Spring实战读书笔记 第四章 面向切面的Spring

1，AOP术语

    -1，通知（advice）：通知定义了切面是什么时候以及何时用的。除了描述切面的工作，通知还决定了合适解决。Spring切面可以用5中类型的通知。

    Before：在方法调用之前使用。

    After：在方法完成之后调用通知，无论方法是否执行成功。

    After-returning：在方法执行成功后调用。

    After-throwing：在方法抛出异常后调用。

    Around：通知包裹了被通知的方法，在被通知的方法调用之前和调用之后执行自定义行为。

    -2，切点（pointcut）：一个或多个连接点。

    -3，连接点（join point）：应用在执行过程中能够插入切面的点。

    -4，切面（Aspect）：切面是通知和切点的结合，通知和切点共同定义了关于切面的全部内容。

    -5，引入（Introduction）：引入允许我们向现有的类添加新的方法或属性。

2，Spring借助AspectJ的切点表达式语言来定义Spring切面

    -1，arg() ：限制连接点匹配参数为制定类型的执行方法。

    -2，@args() ：限制连接点匹配参数由制定注解标注的执行方法。

    -3，execution()：用于匹配是连接点的执行方法。

    -4，this()：限制连接点匹配AOP代理的Bean引用为制定类型的类。

    -5，target()：限制连接点匹配目标对象为制定类型的类。

    -6，@target()：限制连接点匹配特定的执行对象，这些对象对应的类要具备制定注解。

    -7，within()：限制连接点匹配指定的类型。

    -8，@within()：限制连接点匹配制定注解的类型。

    -9，@annotation：限制匹配带有制定注解连接点。

3，编写切点：

<aop:config>
		<aop:aspect ref="audience">
			<aop:before
				pointcut="execution(* chp02.springdol.Perform.perform(..))"
				method="takeSeat" />
			<aop:before
				pointcut="execution(* chp02.springdol.Perform.perform(..))"
				method="turnOffCellPhone" />
			<aop:after-returning
				pointcut="execution(* chp02.springdol.Perform.perform(..))"
				method="applaud" />
			<aop:after-throwing
				pointcut="execution(* chp02.springdol.Perform.perform(..))"
				method="demandRefund" />
		</aop:aspect>
	</aop:config>

package chp04.aop;
 
/**
 *  类描述：观众类，测试AOP
 * 
 *  @author:  Jing
 *  History:  Jan 7, 2015 3:33:35 PM   Jing   Created.
 *           
 */
public class Audience {
	
	public void takeSeat(){
		
		System.out.println("The audience is taking their seats.");
	}
	
	public void turnOffCellPhone(){
		
		System.out.println("The audience is turning off their cellphone!");
	}
	
	public void applaud(){
		
		System.out.println("CLAP CLAP CLAP CLAP CLAP ");
	}
	
	public void demandRefund(){
		
		System.out.println("Boo! we want our money back!");
	}
	
}

package chp04.aop;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
import chp02.springdol.Perform;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 8, 2015 4:52:20 PM   Jing   Created.
 *           
 */
public class Main {
 
	public static void main(String[] args) {
		
		ApplicationContext ctx = new ClassPathXmlApplicationContext("chp04/aop/spring.xml");
 
		Perform perform = (Perform) ctx.getBean("juggler");
		perform.perform();
	}
}

输出结果
The audience is taking their seats.
The audience is turning off their cellphone!
Juggler perform(),beanBags : 3
CLAP CLAP CLAP CLAP CLAP 

因为以上涉及到的切点都相同，我们可以将切点配置抽取，如下：

	<aop:config>
 
		<aop:aspect ref="audience">
			<aop:pointcut id="perform"
				expression="execution(* chp02.springdol.Perform.perform(..))" />
			<aop:before pointcut-ref="perform" method="takeSeat" />
			<aop:before pointcut-ref="perform"
				method="turnOffCellPhone" />
			<aop:after-returning pointcut-ref="perform"
				method="applaud" />
			<aop:after-throwing pointcut-ref="perform"
				method="demandRefund" />
		</aop:aspect>
	</aop:config>

