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Spring & AOP

Margus JägerLauri Tulmin

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Sissejuhatus

• 3. peatükk raamatus Spring in Action• 4. peatükk raamatus Professional Java

Development with the Spring Framework• Spring• Spring AOP• Võrdlus AspectJ’ga

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Spring

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Spring

• Kergekaaluline (Lightweight)• Kontrolli ümberpööramine (Inversion of

control)• Aspektidele orienteeritud (Aspect-oriented)• Konteiner• Raamistik (Framework)

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Hello World näide 1public interface IHello {

public void sayHello();}

public class Hello implements IHello {private IGreeting greeting;

public void setGreeting(IGreeting greeting) {this.greeting = greeting;

}

public void sayHello() {System.out.println(greeting.getGreeting());

}}

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Hello World näide 2public interface IGreeting {

public String getGreeting(); }

public class Greeting implements IGreeting {private String greeting;

public String getGreeting() {return greeting;

}

public void setGreeting(String greeting) {this.greeting = greeting;

}}

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Hello World näide 3<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"><beans> <bean id="hello" class="Hello"> <property name="greeting"> <ref local="greeting" /> </property> </bean> <bean id="greeting" class="Greeting"> <property name="greeting"> <value>hello world</value> </property> </bean></beans>

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Hello World näide 4public class Main {

public static void main(String[] args) {Resource res = new FileSystemResource("beans.xml");XmlBeanFactory factory = new XmlBeanFactory(res);IHello hello = (IHello)factory.getBean("hello");

hello.sayHello();}

}

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Spring & AOP

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Spring AOP

• Aspektid kirjutatakse javas• Ühendpunktideks on meetodid• Aspektide rakendamine programselt või

deklaratiivselt Springi konfiguratsioonifailis

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AOP Alliance

• http://aopalliance.sourceforge.net/

• Kõik Springis kasutatavad juhised realiseerivad AOP Alliance’i spetsifitseeritud või neist päritud liideseid

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Juhised

• Before• After returning• Around• Throws• Introduction

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Around juhispublic interface MethodInterceptor extends Interceptor {

Object invoke(MethodInvocation invocation) throws Throwable;

}

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public class PerformanceInterceptor implements MethodInterceptor { 

public Object invoke(MethodInvocation method) throws Throwable {

long start = System.currentTimeMillis();try {

Object result = method.proceed();return result;

}finally {

long end = System.currentTimeMillis();long timeMs = end - start;System.out.println("Method: " + method.toString() +

" took: " + timeMs +"ms.");}

}}

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Before juhispublic interface MethodBeforeAdvice extends BeforeAdvice { void before(Method m, Object[] args, Object target) throws

Throwable;}

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public class CountingBeforeAdvice implements MethodBeforeAdvice {

private int count;

public void before(Method m, Object[] args, Object target) { ++count; } public int getCount() { return count; }}

Before juhise näide

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After Returning juhispublic interface AfterReturningAdvice extends Advice { void afterReturning(Object returnValue, Method m, Object[] args, Object

target) throws Throwable;}

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public class CountingAfterReturningAdvice implements AfterReturningAdvice {

private int count;

public void afterReturning(Object returnValue, Method m, Object[] args, Object target) { ++count; } public int getCount() { return count; }}

After Returning juhise näide

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Throws juhis

org.springframework.aop.ThrowsAdvice

afterThrowing([Method, args, target,] Throwable)

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public static class ServletThrowsAdviceWithArguments implements ThrowsAdvice { public void afterThrowing

(Method m, Object[] args, Object target,ServletException ex) {

// Do something with all arguments } public void afterThrowing(RemoteException ex) throws Throwable { // Do something with remote exception }}

Throws juhise näide

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Lõikepunktid

• Ühendpunktid (JoinPoints) on Springis alati meetodid

• Lõikepunktid (Pointcuts) defineerivad, millistele meetoditele juhiseid rakendatakse

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Lõikepunktid Springis

• org.springframework.aop.support.NameMatchMethodPointcut

• org.springframework.aop.support.DynamicMethodMatcherPointcut

• org.springframework.aop.StaticMethodMatcherPointcut

• org.springframework.aop.support.JdkRegexpMethodPointcut

• org.springframework.aop.support.Perl5RegexpMethodPointcut

• org.springframework.aop.support.ControlFlowPointcut

• org.springframework.aop.support.ComposablePointcut

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NameMatchMethodPointcut klass

• NameMatchMethodPointcut addMethodName(String methodName) 

• void setMappedName(String methodName) • void setMappedNames(String methodName)

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NameMatchMethodPointcuti kasutamise näide Javas

Pointcut pc = new NameMatchMethodPointcut().addMethodName("setAge").addMethodName("setName");

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Regulaaravaldistega lõikepunktid<bean id="settersAndAbsquatulatePointcut" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="patterns"> <list> <value>.*get.*</value> <value>.*absquatulate</value> </list> </property></bean>

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Staatiline (ei sõltu argumentidest)public class MyBeanPointcut extends StaticMethodMatcherPointcut {

public boolean matches(Method theMethod, Class theClass) {

return (MyBean.class.isAssignableFrom(theClass) && theMethod.equals(...));

