首先,导入包:
首先,AOP联盟定义的类型分为:
前置通知 org.springframework.aop.MethodBeforeAdvice,在目标方法执行前实施增强(执行切面方法)
后置通知 org.springframework.aop.AfterReturningAdvice,在目标方法执行后实施增强(执行切面方法)
环绕通知 org.aopalliance.intercept.MethodInterceptor,在目标方法执行前后实施增强(执行切面方法)
异常抛出通知 org.springframework.aop.ThrowsAdvice,在方法抛出异常后实施增强(执行切面方法)
引介通知 org.springframework.aop.IntroductionInterceptor,在目标类中添加一些新的方法和属性
其中,环绕通知用的最多。
假设已有如下目标接口和目标类:
public interface UserService { void addUser(); String updateUser(); void deleteUser(); } public class UserServiceImpl implements UserService { @Override public void addUser() { System.out.println(" add user"); } @Override public String updateUser() { //int a = 1/0; System.out.println(" update user"); return "更新用户信息"; } @Override public void deleteUser() { System.out.println(" delete user"); } }
在此基础上,不修改源代码,在调用UserServiceImpl的实例方法前后,输出其他的信息。
新建一个切面类:
import org.aspectj.lang.JoinPoint; import org.aspectj.lang.ProceedingJoinPoint; public class MyAspect { //自定义前置通知方法 public void myBefor(JoinPoint joinPoint) { System.out.println("前置通知"); } /** * 自定义后置通知方法 * @param joinPoint * @param object 目标方法的返回值 */ public void myReturn(JoinPoint joinPoint, Object object) { System.out.println("后置通知,返回的值为:" + object); } //自定义环绕通知方法 public Object myAround(ProceedingJoinPoint joinPoint) throws Throwable { System.out.println("环绕前 通知"); Object object = joinPoint.proceed(); System.out.println("环绕后通知"); return object; } /** * 自定义异常抛出通知方法 * @param joinPoint * @param eThrowable 目标方法的异常 */ public void myThrowAble(JoinPoint joinPoint, Throwable eThrowable) { System.out.println("异常通知:" + eThrowable.getMessage()); } }
然后添加配置文件:
<?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.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> <bean id="userService" class="com.kye.d_aspect.a_xml.UserServiceImpl"></bean> <bean id="myAspect" class="com.kye.d_aspect.a_xml.MyAspect"></bean> <aop:config> <aop:aspect ref="myAspect"> <aop:pointcut expression="execution(* com.kye.d_aspect.a_xml.UserServiceImpl.*(..))" id="myCut" /> <aop:before method="myBefor" pointcut-ref="myCut" /> <aop:after-returning method="myReturn" pointcut-ref="myCut" returning="object"/> <aop:around method="myAround" pointcut="execution(* com.kye.d_aspect.a_xml.UserServiceImpl.update*(..))"/> <aop:after-throwing method="myThrowAble" pointcut-ref="myCut" throwing="eThrowable"/> </aop:aspect> </aop:config> </beans>
切入点表达式可以参考这里。
然后测试类:
import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MyTest { @Test public void test1() { String path = "com/kye/d_aspect/a_xml/beans.xml"; ApplicationContext applicationContext = new ClassPathXmlApplicationContext(path); UserService userService = applicationContext.getBean("userService", UserService.class); userService.addUser(); userService.updateUser(); userService.deleteUser(); } }
最后输出:
befor... c_spring_aop add user after... befor... c_spring_aop update user after... befor... c_spring_aop delete user after...