Spring Framework - Core

Spring Framework - Core

SPRING FRAMEWORK 3.0
Dmitry Noskov Spring Core

What is Spring?
Spring is the most popular application development
framework for enterprise Java™. Millions of
developers use Spring to create high performing,
easily testable, reusable code without any lock-in.

Spring Framework - Core Dmitry Noskov

The Spring projects

Spring
MVC

Spring Spring
Social WebFlow

Spring Spring
Batch Security
Spring
Framework

Spring Spring
Data Integration

Spring
Web
And
Services …


Overview
History
Goals
Spring modules
Spring triangle


Spring Framework history(1)
 the first version was written by Rod Johnson
 Expert One-on-One J2EE Design and Development
 first released in June 2003
 milestone releases in 2004 and 2005
 awards
 Jolt productivity award
 JAX Innovation award


Spring Framework history(2)
 Spring 3.0 (released Dec 2009)
 Java 1.5+
 REST support, SpEL, more annotations, JavaConfig

 Spring 2.5 (released Nov 2007)
 Java 1.4+
 XML namespaces, annotations

 Spring 2.0 (released Oct 2006)
 Java 1.3+
 AspectJ support, JPA


Goals
 make J2EE easier to use
 make the common tasks easier
 promote good programming practice
 you can focus on the domain problems


What is Spring Framework today?
 an open source application framework
 a lightweight solution for enterprise applications
 non-invasive (POJO based)
 is modular
 extendible for other frameworks
 de facto standard of Java Enterprise Application


Spring modules


Core container
 Core and Beans
provide the fundamental parts of the framework, including IoC and Dependency
Injection features

 Context
it is a means to access objects in a framework-style manner that is similar to a JNDI
registry

 Expression language
provides a powerful expression language for querying and manipulating an object
graph at runtime


AOP, Aspect, Instrumentation
 AOP
provides an AOP Alliance-compliant aspect-oriented programming implementation
allowing you to define, for example, method-interceptors and pointcuts to cleanly
decouple code that implements functionality that should be separated

 Aspect
provides integration with AspectJ

 Instrumentation
provides class instrumentation support and classloader implementations to be used in
certain application servers


Data Access/Integration
 JDBC - provides a JDBC-abstraction layer
 ORM - provides integration layers for popular object-relational mapping APIs,
including JPA, JDO, Hibernate and iBatis

 OXM - provides an abstraction layer that supports Object/XML mapping
implementations for JAXB, Castor, XMLBeans, JiBX and XStream.

 JMS – contains features for producing and consuming messages.
 Transaction - supports programmatic and declarative transaction
management


WEB
 Spring’s WEB
provides basic web-oriented integration features

 WEB-Servlet
Spring’s model-view-controller (MVC) implentation

 WEB-Struts
contains the classes for integrating a classic Struts WEB tier within a Spring application

 WEB-Portlet
provides the MVC implementation to be used in a portlet environment


Full-fledged Spring web application


Using a third-party web framework


Remoting


EJB


The Spring triangle


Spring IoC container
IoC pattern
Application lifecycle
Essence of Spring IoC container
Instantiation an ApplicationContext


What is IoC?
 is a concept in application development
 "don’t call me, I’ll call you"
 one form is Dependency Injection (DI)


Dependency Injection
 is a process whereby objects define their
dependencies, that is, the other objects they work
with, only through constructor arguments, arguments
to a factory method, or properties that are set on
the object instance after it is constructed or returned
from a factory method
 exist in two major variants
1) constructor injection
2) setter injection

IoC vs DI vs Factory
 DI it is specific type of IoC

 The Factory pattern’s main concerns is creating
 The DI’s main concern is how things are connected
together

 DI related to Factory and Strategy patterns, but
mostly resembles to Build Pattern


Application lifecycle

Initialization Use Destruction

• creating • process • shuts
services requests down
• allocate • 99% of • release
resources the time resources


Essence of IoC container


Terms
 ApplicationContext
 represents the Spring IoC container
 bean
 is an object that managed by Spring IoC container
 BeanDefinition
 describe a bean instance


Context lifecycle

Load BFPP Instantiation Property BPP Ready
definitions injection to use


Bean lifecycle


Creating application context
 environments
 standalone
 WEB

 JUnit

 EJB

 special prefixes
 classpath
 file system

 relative path


Instantiation for standalone
 ClassPathApplicationContext
 FileSystemApplicationContext
ApplicationContext context =
new ClassPathXmlApplicationContext(
new String[] {"services.xml", "repositories.xml"});

