Spring中实现AOP的功能

绝地灬酷狼 2024-04-05 07:15 78阅读 0赞

> [Java知识点总结：想看的可以从这里进入][Java]

#### 目录 ####

*   *   *  13.4、AOP的实现
         *   *  13.4.1、通过XML实现
             *  13.4.2、通过注解实现
             *  13.4.3、api接口实现
             *  13.4.4、ProxyFactoryBean

#### 13.4、AOP的实现 ####

AOP它是一种思想，并非是Spring 特有，Spring只是支持了AOP的框架之一，它是方法级别的AOP框架，主要是以某个类的某个方法为连接点，实现动态代理。

在Spring中有4种方式实现AOP，在使用时基本是以 @AspectJ 注解 为主，XML配置为辅实现AOP。

1.  通过ProxyFactory和对应接口
2.  `XML配置AOP`
3.  `@AspectJ注解实现AOP`
4.  使用 Aspectj 注入切面

<dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>6.0.3</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>5.3.21</version>
    </dependency>
    
    
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>6.0.3</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aspects</artifactId>
        <version>5.3.21</version>
    </dependency>

##### 13.4.1、通过XML实现 #####

*  创建dao，模拟从数据库中获取数据
    
        @Bean("userList")
        public List<User> getUserList(){
              
            List<User> userList = new ArrayList<>();
            userList.add(new User(1,"用户1","123456",false));
            userList.add(new User(2,"用户2","234567",false));
            userList.add(new User(3,"用户3","345678",false));
            userList.add(new User(4,"用户4","456789",false));
            userList.add(new User(5,"用户5","567890",false));
            return userList;
        }
    
        @Repository
        public class ProxyTestUserDao {
              
            @Resource
            private List<User> userList;
        
            //改
            public void update(User user) {
              
                boolean exists = true;
                for (int i=0; i<userList.size(); i++){
              
                    if(user.getUserId().equals(userList.get(i).getUserId())){
              
                        exists = false;
                        userList.set(i,user);
                        break;
                    }
                }
                if(exists){
              
                    System.out.println("没有此用户");
                }
            }
            //删
            public void delete(int id) {
              
                boolean exists = false;
                for (int i=0; i<userList.size(); i++){
              
                    if(id == userList.get(i).getUserId()){
              
                        exists = true;
                        userList.remove(i);
                        break;
                    }
                }
                if(!exists){
              
                    System.out.println("没有此用户");
                }
            }
            //查
            public User select(int id) {
              
                for (User user : userList) {
              
                    if (id == user.getUserId()) {
              
                        return user;
                    }
                }
                return null;
            }
            public List<User> selectAll() {
              
                return userList;
            }
            //增加
            public void insert(User user) {
              
                int id = userList.get(userList.size()-1).getUserId();
                id += 1;
                user.setUserId(id);
                userList.add(user);
                System.out.println("增加成功");
            }
        
        
        }
 *  创建service，用其作为连接点
    
        @Service
        public class ProxyTestUserServiceImpl implements ProxyTestUserService {
              
            @Autowired
            private ProxyTestUserDao proxyTestUserDao;
        
            @Override
            public void update(User user) {
              
                proxyTestUserDao.update(user);
            }
            @Override
            public void delete(int id) {
              
                proxyTestUserDao.delete(id);
            }
            @Override
            public User select(int id) {
              
                return proxyTestUserDao.select(id);
            }
            @Override
            public List<User> selectAll() {
              
                return proxyTestUserDao.selectAll();
            }
            @Override
            public void insert(User user) {
              
                proxyTestUserDao.insert(user);
            }
        }
 *  创建切面
    
        public class UserServiceInterceptor implements Interceptor {
              
            /**
             * 前置通知
            */
            public void before(JoinPoint joinPoint) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                //获取目标方法的实参信息
                String args = Arrays.toString(joinPoint.getArgs());
                System.out.println("前置通知，方法名："+methodName+"，参数："+args);
            }
            /**
             * 后置通知
             */
            public void after(JoinPoint joinPoint) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("后置通知，方法名："+methodName);
            }
        
            /**
             * 返回通知
             */
            public void afterReturning(JoinPoint joinPoint, Object result) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("返回通知，方法名："+methodName);
            }
        
            /**
             * 异常通知
             */
            public void afterThrowing(JoinPoint joinPoint, Throwable ex) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("异常通知，方法名："+methodName+"，异常："+ex);
            }
        
            /**
             * 环绕通知
             */
            public Object around(ProceedingJoinPoint point){
              
                System.out.println("环绕通知开始");
                //获取连接点的名字
                String methodName = point.getSignature().getName();
                //获取连接点的参数
                String args = Arrays.toString(point.getArgs());
                System.out.println("环绕通知，方法名："+methodName+"，参数："+args);
                Object o = null;
                try {
              
                    System.out.println("环绕通知：目标对象方法执行之前");
                    //目标对象（连接点）方法的执行
                    o = point.proceed();
                    System.out.println("环绕通知：目标对象方法返回值之后");
                } catch (Throwable throwable) {
              
                    throwable.printStackTrace();
                    System.out.println("环绕通知：目标对象方法出现异常时");
                } finally {
              
                    System.out.println("环绕通知：目标对象方法执行完毕");
                }
                return  o;
            }
        }
 *  在XML文件中配置
    
        <?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
                    https://www.springframework.org/schema/aop/spring-aop.xsd">
        	
            
            <bean id="interceptor" class="com.yu.spring.aspect.UserServiceInterceptor"/>
            <aop:config>
                
                <aop:aspect id="interceptor" ref="interceptor">
                    
                    <aop:pointcut id="service" expression="execution(* com.yu.spring.service.impl.UserServiceImpl.*(..))"/>
                    
