparison, visit http://www.ibm.com/developerworks/library/j-aopwork1/

AOP

104104July 27, 2008

Spring Framework

References & Feedback

105July 27, 2008

Spring Framework

Websiteshttp://www.springframework.orghttp://martinfowler.com/articles/injection.htmlhttp://docs.codehaus.org/display/PICO/Inversion+of+Controlhttp://static.springframework.org/spring/docs/2.5.5/reference/index.htmlhttp://www.theserverside.com/articles/article.tss?l=SpringFrameworkhttp://www.ibm.com/developerworks/library/j-aopwork1/

BooksSpring In Action by Craig Walls and Ryan Breidenbach Spring j2ee Application Framework by Spring Development TeamJ2EE Without EJB by Rod Johnson and Juergen HollerSpring Live by Matt Raible

References

106July 27, 2008

Spring Framework

For any queries or suggestions, Post it on,

http://azcarya.googlecode.com

Drop me a mail at,sandy.pec@gmail.com

Questions/Feedback

107July 27, 2008

SANDEEP GUPTAHope this helps.

108July 27, 2008

© 2008, under Creative Commons 3.0 Attribution License