Spring AOP配置

一、XML配置方式

1.创建一个Service类

package com.spring.useage.service;

public class UserService {

    public void save() {
        System.out.println("save a user.");
    }
    
    public void findById(String id) {
        System.out.println("find a user by id");
    }
    
    public void deleteUser() {
        System.out.println("a user is deleted.");
    }
}

2.创建一个切面类

package com.spring.aop;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.JoinPoint;

public class SecurityCheck {
    public final static Log log = LogFactory.getLog(SecurityCheck.class);
    
    public void check() {
        log.info("权限校验。。。");
    }
    
    public void addLog(JoinPoint joinPoint) {
        log.info("添加日志。。。");
        String methodName = joinPoint.getSignature().getName();
        log.info("方法名：" + methodName);
        log.info("方法参数：");
        Object[] args = joinPoint.getArgs();
        for (Object obj : args) {
            log.info(obj);
        }
    }
}

3.XML配置的方式如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">

    <bean id="securityCheck" class="com.spring.aop.SecurityCheck"></bean>
    <bean id="userService" class="com.spring.useage.service.UserService"></bean>
    <aop:config>
        <aop:aspect id="myAop" ref="securityCheck">
            <aop:pointcut id="target"
                expression="execution(* com.spring.useage.service.*.*(..))" />
            <aop:before method="check" pointcut-ref="target" />
            <aop:after method="addLog" pointcut-ref="target" />
        </aop:aspect>
    </aop:config>
</beans>

execution(* com.spring.useage.service.*.*(..))说明：

第1个*：表示所有返回值类型

第2个*：表示com.spring.useage.service下的所有类

第3个*：表示所有方法

最后的..：表示任意参数

需要引入的包如下：

4.测试类如下：

package com.spring.aop;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.spring.useage.service.UserService;

public class AopTest {

    /**
     *
     * @author qincd
     * @date Nov 24, 2014 6:30:00 PM
     */
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
        UserService us = ac.getBean(UserService.class);
        us.save();
        us.findById("admin");
        us.deleteUser();
    }

}

执行AopTest，输出如下：

2014-11-25 9:59:10 org.springframework.context.support.AbstractApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@14d3343: startup date [Tue Nov 25 09:59:10 CST 2014]; root of context hierarchy
2014-11-25 9:59:10 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
2014-11-25 9:59:10 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
信息: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1b3f829: defining beans [securityCheck,userService,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.aop.aspectj.AspectJPointcutAdvisor#0,org.springframework.aop.aspectj.AspectJPointcutAdvisor#1,target]; root of factory hierarchy
2014-11-25 9:59:10 com.spring.aop.SecurityCheck check
信息: 权限校验。。。
save a user.
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 添加日志。。。
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法名：save
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法参数：
2014-11-25 9:59:10 com.spring.aop.SecurityCheck check
信息: 权限校验。。。
find a user by id
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 添加日志。。。
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法名：findById
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法参数：
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: admin
2014-11-25 9:59:10 com.spring.aop.SecurityCheck check
信息: 权限校验。。。
a user is deleted.
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 添加日志。。。
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法名：deleteUser
2014-11-25 9:59:10 com.spring.aop.SecurityCheck addLog
信息: 方法参数：

二、Annotation方式

1.UserService类加上@Service注解

package com.spring.useage.service;

import org.springframework.stereotype.Service;

@Service
public class UserService {

    public void save() {
        System.out.println("save a user.");
    }
    
    public void findById(String id) {
        System.out.println("find a user by id");
    }
    
    public void deleteUser() {
        System.out.println("a user is deleted.");
    }
}

2.SecurityCheck加上@Aspect和@Component注解

package com.spring.aop;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class SecurityCheck {
    public final static Log log = LogFactory.getLog(SecurityCheck.class);
    
    @Before("execution (* com.spring.**.service.*.*(..))")
    public void check() {
        log.info("权限校验。。。");
    }
    
    @After("execution (* com.spring.**.service.*.*(..))")
    public void addLog(JoinPoint joinPoint) {
        log.info("添加日志。。。");
        String methodName = joinPoint.getSignature().getName();
        log.info("方法名：" + methodName);
        log.info("方法参数：");
        Object[] args = joinPoint.getArgs();
        for (Object obj : args) {
            log.info(obj);
        }
    }
}

1、@Aspect：意思是这个类为切面类

2、@Componet：因为作为切面类需要Spring管理起来，所以在初始化时就需要将这个类初始化加入Spring的管理；

3、@Befoe：切入点的逻辑(Advice)

4、execution…:切入点语法

applicationContext.xml加入aspectj自动代理，并启用注解。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
 http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <aop:aspectj-autoproxy />
    <context:annotation-config />
    <context:component-scan base-package="com.spring" />
</beans>

当多个Advice个有相同的织入点。那么我们可以定义一个织入点集合，在需要使用的地方，调用就可以了。

如：

package com.spring.aop;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
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
@Component
public class SecurityCheck {
    public final static Log log = LogFactory.getLog(SecurityCheck.class);
    
    @Before("myPointCut()")
    public void check() {
        log.info("权限校验。。。");
    }
    
    @After("myPointCut()")
    public void addLog(JoinPoint joinPoint) {
        log.info("添加日志。。。");
        String methodName = joinPoint.getSignature().getName();
        log.info("方法名：" + methodName);
        log.info("方法参数：");
        Object[] args = joinPoint.getArgs();
        for (Object obj : args) {
            log.info(obj);
        }
    }
    
    @AfterReturning("myPointCut()")
    public void afterReturning() {
        log.info("method after returning...");
    }
    
    @Around("myPointCut()")
    public void around(ProceedingJoinPoint pjp) throws Throwable {
        log.info("method around start...");
        pjp.proceed();
        log.info("method around end...");
    }
    
    @AfterThrowing("myPointCut()")
    public void afterThrowing(JoinPoint joinPoint) {
        log.error(joinPoint.getSignature().getName() + "执行异常：" );
    }
    
    @Pointcut("execution (* com.spring..service.*.*(..))")
    public void myPointCut() {}
}

注意：那个空方法，只是为了给Pointcut起个名字，以方便别处使用

AOP实现动态代理注意

因为Spring要实现AOP(面向切面编程)，需要加入切面逻辑的类就会生成动态代理。在动态代理类中加入切面类从而实现面向切面编程，但生成动态代理存在以下注意事项：

1、 被动态代理的类如果实现了某一个接口，那么Spring就会利用JDK类库生成动态代理。

2、 如果被动态代理的类没有实现某一个接口，那么Spring就会利用CGLIB类库直接修改二进制码来生成动态代理(因为利用JDK生成动态代理的类必须实现一个接口)，需要在项目中引用CGLIB类库

参考：http://blog.csdn.net/yuqinying112/article/details/7335416