Spring 基于Aspectj的注解开发AOP(一)-前置通知@Before

缺乏、安全感 2022-03-02 18:24 563阅读 0赞

### **一、Aspectj 常用注解** ###

1、@Before 前置通知，相当于BeforeAdvice
            ps:在目标方法之前执行
            应用场景：如在保存之前进行权限校验，只有管理员身份才有权限保存；
        2、@AfterReturning 后置通知，相当于AfterReturningAdvice
            ps:在目标方法之后执行
            应用场景：如在删除一条记录时候，记录是谁什么时候删除的；
        3、@Around 环绕通知，相当于MethodInterceptor
            ps:在目标方法之前和之后执行，可以阻止目标方法执行
            应用场景：如事务处理，在目标方法之前开启事务，目标方法之后提交或回滚事务；
        4、@AfterThrowing 异常抛出通知，相当于ThrowAdvice
            ps：只会在目标方法有异常的情况下，才会执行
        5、@After 最终final通知，不管是否有异常，该通知都会执行；

###    **二、在通知中通过value属性定义切点** ###

在通知中通过value属性定义切点
    
    •通过execution函数，可以定义切点的方法切入
    
    •语法：
        –execution(<访问修饰符>?<返回类型><方法名>(<参数>)<异常>)
    
    •例如
        –匹配所有类public方法execution(public * *(..))
    
        –匹配指定包下所有类方法execution(* com.imooc.dao.*(..)) 
    
        -不包含子包–execution(* com.imooc.dao..*(..))  ..*表示包、子孙包下所有类
    
        –匹配指定类所有方法execution(* com.imooc.service.UserService.*(..))
    
        –匹配实现特定接口所有类方法    execution(* com.imooc.dao.GenericDAO+.*(..))
    
        –匹配所有save开头的方法 execution(* save*(..))

## 三、可以在方法中传入JoinPoint对象，用来获取切点信息(ps:案例中有介绍) ##

## **四、入门案例 ** ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70][]

### applicationContext.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: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">
    
        
        <aop:aspectj-autoproxy/>
    
        
        <bean id="ProductDao" class="com.lucifer.aspectj.demo.ProductDao"/>
    
        
        <bean id="MyAspectjAnno" class="com.lucifer.aspectj.demo.MyAspectjAnno"/>
    
    </beans>

###  ProductDao 目前类： ###

package com.lucifer.aspectj.demo;
    
    /**
     * @Author: Lucifer
     * @Date: 2019/3/21 00:28
     * @Description:
     */
    public class ProductDao {
    
        public void save(){
            System.out.println("保存商品");
        }
    
        public void update(){
            System.out.println("修改商品");
        }
    
        public void delete(){
            System.out.println("删除商品");
        }
    
        public void findOne(){
            System.out.println("查询一个商品");
        }
    
        public void findAll(){
            System.out.println("查询所有商品");
        }
    
    
    }

### MyAspectjAnno 切面类： ###

package com.lucifer.aspectj.demo;
    
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.annotation.Before;
    
    /**
     * @Author: Lucifer
     * @Date: 2019/3/21 00:31
     * @Description: 切面类
     */
    @Aspect
    public class MyAspectjAnno {
    
        @Before(value = "execution(* com.lucifer.aspectj.demo.ProductDao.*(..))")
        public void before(){
            System.out.println("前置通知==============================");
        }
    
    }

### test 测试类：  ###

package com.lucifer.aspectj.demo;
    
    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;
    
    /**
     * @Author: Lucifer
     * @Date: 2019/3/21 00:36
     * @Description:
     */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration("classpath:applicationContext.xml")
    public class Test {
    
        @Autowired
        private ProductDao productDao;
    
        @org.junit.Test
        public void demo1(){
            productDao.save();
            productDao.delete();
            productDao.findAll();
            productDao.findOne();
            productDao.update();
        }
    
    }

### 控制台打印： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 1][]

### 只匹配com.lucifer.aspectj.demo类下的save()方法： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 2][]

### 改变MyAspectjAnno类，将before方法添加JoinPoint 参数； ###

### **ps:可以在方法中传入JoinPoint对象，用来获取切点信息** ###

package com.lucifer.aspectj.demo;
    
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.annotation.Before;
    
    /**
     * @Author: Lucifer
     * @Date: 2019/3/21 00:31
     * @Description: 切面类
     */
    @Aspect
    public class MyAspectjAnno {
    
        @Before(value = "execution(* com.lucifer.aspectj.demo.ProductDao.save(..))")
        public void before(JoinPoint joinPoint){
            System.out.println("前置通知=============================="+joinPoint);
        }
    
    }

### 控制台打印： ###

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NDk1Nzg2_size_16_color_FFFFFF_t_70 3][]

### pmo.xml: ###

<dependencies>
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.12</version>
          <scope>test</scope>
        </dependency>
    
        
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-beans</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-expression</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
    
        
        <dependency>
          <groupId>aopalliance</groupId>
          <artifactId>aopalliance</artifactId>
          <version>1.0</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-aop</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
    
        
        <dependency>
          <groupId>org.aspectj</groupId>
          <artifactId>aspectjweaver</artifactId>
          <version>1.9.2</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-aspects</artifactId>
          <version>5.1.3.RELEASE</version>
        </dependency>
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.12</version>
          <scope>compile</scope>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-test</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-test</artifactId>
          <version>5.1.5.RELEASE</version>
        </dependency>
    
      </dependencies>
      
      <build>
        <finalName>spring-aspectj</finalName>
      </build>

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