声明环绕通知

    环绕通知java处理代码：

/**
	 * 
	 * 方法说明：环绕通知
	 * 
	 * Author： Jing Create Date： Jan 9, 2015 10:44:37 AM
	 */
	public void watchPerformance(ProceedingJoinPoint joinPoint) {
		try {
 
			System.out.println("The audience is taking their seats.");
			System.out.println("The audience is turning off their cellphone!");
			long start = System.currentTimeMillis();
 
			joinPoint.proceed();
			
			long end = System.currentTimeMillis();
			
			System.out.println("CLAP!CLAP!CLAP!CLAP!");
			System.out.println("The perform took " + ( end - start) + " s");
		} catch (Throwable e) {
 
			System.out.println("Exception,  we want our money back! ");
		}
 
	}

环绕通知XML配置：

 
	<aop:config>
		<aop:aspect ref="audience">
			<aop:pointcut id="perform2"
				expression="execution(* chp02.springdol.Perform.perform(..))" />
			<aop:around pointcut-ref="perform2"
				method="watchPerformance" />
		</aop:aspect>
	</aop:config>

为通知传递参数：

package chp04.aop;
 
/**
 *  类描述：测试通知参数
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 11:00:32 AM   Jing   Created.
 *           
 */
public interface MindReader {
	
	void interceptThoughts(String thoughts);
	
	String getThoughts();
}

package chp04.aop;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 2:13:29 PM   Jing   Created.
 *           
 */
public class Magician implements MindReader{
 
	private String thoughts;
 
	public String getThoughts() {
		
		return thoughts;
	}
 
	public void setThoughts(String throughts) {
		this.thoughts = throughts;
	}
 
	@Override
	public void interceptThoughts(String throughts) {
 
		System.out.println("intercept  Thoughts");
		this.thoughts = throughts;
	}
}

package chp04.aop;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 2:26:51 PM   Jing   Created.
 *           
 */
public interface Thinker {
 
	void thinkOfSomething(String thoughts);
	
	public String getThoughts();
}

package chp04.aop;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 2:27:48 PM   Jing   Created.
 *           
 */
public class Volunteer implements Thinker {
	
	private String thoughts;
 
	@Override
	public void thinkOfSomething(String thoughts) {
		
		this.thoughts = thoughts;
	}
 
	public String getThoughts() {
		return thoughts;
	}
 
}

		<bean id="volunteer" class="chp04.aop.Volunteer" />
		<bean id="magician" class="chp04.aop.Magician" />
 
		<aop:config>
			<aop:aspect ref="magician">
				<aop:pointcut id="thinking" expression="execution(* chp04.aop.Thinker.thinkOfSomething(String)) and args(thoughts)"/>
				<aop:before pointcut-ref="thinking" method="interceptThoughts" arg-names="thoughts"/>
			</aop:aspect>
			
		</aop:config>

package chp04.aop;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 8, 2015 4:52:20 PM   Jing   Created.
 */
public class Main {
 
	public static void main(String[] args) {
		
		ApplicationContext ctx = new ClassPathXmlApplicationContext("chp04/aop/spring.xml");
 
//		Volunteer volunteer = (Volunteer) ctx.getBean("volunteer");
//		volunteer.thinkOfSomething("Thinking the world!");
		
		Thinker volunteer =  (Thinker) ctx.getBean("volunteer");//因为AOP配置，此处必须转换为接口
		volunteer.thinkOfSomething("Thinking the world!");
		System.out.println(volunteer.getThoughts());
	}
}

4，通过切面引入新功能。

package chp04.aop;
 
/**
 *  类描述：其他功能接口
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 3:15:40 PM   Jing   Created.
 *           
 */
public interface Contestant {
 
	void receiveAward();
}

package chp04.aop;
 