}

}

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Dünaamiline (arvestab argumente)public class MyBeanPointcut extends DynamicMethodMatcherPointcut {

public boolean matches(Method theMethod, Class theClass, Object[] arguments) {

boolean matches = false;

if (MyBean.class.isAssignableFrom(theClass) && theMethod.equals(...)) {

if (arguments[0].equals("Joe Smith")) { matches = true; }

}return matches;

}}

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ControlFlowPointcut

<bean id="servletPointcut"class="org.springframework.aop.support.ControlFlowPointcut">

<constructor-arg><value>javax.servlet.http.HttpServlet</value>

</constructor-arg>

</bean>

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Tehted lõikepunktidega

public static Pointcut union(Pointcut a, Pointcut b)

  kas a või b  

public static Pointcut intersection(Pointcut a, Pointcut b)

nii a kui b

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Juhtpunktid - Advisors

• (pakkuge hea tõlge)• Ühendavad Springis lõikepunktid ja

juhised aspektiks• Võivad sisaldada lõikepunktide

defineerimiseks vajalikke meetodeid (pole vaja lõikepunktide jaoks eraldi klasse defineerida)

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DefaultPointcutAdvisorpublic class DefaultPointcutAdvisor {

private Pointcut pointcut;

private Advice advice;

public Pointcut getPointcut() { return pointcut; }

public Advice getAdvice() { return advice; }

public void setPointcut(Pointcut pc) { pointcut = pc; }

public void setAdvice(Advice a) { advice = a; }

}

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DefaultPointcutAdvisor (2)

<bean name ="myAdvisor“ class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut">

<ref local="myPointcut"/> </property> <property name="advice">

<ref local="myAdvice"/> </property></bean>

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NameMatchMethodPointcutAdvisor

<bean name="advisor1" class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor"> <property name="advice" ref="beforeAdviceA"/> <property name="mappedName" value=“myMethod"/></bean>

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RegexpMethodPointcutAdvisor<bean id=“advisor2" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">        <property name="advice">

<ref local="myAdvice"/> </property>

<property name="patterns"> <list> <value>.*set.*</value> <value>.*getName</value> </list> </property></bean>

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AOP realiseerimine

• Kompileerimisel (AspectJ)• Klassi laadimisel• Programmi käimisel (Spring)

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Staatiline vs dünaamiline• Statiline AOP- Kompileerimisel põimitakse aspektid java

klassidesse- AspectJ• Dünaamiline AOP- Aspektid põimitakse programmi töö ajal- Klasse pole vaja uuesti kompileerida- Aspektide jaoks vahendaja (proxy)- Spring

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Vahendajad (Proxy)

• JDK Dynamic Proxy- Rakendatav objektidele, mille klassid

realiseerivad liideseid• CGLIB Proxy- Lennult genereeritakse antud klassi

laiendav klass

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ProxyFactoryBean

• Loob vahendaja-objeti, millele rakendatakse aspekte

• Saab siduda objektiga nii juhiseid (advice) kui juhtpunkte (advisor)

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<bean id="myDependency1"class="org.springframework.aop.framework.ProxyFactoryBean">

<property name="target"><ref local="myDependencyTarget"/>

</property><property name="interceptorNames">

<list><value>myAdvice</value><value>myAdvisor</value>

</list></property>

</bean>

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Automaatsed vahendajad

• BeanNameAutoProxyCreator• DefaultAdvisorAutoProxyCreator

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<bean id="proxyCreator"class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">

<property name="beanNames"><list>

<value>foo*</value><value>barBean</value>

</list></property>

<property name="interceptorNames"><list>

<value>advice</value></list>

</property></bean>

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DefaultAdvisorAutoProxyCreator

• Juhtpunkte rakendatakse kõikidele objektidele

<bean id="aapc" class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"/ >

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Spring AOP vs AspectJ

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Spring ja AspectJ võrdlus

Spring AOP• Lihtne seadistada• Käimise ajal• AOP Alliance’i

liidesed• Vähem võimalusi

AspectJ• Väheke keerulisem• Kompileerimisel• Eraldi

programmeerimiskeel• Rohkem võimalusi

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Süntaks- Spring AOP (AOP Alliance)public class SimpleMethodInterceptor implements MethodInterceptor {

public Object invoke(MethodInvocation invocation)throws Throwable {...return invocation.proceed();

}}- AspectJpublic aspect SimpleServiceAroundAspect {

pointcut serviceExecution():execution(public * ee.bus.*Service.*(..));

Object around(): serviceExecution() {...return proceed();

}}

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Spring AOP piirangud

• Ühenduspunktideks ainult meetodid• Ilma CgLibita aspektid ainult liideste

meetoditel• private, final, static meetoditele ei saa

aspekte panna• Aspektid rakendatakse ainult konteineri

poolt loodud objektidele

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Valmis aspektid

• Transaktsioonid• Puulimine• ACEGI security

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Jõudlus

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Spring AOP ja AspectJ jõudlus

autor: Rein Raudjärv

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Invocation Time [ms]

Number of Aspects

1 Million Method Invocations (Adding Numbers)

AspectJ (Before/After) AspcetJ (Around) Spring AOP

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Küsimused