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Spring面向切面 --- AspectJ --- 简单使用

2024-07-20 11:55:15 220人阅读

Spring面向切面 --- AspectJ --- 简单使用

昨天回复说说的时候突然写下了下面的一段话：分享一下：

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其实经过的记忆是可以进行道德化的篡改的，
就像夏目漱石的《我是猫》；
但是不管怎么改，真正的事实是由每一个人的碎片拼起来的；
经济学里计算成本的是在计算将来的成本而不是过去的成本，
就像动漫《未来日记》一样；
过去发生的事情总是在影响着将来，
但是过去发生的事情却不能充当将来下一个操作符的影响要素。
********************************************-->

面向切面编程用到了动态代理，感兴趣的读者可以参考我的日志：

http://www.cnblogs.com/kodoyang/p/DesignPattern_DynamicProxy.html

1.AspectJ - AOP
面向切面编程是面向对象的一个补充

在保存用户前添加一个日志，再加上时刻的记录。总之，就是方法前后加一点业务逻辑

新建资源库：Preference>Java>BuildPath>UserLibraries，AddLibrary>UserLibrary

/Spring_AOP/src/yuki/spring/aop/imitate/UserService.java

package yuki.spring.aop.imitate;public interface UserService {    void save();}

/Spring_AOP/src/yuki/spring/aop/imitate/UserServiceImpl.java

package yuki.spring.aop.imitate;public class UserServiceImpl implements UserService{    public void save(){        System.out.println("user saved...");    }}

/Spring_AOP/src/yuki/spring/aop/imitate/Intercepter.java

package yuki.spring.aop.imitate;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;public abstract class Intercepter implements InvocationHandler {    private Object target;    public void setTarget(Object target) {        this.target = target;    }        protected abstract void beforeMethod();    protected abstract void afterMethod();        @Override    public Object invoke(Object proxy, Method m, Object[] args)            throws Throwable {        beforeMethod();        m.invoke(target, args);        afterMethod();        return null;    }}

/Spring_AOP/src/yuki/spring/aop/imitate/LogIntercepter.java

package yuki.spring.aop.imitate;public class LogIntercepter extends Intercepter {    @Override    public void beforeMethod() {        System.out.println("log start...");    }    @Override    protected void afterMethod() {        System.out.println("log end...");    }}

/Spring_AOP/src/yuki/spring/aop/imitate/TimeIntercepter.java

package yuki.spring.aop.imitate;public class TimeIntercepter extends Intercepter {    @Override    protected void beforeMethod() {        System.out.println("start:" + System.currentTimeMillis());    }    @Override    protected void afterMethod() {        System.out.println("end:" + System.currentTimeMillis());    }}

/Spring_AOP/src/yuki/spring/aop/imitate/ProxyTest.java

package yuki.spring.aop.imitate;import java.lang.reflect.Proxy;public class ProxyTest {    public static void main(String[] args) {        UserService service = new UserServiceImpl();                Intercepter[] intercepters = {new LogIntercepter(), new TimeIntercepter()};        for(Intercepter intercepter : intercepters){            intercepter.setTarget(service);            service = (UserService) Proxy.newProxyInstance(                    service.getClass().getClassLoader(),                     service.getClass().getInterfaces(), intercepter);        }                service.save();            }}

上面的程序中，两个类继承了实现InvocationHandler接口的抽象类，

也可以说是间接地实现了InvocationHandler接口；

声明为UserService接口类型的service，

在循环中每一次接收Proxy.newProxyInstance方法的计算结果后就会改变它指向的对象。

运行结果如下：

start:1409496143248log start...user saved...log end...end:1409496143250

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

注解的方式实现AOP使用的是aspectj，aspectj是专门用来产生动态代理的一个框架
可以使用aspectj注解的方式实现spring的AOP，把这个逻辑织入到原来的逻辑里面去

引入jar：aspectjrt.jar、aspectj-weaver.jar：http://www.java2s.com/Code/Jar/a/aspectj.htm

在类上添加注解 @Aspect和 @Component，在方法上添加注解 @Before
切入点语法 @Before("execution(public void yuki.spring.aop.annotation"
+ ".UserServiceImpl.save(yuki.spring.aop.annotation.User))")
引入jar：aopalliance-.jar：http://www.java2s.com/Code/Jar/a/Downloadaopalliancejar.htm
@Component要加在对应的实现类上，因为getBean后要获取这个对象

/Spring_AOP/src/yuki/spring/aop/annotation/User.java

package yuki.spring.aop.annotation;public class User {}

/Spring_AOP/src/yuki/spring/aop/annotation/UserService.java

package yuki.spring.aop.annotation;public interface UserService {    void save(User user);}