/**
 *  类描述：接口实现
 * 
 *  @author:  Jing
 *  History:  Jan 9, 2015 3:25:47 PM   Jing   Created.
 *           
 */
public class GraciousContestant implements Contestant{
 
	@Override
	public void receiveAward() {
		
		System.out.println("Auto Add method");
	}
 
}

	<bean id="graciousContestant" class="chp04.aop.GraciousContestant" />
	<aop:config>
		<aop:aspect>
			<aop:declare-parents types-matching="chp04.aop.Thinker+"
				implement-interface="chp04.aop.Contestant"
				delegate-ref="graciousContestant" />
			<!--default-impl="chp04.aop.GraciousContestant"/> 此处同delegate-ref 目的一致，声明对应接口的默认实现 -->
		</aop:aspect>
	</aop:config>

package chp04.aop;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
/**
 *  类描述：
 * 
 *  @author:  Jing
 *  History:  Jan 8, 2015 4:52:20 PM   Jing   Created.
 */
public class Main {
 
	public static void main(String[] args) {
		
		ApplicationContext ctx = new ClassPathXmlApplicationContext("chp04/aop/spring.xml");
 
 
		Contestant volunteer =  (Contestant) ctx.getBean("volunteer");
		
		volunteer.receiveAward();
	}
}

5，基于注解的配置

 
package chp04.aop;
 
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
 
/**
 * 类描述：观众类，测试AOP
 * 
 * @author: Jing History: Jan 7, 2015 3:33:35 PM Jing Created.
 * 
 */
@Aspect
public class Audience {
	
	@Pointcut("execution(* chp02.springdol.Perform.perform(..))")
	/**
	 * 定义切点
	 */
	public void perform(){
		
	}
	@Before("perform()")
	public void takeSeat() {
 
		System.out.println("The audience is taking their seats.");
	}
	@Before("perform()")
	public void turnOffCellPhone() {
 
		System.out.println("The audience is turning off their cellphone!");
	}
	@AfterReturning("perform()")
	public void applaud() {
 
		System.out.println("CLAP CLAP CLAP CLAP CLAP ");
	}
	
	@AfterThrowing("perform()")
	public void demandRefund() {
 
		System.out.println("Boo! we want our money back!");
	}
 
	/**
	 * 
	 * 方法说明：环绕通知
	 * 
	 * Author： Jing Create Date： Jan 9, 2015 10:44:37 AM
	 */
	public void watchPerformance(ProceedingJoinPoint joinPoint) {
		try {
 
			System.out.println("The audience is taking their seats.");
			System.out.println("The audience is turning off their cellphone!");
			long start = System.currentTimeMillis();
 
			joinPoint.proceed();
			
			long end = System.currentTimeMillis();
			
			System.out.println("CLAP!CLAP!CLAP!CLAP!");
			System.out.println("The perform took " + ( end - start) + " s");
		} catch (Throwable e) {
 
			System.out.println("Exception,  we want our money back! ");
		}
 
	}
 
}

配置文件启用注解API

<aop:aspectj-autoproxy />

环绕通知：

 
	/**
	 * 
	 * 方法说明：环绕通知
	 * 
	 * Author： Jing Create Date： Jan 9, 2015 10:44:37 AM
	 */
	@Around("perform()")
	public void watchPerformance(ProceedingJoinPoint joinPoint) {
		try {
 
			System.out.println("The audience is taking their seats.");
			System.out.println("The audience is turning off their cellphone!");
			long start = System.currentTimeMillis();
 
			joinPoint.proceed();
			
			long end = System.currentTimeMillis();
			
			System.out.println("CLAP!CLAP!CLAP!CLAP!");
			System.out.println("The perform took " + ( end - start) + " s");
		} catch (Throwable e) {
 
			System.out.println("Exception,  we want our money back! ");
		}
 
	}