// retrieve configured instance
CurrencyService currencyService
= context.getBean("currency", CurrencyService.class);

AccountService accountService
= context.getBean(AccountService.class);


Instantiation for WEB applications

Servlet 2.4+ Servlet 2.3
<context-param>
<servlet>
<param-name>
contextConfigLocation <servlet-name>
</param-name>
context
<param-value>
/WEB-INF/daoContext.xml </servlet-name>
/WEB-INF/applicationContext.xml
<servlet-class>
</param-value>
org.springframework.web.context.ContextLoaderServlet
</context-param>
</servlet-class>
<listener>
<load-on-startup>1
<listener-class>
org.springframework.web.context.ContextLoaderListener </load-on-startup>
</listener-class>
</servlet>
</listener>


Bean Scope
Simple
Runtime
WEB
CGLIB / JDK proxies


Spring Bean Scopes
 simple
 singleton
 prototype
 runtime
 thread
 custom implementation
 web-aware scopes (available only for web-aware ApplicationContext)
 request
 session
 global session


The singleton scope


The prototype scope


Custom scope

public interface org.springframework.beans.factory.config.Scope {
//Return the object with the given name from the underlying scope
Object get(String name, ObjectFactory<?> objectFactory);

//Remove the object with the given name from the underlying scope.
Object remove(String name);

//Register a callback to be executed on destruction of the specified object
void registerDestructionCallback(String name, Runnable callback);

//Resolve the contextual object for the given key, if any.
Object resolveContextualObject(String key);

//Return the conversation ID for the current underlying scope, if any.
String getConversationId();
}


Using runtime scope
<bean class="org.springframework.beans.factory.config.CustomScopeConfigurer">
<property name="scopes">
<map>
<entry key="thread">
<bean class="org.springframework.context.support.SimpleThreadScope"/>
</entry>
</map>
</property>
</bean>

<bean id="threadService" class="example.ThreadServiceImpl" scope="thread">
<property name="priority" value="0"/>
<aop:scoped-proxy/>
</bean>

<bean id="threadMonitor" class="example.ThreadMonitorImpl">
<property name="threadService" ref="thredService"/>
</bean>


Scoped bean as dependencies

Using CGLIB library (by default)
<bean id="preferences" class="UserPreferences" scope="session">
<aop:scoped-proxy/>
</bean>
<bean id="userManager" class="example.UserManager">
<property name="userPreferences" ref="preferences"/>
</bean>

Using JDK interface based proxies means
<bean id="preferences" class="UserPreferences" scope="session">
<aop:scoped-proxy proxy-target-class="false"/>
</bean>
<bean id="userManager" class="example.UserManager">
<property name="userPreferences" ref="preferences"/>
</bean>


WEB-aware scope configuration

Servlet 2.4+ Servlet 2.3
<web-app> <web-app>
<listener> <filter>
<filter-name>filter</filter-name>
<listener-class>
<filter-class>
org.springframework.web.context.request.
RequestContextListener …web.filter.RequestContextFilter
</listener-class> </filter-class>
</listener> </filter>
</web-app> <filter-mapping>
<filter-name>filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>


XML-based configuration
Configuration
Main features
Bean lifecycle
Additional features


Namespaces
<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<bean id="" class=""></bean>

<bean id="" class=""/>
</beans>


BeanFactoryPostProcessor

public interface BeanFactoryPostProcessor {

/**
* Modify the application context's internal bean factory after its standard
* initialization. All bean definitions will have been loaded, but no beans
* will have been instantiated yet. This allows for overriding or adding
* properties even to eager-initializing beans.
* @param beanFactory the bean factory used by the application context
* @throws org.springframework.beans.BeansException in case of errors
*/
void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory);
}


Instantiating bean


Naming beans

<beans>
<bean id="beanId" class="org.exhanger.api.OrderServiceImpl"/>

<bean name="name/" class="org.exhanger.api.OrderServiceImpl"/>

<bean name="name1,name2;name3 name4" class="...">
</bean>

<alias name="fromName" alias="toName"/>
</beans>


Instantiating bean
 with a constructor
 with a static factory method
 using an instance factory method
 with the FactoryBean


Instantiating with a constructor
 simple class
<bean id="exampleBean" class="examples.ExampleBean"/>
public class ExampleBean {
public ExampleBean() {}
}

 inner class
<bean id="innerBean" class="examples.ExampleBean$InnerBean"/>
public class ExampleBean {
public static class InnerBean {
}
}


