AOP:面向切面編程
功能:在不改變原有代碼的基礎之上,通過Spring爲原有代碼做功能增強。降低業務邏輯耦合度,提高程序可用性。
配置流程:
(1)添加Maven依賴
(2)寫需要添加增強功能的業務代碼
(3)寫增強類
(4)調整配置文件app.xml
(5)使用
具體過程:
(1)依賴(AOP+aspectj)
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.9.1</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjtools</artifactId>
<version>1.9.1</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.1</version>
</dependency>
<dependency>
<groupId>aopalliance</groupId>
<artifactId>aopalliance</artifactId>
<version>1.0</version>
</dependency>
(2)業務代碼
public class UserController {
public void fun(){
System.out.println("公司的原古代碼……");
}
}
(3)增強類
//放置所有的增強功能
@Component
@Aspect
public class BDAdvice {
@Before("execution(public void com.zparkep.controller.UserController.fun())")
public void before(){
System.out.println("before advice");
}
}
(4)調整配置文件spring.xml
?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:context="http://www.springframework.org/schema/context"
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/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<context:component-scan base-package="com.zparkep"/>
<aop:aspectj-autoproxy/>
</beans>
(5)使用
@RunWith(SpringRunner.class)
@ContextConfiguration("classpath:app.xml")
public class AdviceTest {
//對UserController進行增強測試
@Autowired
private UserController userController;
@Test
public void fun(){
userController.fun();
}
}
結果:
成功
注:@Before("execution(public void com.zparkep.controller.UserController.fun())")表示對public類型的返回值爲void的 com.zparkep.controller包下的UserController類下的fun方法做前置增強。
設對public類型的返回值爲String的 com.zparkep.controller包下的所有類下的所有方法【參數不確定】做前置增強,則註解爲@Before("execution(public String com.zparkep.controller.*.*(..))")
若多個增強方法對具有同一規則的方法做增強,根據DRY原則,需要提取規則,可使用@Pointcut()註解,舉例。
爲UserController類下的所有方法添加前置增強和後置增強:
@Aspect
@Component
@Log
public class BDadvice {
@Pointcut("execution(public void com.zparkep.controller.UserController.*())")
public void fun(){
}
@After("fun())")
public void after(){
log.info("after advice");
}
@Before("fun()")
public void before(){
System.out.println("before advice");
}
}