一、简介 1、AOP用在哪些方面:AOP能够将那些与业务无关,却为业务模块所共同调用的逻辑或责任,例如事务处理、日志管理、权限控制,异常处理等,封装起来,便于减少系统的重复代码,降低模块间的耦合度,并有利于未来的可操作性和可维护性。 2、AOP中的概念: Aspect(切面):指横切性关注点的抽象即为切面,它与类相似,只是两者的关注点不一样,类是对物体特征的抽象,而切面是横切性关注点的抽象. joinpoint(连接点):所谓连接点是指那些被拦截到的点(可以是方法、属性、或者类的初始化时机(可以是Action层、Service层、dao层))。在spring中,这些点指的是方法,因为spring只支持方法类型的连接点,实际上joinpoint还可以是field或类构造器) Pointcut(切入点):所谓切入点是指我们要对那些joinpoint进行拦截的定义,也即joinpoint的集合. Advice(通知):所谓通知是指拦截到joinpoint之后所要做的事情就是通知.通知分为前置通知,后置通知,异常通知,最终通知,环绕通知 Target(目标对象):代理的目标对象 Weave(织入):指将aspects应用到target对象并导致proxy对象创建的过程称为织入. Introduction(引入):在不修改类代码的前提下, Introduction可以在运行期为类动态地添加一些方法或Field.
3、AOP带来的好处::降低模块的耦合度;使系统容易扩展;更好的代码复用性
二、通过注解方式实现Spring的AOP
1.定义业务类
接口:
[java]
package cn.slimsmart.spring.demo.aop;
public interface UserService {
String save(String name);
String update(String name);
String delete(String name);
}
实现:
[java]
package cn.slimsmart.spring.demo.aop;
import org.springframework.stereotype.Service;
@Service <span style="font-family: Arial, Helvetica, sans-serif;">//使用自动注解的方式实例化并初始化该类</span>
public class UserServiceImpl implements UserService{
@Override
public String save(String name) {
System.out.println("--------save");
return "save";
}
@Override
public String update(String name) {
System.out.println("--------update");
System.out.println(1/0);
return "update";
}
@Override
public String delete(String name) {
System.out.println("--------delete");
return "delete";
}
}
2.定义切面类
[java]
package cn.slimsmart.spring.demo.aop;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;
//@Aspect : 标记为切面类
//@Pointcut : 指定匹配切点集合
//@Before : 指定前置通知,value中指定切入点匹配
//@AfterReturning :后置通知,具有可以指定返回值
//@AfterThrowing :异常通知
//@Around 环绕通知 环绕通知的方法中一定要有ProceedingJoinPoint 参数,与Filter中的 doFilter方法类似
//注意:前置/后置/异常通知的函数都没有返回值,只有环绕通知有返回值
@Component //使用自动注解的方式实例化并初始化该类
@Aspect
public class TestInterceptor {
//如果要设置多个切点可以使用 || 拼接
@Pointcut("execution(* cn.slimsmart.spring.demo.aop.UserServiceImpl.*(..))")
private void anyMethod() {
}// 定义一个切入点
@Before(value="anyMethod()")
public void doBefore(JoinPoint joinPoint) {
System.out.println("前置通知");
}
@AfterReturning(value="anyMethod()",returning="result")
public void doAfter(JoinPoint jp, String result) {
System.out.println("后置通知");
}
@After("anyMethod()")
public void after() {
System.out.println("最终通知");
}
@AfterThrowing(value="execution(* cn.slimsmart.spring.demo.aop.*.*(..))",throwing="e")
public void doAfterThrow(JoinPoint joinPoint, Throwable e) {
System.out.println("异常通知");
}
@Around("execution(* cn.slimsmart.spring.demo.aop.*.*(..))")
public Object doBasicProfiling(ProceedingJoinPoint joinPoint) throws Throwable {
System.out.println("进入环绕通知");
System.out.println("目标类名称:"+joinPoint.getTarget().getClass().getName());
System.out.println("方法名称:"+joinPoint.getSignature().getName());
System.out.println("方法参数:"+joinPoint.getArgs());
System.out.println("staticPart:"+ joinPoint.getStaticPart().toShortString());
System.out.println("kind:"+joinPoint.getKind());
System.out.println("sourceLocation:"+joinPoint.getSourceLocation());
Object object = joinPoint.proceed();// 执行该方法
System.out.println("退出方法");
return object;
}
}
3.applicationContext.xml配置
[html]
<?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"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">
<context:component-scan base-package="cn.slimsmart.spring.demo" />
<!-- 打开aop 注解 -->
<aop:aspectj-autoproxy proxy-target-class="true"/>
</beans>
4.单元测试类
[java]
package cn.slimsmart.spring.demo;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import cn.slimsmart.spring.demo.aop.UserService;
@RunWith(SpringJUnit4ClassRunner.class)//让junit工作在spring环境中
@ContextConfiguration(locations={"classpath:applicationContext.xml"})
public class SpringTest{
@Autowired
UserService userService;
@Test
public void testStart(){
System.out.println("启动服务");
userService.delete("abc123");
System.out.println("====================");
userService.update("aaa");
}
}
运行结果:执行update抛异常:/ by zero
[plain]
注:pom.xml引入的jar包
[html]
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.slimsmart.spring.demo</groupId>
<artifactId>spring-demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
<!-- <dependency> -->
<!-- <groupId>org.springframework</groupId> -->
<!-- <artifactId>spring-tx</artifactId> -->
<!-- <version>4.1.4.RELEASE</version> -->
<!-- </dependency> -->
<!-- <dependency> -->
<!-- <groupId>org.springframework</groupId> -->
<!-- <artifactId>spring-jdbc</artifactId> -->
<!-- <version>4.1.4.RELEASE</version> -->
<!-- </dependency> -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>4.1.4.RELEASE</version>
</dependency>
<dependency>
<groupId>aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.5.4</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.8.4</version>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>3.1</version>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib-nodep</artifactId>
<version>3.1</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
</project>
若不使用注解的方式,使用schema xml配置(也可以基于spring接口方式实现)的方式,如下参考:
[html]
<aop:config>
<aop:aspect id="businessAspect" ref="testInterceptor">
<!-- 配置指定切入的对象 -->
<aop:pointcut id="point_cut" expression="execution(* cn.slimsmart.spring.demo.aop.UserServiceImpl.*(..))" />
<!-- 前置通知 -->
<aop:before method="doBefore" pointcut-ref="point_cut" />
<!-- 后置通知 returning指定返回参数 -->
<aop:after-returning method="doAfter"
pointcut-ref="point_cut" returning="result" />
<aop:around method="doAround" pointcut-ref="point_cut"/>
<aop:after-throwing method="doThrow" pointcut-ref="point_cut" throwing="e"/>
</aop:aspect>
</aop:config>