Instantiating with a static method

<bean id="clientService" class="examples.ClientService"
factory-method="createInstance"/>

public class ClientService {
private static ClientService clientService = new ClientService();

private ClientService() {}

public static ClientService createInstance() {
return clientService;
}
}


Using an instance factory method

<bean id="serviceLocator" class="example.ServiceLocator"/>

<bean id="clientService"
factory-bean="serviceLocator"
factory-method="createClientServiceInstance"/>

public class ServiceLocator {
private static ClientService clientService = new ClientService();

public ClientService createClientServiceInstance() {
return clientService;
}
}

Instantiating with the FactoryBean
public interface FactoryBean<T> {
/**Return an instance of the object managed by this factory.*/
T getObject() throws Exception;

/** Return the type of object that this FactoryBean creates.*/
Class<?> getObjectType();

/**Is the object managed by this factory a singleton? */
boolean isSingleton();
}

<bean id="bean" class="FactoryBean"/>


Dependency injection


Constructor-based DI
 is accomplished by the container invoking a
constructor with a number of arguments, each
representing a dependency
 calling a static factory method with specific
arguments to construct the bean is nearly equivalent


Constructor argument resolution
 argument resolution
<bean id="b1" class="org.examples.ClientServiceBean">
<constructor-arg ref="b2"/>
<constructor-arg ref="b3"/>
</bean>

 argument type matching
<bean id="b2" class="ClientService" factory-method="getInstance">
<constructor-arg type="int" value="7500000"/>
<constructor-arg type="java.lang.String" value="42"/>
</bean>

 argument index
<bean id="b3" factory-bean="factory" factory-method="getInstance"/>
<constructor-arg index="0" value="75"/>
<constructor-arg index="1" value="42"/>
</bean>


Setter-based DI
 is accomplished by the container calling setter
methods on your beans after invoking a no-
argument constructor or no-argument static factory
method to instantiate bean


Constructor vs setter
 constructor
 mandatory dependencies
 immutability

 setter
 optional dependencies and default values
 obvious names

 auto inheritance


Straight values

<bean id="dataSource"
class="org.apache.commons.dbcp.BasicDataSource" >


<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url">
<value>jdbc:mysql://localhost:3306/mydb</value>
</property>
<property name="username" value="root"/>
<property name="password" value="masterkaoli"/>
</bean>

Null and empty values

<bean class="Bean">
<property name="email" value=""/>
</bean>


<bean class="Bean">
<property name="email"><null/></property>
</bean>

properties

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations" value="classpath:jdbc.properties"/>
</bean>

<bean id="dataSource" destroy-method="close"
class="org.apache.commons.dbcp.BasicDataSource">
<property name="driverClassName" value="${jdbc.driverClass}"/>
<property name="url" >
<value>${jdbc.url}</value>
</property>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>


idref
bean
<bean id="theTargetBean" class="..."/>

<bean id="theClientBean" class="...">
<property name="targetName">
<idref bean="theTargetBean" />
</property>
</bean>

local
<property name="targetName">

<idref local="theTargetBean"/>
</property>

Reference to other bean
 bean
<ref bean="someBean"/>

 local
<ref local="someBean"/>

 parent

<bean id="accountService" class="com.foo.SimpleAccountService"/>


<bean id="accountService" class="org.springframework.ProxyFactoryBean">
<property name="target">
<ref parent="accountService"/>
</property>
</bean>

Inner bean

<bean id="orderService" class="OrderServiceImpl">
<property name="repository" ref="orderRepository"/>
<property name="builder">
<bean class="OrderBuilderImpl">
<constructor-arg ref="accountService"/>
<constructor-arg ref="currencyService"/>
</bean>
</property>
</bean>


Collections(1)

<property name="adminEmails">
<props>
<prop key="administrator">administrator@gmail.com</prop>
</props>
</property>

<property name="someList">
<list>
<value>a list element followed by a reference</value>
<ref bean="myDataSource" />
</list>
</property>

Collections(2)

<property name="someMap">
<map>
<entry key="an entry" value="just some string"/>
<entry key ="a ref" value-ref="myDataSource"/>
</map>
</property>

<property name="someSet">
<set>
<value>just some string</value>
<ref bean="myDataSource" />
</set>
</property>

p namespace
xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd" >

<bean id="orderService" class="OrderServiceImpl"
p:repository-ref="orderRepository"
p:locaton="BY"/>