/Spring_AOP/src/yuki/spring/aop/annotation/UserServiceImpl.java

package yuki.spring.aop.annotation;import org.springframework.stereotype.Component;@Component("userService")public class UserServiceImpl implements UserService{    public void save(User user){        System.out.println("user saved...");    }}

/Spring_AOP/src/annotation.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:context="http://www.springframework.org/schema/context"     xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://www.springframework.org/schema/beans                         http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                         http://www.springframework.org/schema/aop                         http://www.springframework.org/schema/aop/spring-aop-4.0.xsd                         http://www.springframework.org/schema/context                         http://www.springframework.org/schema/context/spring-context-4.0.xsd ">        <context:annotation-config></context:annotation-config>    <context:component-scan base-package="yuki.spring.aop.annotation"></context:component-scan>        <aop:aspectj-autoproxy></aop:aspectj-autoproxy>    </beans>

/Spring_AOP/src/yuki/spring/aop/annotation/LogIntercepter.java

package yuki.spring.aop.annotation;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.springframework.stereotype.Component;@Aspect@Componentpublic class LogIntercepter {    @Before("execution(public void yuki.spring.aop.annotation"            + ".UserServiceImpl.save(yuki.spring.aop.annotation.User))")    public void beforeMethod() {        System.out.println("method start...");    }}

/Spring_AOP/src/yuki/spring/aop/annotation/TimeIntercepter.java

package yuki.spring.aop.annotation;import org.aspectj.lang.annotation.AfterReturning;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.springframework.stereotype.Component;@Aspect@Componentpublic class TimeIntercepter {    @Before("execution("            + "public * yuki.spring.aop.annotation..*.*(..)"            + ")")    public void beforeMethod() {        System.out.println("before:" + System.currentTimeMillis());    }    @AfterReturning("execution( public * yuki.spring.aop.annotation..*.*(..) )")    public void afterReturningMethod() {        System.out.println("afterReturning:" + System.currentTimeMillis());    }}

/Spring_AOP/src/yuki/spring/aop/annotation/PointcutIntercepter.java

package yuki.spring.aop.annotation;import org.aspectj.lang.annotation.AfterReturning;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.aspectj.lang.annotation.Pointcut;import org.springframework.stereotype.Component;@Aspect@Componentpublic class PointcutIntercepter {    @Pointcut("execution( public * yuki.spring.aop.annotation..*.*(..) )")    public void myMethod() {}        @Before("myMethod()")    public void beforeMethod() {        System.out.println("PointcutIntercepter::before");    }    @AfterReturning("myMethod()")    public void afterReturningMethod() {        System.out.println("PointcutIntercepter::afterReturning");    }}

/Spring_AOP/src/yuki/spring/aop/annotation/UserServiceTest.java

package yuki.spring.aop.annotation;import org.junit.Test;import org.springframework.context.support.ClassPathXmlApplicationContext;public class UserServiceTest {    @Test    public void testSave() {                @SuppressWarnings("resource")        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("annotation.xml");        UserService service = (UserService) context.getBean("userService");        service.save(new User());        context.destroy();    }}

运行结果如下：

八月 31, 2014 10:59:10 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 22:59:10 CST 2014]; root of context hierarchy八月 31, 2014 10:59:10 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [annotation.xml]method start...PointcutIntercepter::beforebefore:1409497152268user saved...afterReturning:1409497152268PointcutIntercepter::afterReturning八月 31, 2014 10:59:12 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 22:59:10 CST 2014]; root of context hierarchy

术语解释：
JoinPoint：连接点、切入点，在哪里把逻辑加进区
PointCut:JoinPoint的集合，可以一次性定义好多切入点
Aspect：切面，切面类加进去的逻辑可以认为是一个切面
Advice：在这个点上建议怎么办，比如 @Before
Target：被织入逻辑的被代理对象
Weave：织入

2.切面和通知
切入点：
// the execution of any public method:
execution(public * *(..))
// the execution of any method with a name beginning with "set":
execution(* set*(..))
// the execution of any method defined by the AccountService interface:
execution(* com.xyz.service.AccountService.*(..))
// the execution of any method defined in the service package:
execution(* com.xyz.service..(..))
// the execution of any method defined in the service package or a sub-package:
execution(* com.xyz.service..*.*(..))
spring也定义了自己的织入点语法，但是我们只要用AspectJ的语法就可以了

通知：
Before、AfterReturn、AfterThrowing、After(意思是finally)
Around：在ProceedingJoinPoint.proceed()前后加逻辑

如果织入点表达式相同，可以定义Pointcut
定义方法名接收织入点表达式的值，使用时 @AfterReturning("pointcut()")

