在本教程中，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。
注意
Spring AOP 中没有 AspectJ 支持，请阅读 内置 Spring AOP 例子。
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
