Spring AOP+AspectJ註解實例

在本教程中，我們將向你展示如何將AspectJ註解集成到Spring AOP框架。在這個Spring AOP+ AspectJ 示例中，讓您輕鬆實現攔截方法。

常見AspectJ的註解：

1. @Before – 方法執行前運行
2. @After – 運行在方法返回結果後
3. @AfterReturning – 運行在方法返回一個結果後，在攔截器返回結果。
4. @AfterThrowing – 運行方法在拋出異常後，
5. @Around – 圍繞方法執行運行，結合以上這三個通知。

注意

Spring AOP 中沒有 AspectJ 支持，請閱讀 內置 Spring AOP 例子。

1. 目錄結構

看到這個例子的目錄結構。

2. Spring Beans

普通 bean 中有幾個方法，後來通過 AspectJ 註解攔截。

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. 啓用AspectJ

在 Spring 配置文件，把「<aop:aspectj-autoproxy />」，並定義Aspect(攔截)和普通的bean。

File : applicationContext.xml

<aop:aspectj-autoproxy />

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

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

4. AspectJ @Before

在下面例子中，logBefore()方法將在 customerBo接口的 addCustomer()方法的執行之前被執行。

AspectJ的「切入點」是用來聲明哪種方法將被攔截，應該參考 Spring AOP切入點指南，支持切入點表達式的完整列表。

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("\*\*\*\*\*\*");
}

}

運行

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

輸出結果

logBefore() is running!
hijacked : addCustomer
******
addCustomer() is running

5. AspectJ @After

在下面例子中，logAfter()方法將在 customerBo 接口的 addCustomer()方法的執行之後執行。

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("\*\*\*\*\*\*");

}

}

運行它

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

輸出結果

addCustomer() is running
logAfter() is running!
hijacked : addCustomer
******

6. AspectJ @AfterReturning

在下面例子中，logAfterReturning()方法將在 customerBo 接口的addCustomerReturnValue()方法執行之後執行。此外，還可以截取返回的值使用「returning」屬性。

要截取返回的值，對「returning」屬性(結果)的值必須用相同的方法參數(結果)。

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("\*\*\*\*\*\*");

}
}

運行它

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

輸出結果

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()方法拋出異常logAfterThrowing()方法將被執行。

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("\*\*\*\*\*\*");

}

}

運行它

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

輸出結果

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()方法將在customerBo接口的addCustomerAround()方法執行之前執行， 必須定義「joinYiibai.proceed();」 控制何時攔截器返回控制到原來的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("\*\*\*\*\*\*");

}

}

運行它

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

輸出結果

logAround() is running!
hijacked method : addCustomerAround
hijacked arguments : [yiibai]
Around before is running!
addCustomerAround() is running, args : yiibai
Around after is running!
******

總結

它總是建議採用最少 AspectJ 註解。這是關於Spring AspectJ 的一篇相當長的文章。進一步的解釋和例子，請訪問下面的參考鏈接。

下載源代碼 –  http://pan.baidu.com/s/1boo4f9P