/Spring_AOP/src/yuki/spring/aop/pointcut/User.java

package yuki.spring.aop.pointcut;public class User {}

/Spring_AOP/src/yuki/spring/aop/pointcut/UserService.java

package yuki.spring.aop.pointcut;public interface UserService {    void save(User user);}

/Spring_AOP/src/yuki/spring/aop/pointcut/UserServiceImpl.java

package yuki.spring.aop.pointcut;import org.springframework.stereotype.Component;@Component("userService")public class UserServiceImpl implements UserService{    public void save(User user){        System.out.println("user saved...");        //throw new RuntimeException("exception...");    }}

/Spring_AOP/src/yuki/spring/aop/pointcut/TransactionAspect.java

package yuki.spring.aop.pointcut;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;@Aspect@Componentpublic class TransactionAspect {    @Pointcut("execution( public * yuki.spring.aop.pointcut..*.*(..) )")    public void pointcut(){}        @Before("pointcut()")    public void before(){        System.out.println("before");    }    @AfterReturning("pointcut()")    public void afterReturning(){        System.out.println("afterReturning");    }    @AfterThrowing("pointcut()")    public void afterThrowing(){        System.out.println("afterThrowing");    }        @Around("pointcut()")    public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable{        System.out.println("method around start...");        pjp.proceed();        System.out.println("method around end...");    }    }

/Spring_AOP/src/pointcut.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:context="http://www.springframework.org/schema/context"     xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://www.springframework.org/schema/beans                         http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                         http://www.springframework.org/schema/aop                         http://www.springframework.org/schema/aop/spring-aop-4.0.xsd                         http://www.springframework.org/schema/context                         http://www.springframework.org/schema/context/spring-context-4.0.xsd ">        <context:annotation-config></context:annotation-config>    <context:component-scan base-package="yuki.spring.aop.pointcut"></context:component-scan>        <aop:aspectj-autoproxy></aop:aspectj-autoproxy>    </beans>

/Spring_AOP/src/yuki/spring/aop/pointcut/UserServiceTest.java

package yuki.spring.aop.pointcut;import org.junit.Test;import org.springframework.context.support.ClassPathXmlApplicationContext;public class UserServiceTest {    @Test    public void testSave() {                @SuppressWarnings("resource")        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("pointcut.xml");        UserService service = (UserService) context.getBean("userService");        service.save(new User());        context.destroy();    }}

运行结果如下：

八月 31, 2014 11:09:22 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:09:22 CST 2014]; root of context hierarchy八月 31, 2014 11:09:22 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [pointcut.xml]method around start...beforeuser saved...method around end...afterReturning八月 31, 2014 11:09:24 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:09:22 CST 2014]; root of context hierarchy

可以实现声明式的异常管理，
struts2已经实现了声明式的异常管理，这里略过通知执行的先后顺序

3.cglib
如果被代理的类实现了接口，就会使用JDK自带的Proxy和InvocationHandler来实现代理
当被代理的类没有实现接口，它会用cglib直接操作二进制码的形式来产生代理的代码
引入jar：cglib-2.2.jar：http://www.java2s.com/Code/Jar/c/Downloadcglib22jar.htm

/Spring_AOP/src/yuki/spring/aop/cglib/UserService.java

package yuki.spring.aop.cglib;import org.springframework.stereotype.Component;@Componentpublic class UserService {    public void save(){        System.out.println("user saved...");    }}

/Spring_AOP/src/yuki/spring/aop/cglib/CglibAspect.java

package yuki.spring.aop.cglib;import org.aspectj.lang.ProceedingJoinPoint;import org.aspectj.lang.annotation.Around;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Pointcut;import org.springframework.stereotype.Component;@Aspect@Componentpublic class CglibAspect {    @Pointcut("execution( public * yuki.spring.aop.cglib..*.*(..) )")    public void pointcut(){}        @Around("pointcut()")    public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable{        System.out.println("method around start...");        pjp.proceed();        System.out.println("method around end...");    }    }

/Spring_AOP/src/cglib.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:context="http://www.springframework.org/schema/context"     xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://www.springframework.org/schema/beans                         http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                         http://www.springframework.org/schema/aop                         http://www.springframework.org/schema/aop/spring-aop-4.0.xsd                         http://www.springframework.org/schema/context                         http://www.springframework.org/schema/context/spring-context-4.0.xsd ">        <context:annotation-config></context:annotation-config>    <context:component-scan base-package="yuki.spring.aop.cglib"></context:component-scan>        <aop:aspectj-autoproxy></aop:aspectj-autoproxy>    </beans>