</beans>


util namespace
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.0.xsd">

</beans>


util in action
<property name="isolation">
<util:constant static-field="java.sql.Connection.TRANSACTION_SERIALIZABLE"/>
</property>

<bean id="testBean" class="org.springframework.beans.TestBean">
<property name="age" value="10"/>
</bean>
<util:property-path id="name" path="testBean.age"/>

<util:properties id="" location="classpath:jdbc.properties"/>

<util:list id="emails" list-class=""><value/><value/></util:list>

<util:map id="emails" map-class=""><entry key="" value=""/></util:map>

<util:set id="emails" set-class=""><value></value></util:set>


Additional features
 bean definition inheritance
 importing configuration files
 autowiring
 lazy initialization
 dependency checking


Bean definition inheritance

<!—attribute class is optional 
<bean id="parent" abstract="true" class="AbstractService">
<property name="name" value="parent"/>
<property name="age" value="1"/>
</bean>

<bean id="service" class="ServiceImpl" parent="parent">
<property name="name" value="override it"/>
</bean>


Bean definition inheritance(2)
<bean id="parent" abstract="true">
<property name="name" value="parent"/>
</bean>

<bean id="default" class="DefaultServiceImpl" parent="parent">
<property name="name" value="default"/>
<property name="value" value="22"/>
</bean>

<bean id="custom" class="CustomServiceImpl" parent="default">
<property name="name" value="custom"/>
</bean>


Importing configuration files
 xml-context-config.xml
<beans>
<import resource="classpath:xml-repository-config.xml"/>
<import resource="classpath:xml-service-config.xml"/>
</beans>

 xml-service-config.xml
<beans>
<bean id="currencyRepository" class="CurrencyMapRepository"/>
</beans>

 xml-repository-config.xml
<bean id="currencyService" class="CurrencyServiceImpl">
<constructor-arg ref="currencyRepository"/>
</bean>


Using depends-on
 can explicitly force one or more beans to be
initialized before the bean using this element is
initialized
<bean id="beanOne" class="ExampleBean"
depends-on="costService,accountDao">
<property name="deviceManager" ref="deviceManager" />
</bean>

<bean id="costService" class="example.service.CostService" />
<bean id="accountDao" class="example.jdbc.JdbcAccountDao" />


Lazy-initialized beans
 IoC container create a bean instance when it is first
requested
<bean id="lazy" class="ExpensiveToCreateBean" lazy-init="true"/>

 control lazy-initialization at the container level
<beans default-lazy-init="true">

</beans>

 disadvantages
 errors in the configuration or surrounding

 environment are detected some time later

Autowiring
 advantages
 can significantly reduce the need to specify properties
or constructor arguments
 can update a configuration as your objects evolve
 disadvantages
 cannot autowire simple properties (primitives)
 autowiring is less exact than explicit wiring

 wiring information may not be available to tools that
may generate documentation from a Spring container


Autowiring modes
 no (default)
 byName
<bean id="messageSource" class="MessageSourceImpl" />
public void setMessageSource(MessageSource messageSource)

 byType
<bean id="messageSource" class="MessageSourceImpl" />
public void setMessageSource(MessageSource messageSource)

 constructor
 autodetect


Dependency checking
 none (default)
 simple

checking for primitive types and collections
 object

checking for collaborators only
 all


Spring Aware Interfaces


Spring aware interfaces
 BeanNameAware
 BeanFactoryAware
 ApplicationContextAware

 ApplicationEventPublisherAware
 ServletConfigAware
 ServletContextAware
 MessageSourceAware


Application events
public class SomeService implements ApplicationContextAware {
public void setApplicationContext(ApplicationContext ctx) {}

public void anyMethod(String value) {
context.publishEvent(new AnyEvent(value));
}
}

public class Listener implements ApplicationListener<AnyEvent> {
public void onApplicationEvent(AnyEvent event) {
}
}


Internationalization
<bean class="org.springframework.context.support.ResourceBundleMessageSource">
<property name="basenames">
<list><value>label</value><value>exceptions</value></list>
</property>
</bean>

public interface MessageSource {
/** Try to resolve the message. Return default if no message was found.*/
String getMessage(String code, Object[] args, String default, Locale locale);

/** Try to resolve the message. Treat an error if the message can't be found.*/
String getMessage(String code, Object[] args, Locale locale);

