Spring学习(十八)----- Spring AOP+AspectJ注解实例

我们将向你展示如何将AspectJ注解集成到Spring AOP框架。在这个Spring AOP+ AspectJ 示例中，让您轻松实现拦截方法。

常见AspectJ的注解：

@Before – 方法执行前运行
@After – 运行在方法返回结果后
@AfterReturning – 运行在方法返回一个结果后，在拦截器返回结果。
@AfterThrowing – 运行方法在抛出异常后，
@Around – 围绕方法执行运行，结合以上这三个通知。

1. 目录结构

看到这个例子的目录结构。

2. Spring Beans

普通 bean 中有几个方法，后来通过 AspectJ 注解拦截。

package com.yiibai.customer.bo;

public interface CustomerBo {

    void addCustomer();

    String addCustomerReturnValue();

    void addCustomerThrowException() throws Exception;

    void addCustomerAround(String name);

}

package com.yiibai.customer.bo.impl;

import com.yiibai.customer.bo.CustomerBo;

public class CustomerBoImpl implements CustomerBo {

    public void addCustomer(){

        System.out.println("addCustomer() is running ");

    }

    public String addCustomerReturnValue(){

        System.out.println("addCustomerReturnValue() is running ");

        return "abc";

    }

    public void addCustomerThrowException() throws Exception {

        System.out.println("addCustomerThrowException() is running ");

        throw new Exception("Generic Error");

    }

    public void addCustomerAround(String name){

        System.out.println("addCustomerAround() is running, args : " + name);

    }

}

4. 启用AspectJ

在 Spring 配置文件，把“<aop:aspectj-autoproxy />”，并定义Aspect(拦截)和普通的bean。

File : applicationContext.xml

<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-3.0.xsd

    http://www.springframework.org/schema/aop

    http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">

    <aop:aspectj-autoproxy />

    <bean id="customerBo" class="com.yiibai.customer.bo.impl.CustomerBoImpl" />

    <!-- Aspect -->

    <bean id="logAspect" class="com.yiibai.aspect.LoggingAspect" />

</beans>

4. AspectJ @Before

在下面例子中，logBefore()方法将在 customerBo接口的 addCustomer()方法的执行之前被执行。

AspectJ的“切入点”是用来声明哪种方法将被拦截，应该参考Spring AOP切入点指南，支持切入点表达式的完整列表。

File : LoggingAspect.java

package com.yiibai.aspect;

import org.aspectj.lang.JoinYiibai;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

@Aspect

public class LoggingAspect {

    @Before("execution(* com.yiibai.customer.bo.CustomerBo.addCustomer(..))")

    public void logBefore(JoinYiibai joinYiibai) {

        System.out.println("logBefore() is running!");

        System.out.println("hijacked : " + joinYiibai.getSignature().getName());

        System.out.println("******");

    }

}

运行

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");

customer.addCustomer();

输出结果

logBefore() is running!

hijacked : addCustomer

******

addCustomer() is running

5. AspectJ @After

在下面例子中，logAfter()方法将在 customerBo 接口的 addCustomer()方法的执行之后执行。

File : LoggingAspect.java

package com.yiibai.aspect;

import org.aspectj.lang.JoinYiibai;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.After;

@Aspect

public class LoggingAspect {

    @After("execution(* com.yiibai.customer.bo.CustomerBo.addCustomer(..))")

    public void logAfter(JoinYiibai joinYiibai) {

        System.out.println("logAfter() is running!");

        System.out.println("hijacked : " + joinYiibai.getSignature().getName());

        System.out.println("******");

    }

}

运行它

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");

customer.addCustomer();

输出结果

addCustomer() is running

logAfter() is running!

hijacked : addCustomer

******

6. AspectJ @AfterReturning

在下面例子中，logAfterReturning()方法将在 customerBo 接口的addCustomerReturnValue()方法执行之后执行。此外，还可以截取返回的值使用“returning”属性。

要截取返回的值，对“returning”属性(结果)的值必须用相同的方法参数(结果)。

File : LoggingAspect.java

package com.yiibai.aspect;

import org.aspectj.lang.JoinYiibai;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.AfterReturning;

@Aspect

public class LoggingAspect {

   @AfterReturning(

      pointcut = "execution(* com.yiibai.customer.bo.CustomerBo.addCustomerReturnValue(..))",

      returning= "result")

   public void logAfterReturning(JoinYiibai joinYiibai, Object result) {

    System.out.println("logAfterReturning() is running!");

    System.out.println("hijacked : " + joinYiibai.getSignature().getName());

    System.out.println("Method returned value is : " + result);

    System.out.println("******");

   }

}

运行它

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");

    customer.addCustomerReturnValue();

输出结果

addCustomerReturnValue() is running

logAfterReturning() is running!

hijacked : addCustomerReturnValue

Method returned value is : abc

******

7. AspectJ @AfterReturning

在下面的例子中，如果 customerBo 接口的addCustomerThrowException()方法抛出异常logAfterThrowing()方法将被执行。

File : LoggingAspect.java

package com.yiibai.aspect;

import org.aspectj.lang.JoinYiibai;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.AfterThrowing;

@Aspect

public class LoggingAspect {

   @AfterThrowing(

      pointcut = "execution(* com.yiibai.customer.bo.CustomerBo.addCustomerThrowException(..))",

      throwing= "error")

    public void logAfterThrowing(JoinYiibai joinYiibai, Throwable error) {

    System.out.println("logAfterThrowing() is running!");

    System.out.println("hijacked : " + joinYiibai.getSignature().getName());

    System.out.println("Exception : " + error);

    System.out.println("******");

    }

}

运行它

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");

customer.addCustomerThrowException();

输出结果

addCustomerThrowException() is running

logAfterThrowing() is running!

hijacked : addCustomerThrowException

Exception : java.lang.Exception: Generic Error

******

Exception in thread "main" java.lang.Exception: Generic Error

    //...

8. AspectJ @Around

在下面例子中，logAround()方法将在customerBo接口的addCustomerAround()方法执行之前执行，必须定义“joinYiibai.proceed();” 控制何时拦截器返回控制到原来的addCustomerAround()方法。

File : LoggingAspect.java

package com.yiibai.aspect;

import org.aspectj.lang.ProceedingJoinYiibai;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Around;

@Aspect

public class LoggingAspect {

   @Around("execution(* com.yiibai.customer.bo.CustomerBo.addCustomerAround(..))")

   public void logAround(ProceedingJoinYiibai joinYiibai) throws Throwable {

    System.out.println("logAround() is running!");

    System.out.println("hijacked method : " + joinYiibai.getSignature().getName());

    System.out.println("hijacked arguments : " + Arrays.toString(joinYiibai.getArgs()));

    System.out.println("Around before is running!");

    joinYiibai.proceed(); //continue on the intercepted method

    System.out.println("Around after is running!");

    System.out.println("******");

   }

}

运行它

CustomerBo customer = (CustomerBo) appContext.getBean("customerBo");

customer.addCustomerAround("yiibai");

输出结果

logAround() is running!

hijacked method : addCustomerAround

hijacked arguments : [yiibai]

Around before is running!

addCustomerAround() is running, args : yiibai

Around after is running!

******

总结

它总是建议采用最少 AspectJ 注解。这是关于Spring AspectJ 的一篇相当长的文章。进一步的解释和例子，请访问下面的参考链接。

下载源代码 – http://pan.baidu.com/s/1boo4f9P