/Spring_AOP/src/yuki/spring/aop/cglib/UserServiceTest.java

package yuki.spring.aop.cglib;import org.junit.Test;import org.springframework.context.support.ClassPathXmlApplicationContext;public class UserServiceTest {    @Test    public void testSave() {                @SuppressWarnings("resource")        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("cglib.xml");        UserService service = (UserService) context.getBean("userService");        System.out.println(service.getClass());        service.save();        context.destroy();    }}

运行结果如下：

八月 31, 2014 11:14:17 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:14:17 CST 2014]; root of context hierarchy八月 31, 2014 11:14:17 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [cglib.xml]class yuki.spring.aop.cglib.UserService$$EnhancerBySpringCGLIB$$b8ea6837method around start...user saved...method around end...八月 31, 2014 11:14:19 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:14:17 CST 2014]; root of context hierarchy

4.xml：AOP
pointcut可以声明在aspect的里面或外面

eclipse：从源码视图切换到设计视图

在执行UserService.save()时，发现符合配置的切入点表达式
对应的是LogAspect.before()，于是先执行before，然后save()
可以直接指定pointcut，也可以在外部指定然后再引用它
如果使用第三方类的切面类逻辑，那么就必须要使用xml配置的方式

/Spring_AOP/src/yuki/spring/aop/xml/UserService.java

package yuki.spring.aop.xml;import org.springframework.stereotype.Component;@Component("userService")public class UserService {    public void save(){        System.out.println("user saved...");    }}

/Spring_AOP/src/yuki/spring/aop/xml/LogAspect.java

package yuki.spring.aop.xml;public class LogAspect {    public void before() {        System.out.println("method start...");    }}

/Spring_AOP/src/xml.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns:aop="http://www.springframework.org/schema/aop"    xmlns:context="http://www.springframework.org/schema/context"     xmlns="http://www.springframework.org/schema/beans"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://www.springframework.org/schema/beans                         http://www.springframework.org/schema/beans/spring-beans-4.0.xsd                         http://www.springframework.org/schema/aop                         http://www.springframework.org/schema/aop/spring-aop-4.0.xsd                         http://www.springframework.org/schema/context                         http://www.springframework.org/schema/context/spring-context-4.0.xsd ">        <context:annotation-config></context:annotation-config>    <context:component-scan base-package="yuki.spring.aop.xml"></context:component-scan>        <bean id="logAspect" class="yuki.spring.aop.xml.LogAspect"></bean>    <!--     <aop:config>        <aop:pointcut id="servicePointcut"                expression="execution( public * yuki.spring.aop.xml..*.*(..) )" />        <aop:aspect id="logAspect" ref="logAspect">            <aop:before method="before" pointcut-ref="servicePointcut"/>        </aop:aspect>    </aop:config>     -->    <aop:config>        <aop:aspect id="logAspect" ref="logAspect">            <aop:before method="before"                     pointcut="execution( public * yuki.spring.aop.xml..*.*(..) )"/>        </aop:aspect>    </aop:config></beans>

/Spring_AOP/src/yuki/spring/aop/xml/UserServiceTest.java

package yuki.spring.aop.xml;import org.junit.Test;import org.springframework.context.support.ClassPathXmlApplicationContext;public class UserServiceTest {    @Test    public void testSave() {                @SuppressWarnings("resource")        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("xml.xml");        UserService service = (UserService) context.getBean("userService");        service.save();        context.destroy();    }}

运行结果如下：

八月 31, 2014 11:19:01 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:19:01 CST 2014]; root of context hierarchy八月 31, 2014 11:19:01 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions信息: Loading XML bean definitions from class path resource [xml.xml]method start...user saved...八月 31, 2014 11:19:02 下午 org.springframework.context.support.ClassPathXmlApplicationContext doClose信息: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1637f22: startup date [Sun Aug 31 23:19:01 CST 2014]; root of context hierarchy

5.tomcat debug的热部署
在tomcat的jdk虚拟机参数中添加
-Dcom.sun.management.jmxremote=true

如果修改配置文件，使用了自定义标签的jsp页面，修改了注解，等等情况：还是要重启服务器的

在方法内部修改代码，不用重启服务器，这已经是很大的便捷了，

有兴趣的小伙伴们去研究功能更强大的热部署吧。。。。

目录结构：

本文参考了[尚学堂马士兵_Spring_AOP]的公开课程

更多好文请关注：http://www.cnblogs.com/kodoyang/

>*_*<

kongdongyang

2014/8/31

Spring面向切面 --- AspectJ --- 简单使用

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Spring面向切面 --- AspectJ --- 简单使用

Spring面向切面 --- AspectJ --- 简单使用

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