Apring中AOP使用

在XML中配置切面

參見下圖

一、聲明前置和後置通知

其中展示了兩種聲明方法

可以直接聲明<aop:before pointcut="execution(* SpringStudy.Model.Counter.perform(..))"
method="turnOffCellPhones" />

也可以先聲明切點<aop:pointcut id="perform"
expression="execution(* SpringStudy.Model.Counter.perform(..))" />

然後用pointcut-ref指向該切點

<aop:config>
		<aop:aspect id="aspect" ref="audience">
			<aop:pointcut id="perform"
				expression="execution(* SpringStudy.Model.Counter.perform(..))" />
			<aop:before pointcut-ref="perform" method="takeSeats" />
			<aop:before pointcut="execution(* 
		SpringStudy.Model.Counter.perform(..))"
				method="takeSeats" />
			<aop:before pointcut="execution(* SpringStudy.Model.Counter.perform(..))"
				method="turnOffCellPhones" />
			<aop:after-returning
				pointcut="execution(* SpringStudy.Model.Counter.perform(..))"
				method="applaud" />
		</aop:aspect>
	</aop:config>

Counter

package SpringStudy.Model;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;



@Component
public class Counter {	
	public void perform() {
		System.out.println("performing");
	}
}

Audience

package SpringStudy.Model.Aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.springframework.stereotype.Component;

@Component
public class Audience {
	public void takeSeats() {
		System.out.println("The audiene is taking their seats.");
	}

	public void turnOffCellPhones() {
		System.out.println("The audiene is turning off their cellphones.");
	}

	public void applaud() {
		System.out.println("CLAP");
	}

	public void demandRefund() {
		System.out.println("Boo! we want our money back!");
	}
}

測試類

public class SpringTest {
	public static void main(String[] args) {
	ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 讀取bean.xml中的內容
	Counter c = ctx.getBean("counter", Counter.class);// 創建bean的引用對象
        c.perform();
	}
}

二、聲明環繞通知

<aop:config>
		<aop:aspect id="aspect" ref="audienceNew">
			<aop:pointcut id="perform"
				expression="execution(* SpringStudy.Model.Counter.perform(..))" />
			<aop:around pointcut-ref="perform" method="watchPerformance" />
		</aop:aspect>
</aop:config>

AudienceNew類，其他類同上

package SpringStudy.Model.Aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.springframework.stereotype.Component;

@Component
public class AudienceNew {

	public void watchPerformance(ProceedingJoinPoint joinpoint) {
		try {
			System.out.println("The audiene is taking their seats.");
			System.out.println("The audiene is turning off their cellphones.");
			long start = System.currentTimeMillis();
			joinpoint.proceed();
			long end = System.currentTimeMillis();
			System.out.println("CLAP");
		} catch (Throwable t) {
			System.out.println("Boo! we want our money back!");
		}

	}
}

註解切面

@Aspect標註一個類，表明這個類是一個切面

@Pointcut註解用於定義一個可以在@AspectJ切面內可以重用的切點，註解值是一個AspectJ表達式

@Before前置通知

@AfterReturing後置通知

@AfterThrowing拋異常時調用

@Around環繞通知

package SpringStudy.Model.Aop;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;

@Component
@Aspect
public class NewAudience {
	@Pointcut("execution(* SpringStudy.Model.Counter.perform(..))")
	public void performance() {

	}

	@Before("performance()")
	public void takeSeats() {
		System.out.println("The new  audiene is taking their seats.");
	}

	@Before("performance()")
	public void turnOffCellPhones() {
		System.out.println("The new audiene is turning off their cellphones.");
	}

	@AfterReturning("performance()")
	public void applaud() {
		System.out.println("new CLAP");
	}

	@AfterThrowing("performance()")
	public void demandRefund() {
		System.out.println("new Boo! we want our money back!");
	}
	@Around("performance()")
	public void watchPerformance(ProceedingJoinPoint joinpoint) {
		try {
			System.out.println("around The audiene is taking their seats.");
			System.out.println("around The audiene is turning off their cellphones.");
			long start = System.currentTimeMillis();
			joinpoint.proceed();
			long end = System.currentTimeMillis();
			System.out.println("around CLAP");
		} catch (Throwable t) {
			System.out.println("around Boo! we want our money back!");
		}

	}
}