/** Try to resolve the message using MessageSourceResolvable */
String getMessage(MessageSourceResolvable resorvable, Locale locale);
}


Initialization


BeanPostProcessor
/**
* ApplicationContexts can autodetect BeanPostProcessor beans in their
* bean definitions and apply them to any beans subsequently created. */
public interface BeanPostProcessor {
/**
* Apply this BeanPostProcessor to the given new bean instance before any bean
* initialization callbacks (like afterPropertiesSet or a custom init-method)*/
Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;

/**
* Apply this BeanPostProcessor to the given new bean instance after any bean
* initialization callbacks (like afterPropertiesSet or a custom init-method).
*/
Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;

}


Initialization callbacks
<bean id="bean1" class="exampl.ExampleBean1" init-method="init"/>
public class ExampleBean1 {
public void init() {}
}

<bean id="bean2" class="examples.ExampleBean2"/>
public class ExampleBean2 implements InitializingBean {
public void afterPropertiesSet() {}
}

public class ExampleBean2 {
@PostConstruct
public void initialize() {}
}


Destroy Spring Beans


Destruction callbacks
<bean id="bean1" class="example.Bean1" destroy-method="cleanup"/>
public class Bean1 {
public void cleanup() {}
}

<bean id="bean2" class="example.Bean2"/>
public class Bean2 implements DisposableBean {
public void destroy() {}
}

public class Bean2 {
@PreDestroy
public void destroy() {}
}


Combining lifecycle mechanisms
 initialization methods, are called as follows:
 methods annotated with @PostConstruct
 afterPropertiesSet as defined by InitializingBean
 custom configured init method
 destroy methods are called in the same order:
 method annotated with @PreDestroy
 destroy() as defined by the DisposableBean
 custom configured destroy method


Annotation-based configuration
Basic annotations
Spring stereotypes
JSR-250
JSR-330


Annotation based configuration
 an alternative to XML setups
 annotation injections is performed before XML


Basic annotations(1)
 Spring Annotations
 @Autowired
 @Qualifier
 @Required
 @Value
 JSR 250
 @Resource
 @PostConstruct
 @PreDestroy


Basic annotations(2)
 context
 @Scope
 @Bean
 @DependsOn
 @Lazy
 transactional
 @Transactional


Stereotypical

@Component
Any component

@Repository @Service @Controller @Configuration
Data access Service classes Spring MVC Java Config


Basic configuration


<context:annotation-config/>

<!– scan stereotyped classes and register BeanDefinition -->
<context:component-scan
base-package="org.exhanger.repository.map,org.exhanger.api">

Basic configuration(2)
<context:component-scan
base-package="org.exhanger"
name-generator="my.NameGeneratorImpl"
resource-pattern="**/*.class"
scope-resolver="my.ScopeResolverImpl"
scoped-proxy="no|interfaces|targetClass">

<context:include-filter type="annotation"
expression="org.springframework.stereotype.Service"/>
<context:exclude-filter type="regex"
expression=".*MapRepository"/>

</context:component-scan>


@Value

@Component("authenticationProvider")
public class EjbAuthenticationProvider {

/** The provider api connection url. */
@Value("${provider.api.url}")
private String apiUrl;

/** The provider api connection username. */
private @Value("${provider.api.username}") String apiUsername;

/** The provider api connection password. */
@Value("${provider.api.password}")
private String apiPassword;
}


@Autowired(1)
@Service("accountService")
public class AccountServiceImpl {
@Autowired
private AccountRepository repository;

@Autowired
public AccountServiceImpl(AccountRepository repository) {}

@Autowired(required = false)
public void setRepository(AccountRepository repository) {}

@Autowired
public void populate(Repository r, OrderService s) {}
}


@Autowired(2)
@Service

@Autowired
private AccountRepository[] repositories;

@Autowired
public AccountServiceImpl(Set<AccountRepository> set) {}

@Autowired(required = false)
public void setRepositories(Map<String,AccountRepository> map){
}
}


@Required(1)


@Required
public void setRepository(AccountRepository repository) {}
}

<bean name="accountService" class="AccountServiceImpl">
<property name="repository" ref="accountRepository"/>
</bean>


@Required(2)

@Mandatory
public void setRepository (AccountRepository repository) {}
}

<bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor">
<property name="requiredAnnotationType" value="my.Mandatory"/>
</bean>

