spring（四）AOP相關概念

名詞解釋

AOP定義：面向切面編程

Joinpoint：連接點，即目標對象中，所有可以增強的方法

Pointcut：切入點，即目標對象中，已經增強的方法

Advice：通知，即需要增強的代碼

Target：目標對象，即被代理的對象

Weaving：織入，將通知應用到切入點的過程

Proxy：代理，將通知織入到目標對象之後，形成代理對象

aspect：切面，切入點+通知

AOP實現原理：

1.動態代理：被代理對象必須要實現接口

2.CGLib代理：可以對任何類生成代理，代理的原理是對目標對象進行繼承代理 

相關代碼：

用戶接口：

public interface UserService {

	void add();
	
	void delete();
	
	void update();
	
	void search();
	
}

用戶接口實現類：

public class UserServiceImpl implements UserService {

	@Override
	public void add() {
		System.out.println("add");
	}

	@Override
	public void delete() {
		System.out.println("delete");
	}

	@Override
	public void update() {
		System.out.println("update");
	}

	@Override
	public void search() {
		System.out.println("search");
	}

}

通知類：

public class UserAdvice {

	//前置通知：目標方法運行前調用
	public void before(){
		System.out.println("before");
	}
	
	//後置通知：方法出現異常不會調用此通知
	public void afterReturning(){
		System.out.println("afterReturning");
	}
	
	//環繞通知：目標方法執行前後都被調用
	public Object around(ProceedingJoinPoint joinPoint) throws Throwable{
		System.out.println("around before");
		Object proceed = joinPoint.proceed();
		System.out.println("around after");
		return proceed;
	}
	
	public void afterException(){
		System.out.println("afterException");
	}
	
	//後置通知：方法出現異常也調用此通知
	public void after(){
		System.out.println("after");
	}
	
}

配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd ">

<!-- 導入aop約束 -->
<!-- 1.配置目標對象 -->
	<bean name="userService" class="com.milan.spring.service.impl.UserServiceImpl"></bean>
<!-- 2.配置通知對象 -->
	<bean name="myAdvice" class="com.milan.advice.UserAdvice"></bean>
<!-- 3.配置將通知織入目標對象 -->
	<aop:config>
		<!-- 配置切入點
			public void com.milan.spring.service.impl.UserServiceImpl.add()
			void com.milan.spring.service.impl.UserServiceImpl.add()
			* com.milan.spring.service.impl.UserServiceImpl.add()
			* com.milan.spring.service.impl.UserServiceImpl.*(..)
			* com.milan.spring.service.impl.*ServiceImpl.*(..)
		 -->
		<aop:pointcut expression="execution(public void com.milan.spring.service.impl.UserServiceImpl.add())" id="user_add"/>
		<aop:aspect ref="myAdvice">
			<aop:before method="before" pointcut-ref="user_add" />
			<aop:after-returning method="afterReturning" pointcut-ref="user_add"/>
			<aop:around method="around" pointcut-ref="user_add"/>
			<aop:after-throwing method="afterException" pointcut-ref="user_add"/>
			<aop:after method="after" pointcut-ref="user_add"/>
		</aop:aspect>
	</aop:config>

</beans>

測試：

@RunWith(SpringJUnit4ClassRunner.class)//創建容器
@ContextConfiguration("classpath:applicationContext-advice.xml")//指定配置文件位置
public class AdviceTest {
	
	@Resource(name="userService")
	private UserService service;
	
	@Test
	public void Test1(){
		service.add();
	}
	
}

輸出如下：

before
around before
add
after
around after
afterReturning

註釋配置：

配置切面：

@Aspect
//表示該類爲一個通知類
public class UserAdviceByAnnotation {

	@Pointcut("execution(* com.milan.spring.service.impl.*ServiceImpl.*(..))")
	public void advice(){}
	
	
	//前置通知：目標方法運行前調用
	@Before("UserAdviceByAnnotation.advice()")
	public void before(){
		System.out.println("before");
	}
	
	//後置通知：方法出現異常不會調用此通知
	@AfterReturning("execution(* com.milan.spring.service.impl.*ServiceImpl.*(..))")
	public void afterReturning(){
		System.out.println("afterReturning");
	}
	
	//環繞通知：目標方法執行前後都被調用
	@Around("execution(* com.milan.spring.service.impl.*ServiceImpl.*(..))")
	public Object around(ProceedingJoinPoint joinPoint) throws Throwable{
		System.out.println("around before");
		Object proceed = joinPoint.proceed();
		System.out.println("around after");
		return proceed;
	}
	
	@AfterReturning("execution(* com.milan.spring.service.impl.*ServiceImpl.*(..))")
	public void afterException(){
		System.out.println("afterException");
	}
	
	//後置通知：方法出現異常也調用此通知
	@After("execution(* com.milan.spring.service.impl.*ServiceImpl.*(..))")
	public void after(){
		System.out.println("after");
	}
	
}

配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd ">

<!-- 導入aop約束 -->
<!-- 1.配置目標對象 -->
	<bean name="userService" class="com.milan.spring.service.impl.UserServiceImpl"></bean>
<!-- 2.配置通知對象 -->
	<bean name="myAdvice" class="com.milan.advice.UserAdviceByAnnotation"></bean>
<!-- 3.配置將通知織入目標對象 -->
	<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

</beans>	

測試：

@RunWith(SpringJUnit4ClassRunner.class)//創建容器
@ContextConfiguration("classpath:applicationContext-advice-annotation.xml")//指定配置文件位置
public class AdviceByAnnotationTest {
	
	@Resource(name="userService")
	private UserService service;
	
	@Test
	public void Test1(){
		service.add();
	}
	
}

輸出如下：

around before
before
add
around after
after
afterException
afterReturning