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Mandatory {}


@Qualifier
public class ReportServiceImpl {
@Autowired
@Qualifier("main")
private DataSource mainDataSource;

@Autowired
@Qualifier("freeDS")
private DataSource freeDataSource;
}
<beans>
<bean class="org.apache.commons.dbcp.BasicDataSource">
<qualifier value="main"/>
</bean>
<bean id="freeDS" class="org.apache.commons.dbcp.BasicDataSource"/>
</beans>


@Resource
@Resource(name = "orderService")
private OrderService orderService;

@Resource(name = "orderService")
public void setOrderService(OrderService orderService) {}

@Resource
private AuditService auditService;

@Resource
public void setAuditService(AuditService auditService) {}
}


@Scope

@Service
@Scope("prototype")
public class AccountServiceImpl implements AccountService {
}

@Service
@Scope(value = BeanDefinition.SCOPE_PROTOTYPE,
proxyMode = ScopedProxyMode.TARGET_CLASS)
}


@Lazy & @DependsOn

@Lazy
@Service
@DependsOn({"orderService", "currencyService"})
}


Factory method component

@Component
public class CurrencyRepositoryFactory {

@Bean
@Lazy
@Scope("prototype")
@Qualifier("public")
public CurrencyRepository getCurrencyRepository() {
return new CurrencyMapRepository();
}
}


JSR 330
@Named
@Singleton

@Inject

@Inject
public AccountServiceImpl(@Named("default") AccountRepository r) {}

@Inject
public void setAccountRepository(AccountRepository repository) {}

}


@Autowired vs @Inject
Spring JSR-330 JSR-330 restrictions
@Autowired @Inject has no ‘required’ attribute
@Component @Named
@Scope @Scope only for meta-annotations and injection points
@Scope @Singleton default scope is like ‘prototype’
@Qualifier @Named
@Value X
@Required X
@Lazy X


Java-based configuration
Configuration
Basic annotations


Instantiatiating for standalone
 simple
new AnnotationConfigApplicationContext(ExchangerConfig.class);

 programmaticaly
context = new AnnotationConfigApplicationContext();
context.register(ExchangerConfig.class);
context.refresh();

 scanning
context = new AnnotationConfigApplicationContext();
context.scan("org.exchanger.config");
context.refresh();


Instantiating bean

@Configuration
public class ExchangerRepositoryConfg {

@Bean(name = "accountRepository", initMethod = "init")
public AccountRepository accountRepository() {
return new AccountMapRepository();
}

@Bean
public AuditRepository auditRepository() {
return new AuditMapRepository();
}
}


@Import

@Configuration
@Import({RepositoryConfig.class, ServiceConfig.class})
public class ExchangerConfig {
}

@Configuration
public class RepositoryConfg {}

@Configuration
public class ServiceConfig {}


@ImportResources
@Configuration
@ImportResource("classpath:jdbc.properties")
public class ExchangerConfig {

@Value("jdbc.url")
private String jdbcUrl;

@Bean
public DataSourse dataSource() {
return new SimpleDataSource(jdbcUrl);
}
}


Dependency injection
@Configuration
public class ExchangerServiceConfig {

@Autowired
private CurrencyRepository currencyRepository;

public @Bean CurrencyService currencyService() {
return new CurrencyServiceImpl(currencyRepository);
}

@Bean(name = {"orderBuilder", "builder"})
public OrderBuilder orderBuilder() {
return new OrderBuilder(currencyService(), accountService());
}
}


Summary
Benefits of IoC
Context lifecycle
Mix and match


Benefits of IoC
 minimizes the amount of code
 make application more testable
 promote programming to interfaces
 loose coupling with minimal effort
 support eager instantiation and lazy loading
 provide control over object lifecycle


Context lifecycle


Approach to configuration
 XML
 infrastructure beans
 annotations
 working beans
 java
 an alternative to the FactoryBean


You can mix and match
 dependency injection
 constructor-based and setter-based
 you can mix and match

 configuration metadata
 XML, annotations, Java

 annotations
 own, JSR-250, JSR-330


Links
 site
http://www.springsource.org/
 reference
http://static.springsource.org/spring/docs/3.0.x/spring-
framework-reference/html/
 blog
http://blog.springsource.com/category/spring/
 forum
http://forum.springsource.org/forumdisplay.php?f=26


Books


Questions


The end

http://www.linkedin.com/in/noskovd

http://www.slideshare.net/analizator/presentations

Spring Framework - Core

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