                    <aop:before method="before" pointcut-ref="service"/>
                    
                    <aop:after-returning method="afterReturning" returning="result" pointcut-ref="service"/>
                    
                    <aop:after method="after" pointcut-ref="service"/>
                    
                    <aop:after-throwing method="afterThrowing" throwing="ex" pointcut-ref="service"/>
                    
                    <aop:around method="around" pointcut-ref="service"/>
                </aop:aspect>
        
            </aop:config>
        </beans>
 *  测试
    
    ![image-20230330113659918][]

##### 13.4.2、通过注解实现 #####

实现AOP的主流方式，它的常用注解：

1、@Aspect：用于表明一个类为切面
    2、@Before("execution(* com.yu.service.impl.UserServiceImpl.*(..))"):将一个方法表示为前置通知，并设置切入点
    3、@After("execution()")：后置通知
    4、@AfterThrowing("execution()")：发生异常后执行
    5、@AfterReturning("execution()")：无异常时执行
    6、@Around：环绕通知
    	切点：execution()表达式
        execution：执行真实对象的方法时触发
        *：任意返回类型的方法
        com.yu.service.impl.UserServiceImpl：真实类的全限定名
        *：写真实对象中具体拦截的方法（*是所有）
        (..)：任意参数

Aspectj的指示器
    1、arg():限制连接点匹配参数为指定类型
    2、@args()：限制连接点匹配参数为指定注解标注的执行方法
    3、execution：匹配连接点，最常用
    4、this()：限制连接点匹配AOP代理的bean，引用为指定类型的类
    5、target：限制连接点匹配被代理对象为指定类型
    6、within():限制连接点匹配的包
    7、annotation：限制匹配带有指定注解的连接点

*  Service、dao等不变
 *  创建切面，使用上面的几种注解
    
        @Aspect
        @Component
        public class UserServiceImplAspect {
              
            /**
             * 前置通知
             */
            @Before("execution(* com.yu.spring.service.impl.ProxyTestUserServiceImpl.*(..))")
            public void before(JoinPoint joinPoint) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                //参数
                String args = Arrays.toString(joinPoint.getArgs());
                System.out.println("前置通知（注解），方法名："+methodName+"，参数："+args);
            }
        
            /**
             * 后置通知
             */
            @After("execution(* com.yu.spring.service.impl.ProxyTestUserServiceImpl.*(..))")
            public void after(JoinPoint joinPoint) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("后置通知（注解），方法名："+methodName);
            }
        
        
            /**
             * 返回通知
             */
            @AfterReturning(value = "execution(* com.yu.spring.service.impl.ProxyTestUserServiceImpl.*(..))" , returning = "result")
            public void afterReturning(JoinPoint joinPoint, Object result) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("返回通知（注解），方法名："+methodName);
            }
        
            /**
             * 异常通知
             */
            @AfterThrowing(value ="execution(* com.yu.spring.service.impl.ProxyTestUserServiceImpl.*(..))", throwing = "ex")
            public void afterThrowing(JoinPoint joinPoint, Throwable ex) {
              
                //获取连接点的名字
                String methodName = joinPoint.getSignature().getName();
                System.out.println("异常通知（注解），方法名："+methodName+"，异常："+ex);
            }
        
            /**
             * 环绕通知
             */
            @Around("execution(* com.yu.spring.service.impl.ProxyTestUserServiceImpl.*(..))")
            public Object around(ProceedingJoinPoint point){
              
                System.out.println("环绕通知开始（注解）");
                String methodName = point.getSignature().getName();
                String args = Arrays.toString(point.getArgs());
                System.out.println("环绕通知（注解），方法名："+methodName+"，参数："+args);
                Object o = null;
                try {
              
                    System.out.println("环绕通知（注解）：目标对象方法执行之前");
                    //目标对象（连接点）方法的执行
                    o = point.proceed();
                    System.out.println("环绕通知（注解）：目标对象方法返回值之后");
                } catch (Throwable throwable) {
              
                    throwable.printStackTrace();
                    System.out.println("环绕通知（注解）：目标对象方法出现异常时");
                } finally {
              
                    System.out.println("环绕通知（注解）：目标对象方法执行完毕");
                }
                return  o;
            }
        }
 *  在主配置类使用注解开启aop
    
        @Configuration
        @ComponentScan("com.yu.spring")
        //支持处理标记有 AspectJ 的@Aspect注释的组
        @EnableAspectJAutoProxy
        public class AOPConfig {
              
            
        }
 *  测试，通过配置类
    
    ![image-20230330114336341][]

##### 13.4.3、api接口实现 #####

使用Spring的aip接口实现：

1.  前置通知 org.springframework.aop.MethodBeforeAdvice
2.  后置通知 org.springframework.aop.AfterReturningAdvice
3.  环绕通知 org.aopalliance.intercept.MethodInterceptor
4.  异常抛出通知 org.springframework.aop.ThrowsAdvice
5.  引介通知 org.springframework.aop.IntroductionInterceptor

测试一下：

*  service层
    
        public class StudentServiceImpl implements StudentService {
              
            @Override
            public void learning() {
              
                System.out.println("正在学习");
            }
        }
 *  前置通知和后置通知类
    
        public class BeforeAdvice implements MethodBeforeAdvice {
              
            /**
             * @param method：目标对象的方法
             * @param objects：参数
             * @param o：目标对象
             */
           @Override
            public void before(Method method, Object[] objects, Object o) throws Throwable {
              
                System.out.println("前置通知执行了"+o.getClass().getName()+"的"+method.getName()+"方法");
            }
        }
    
        public class MyAfterLog2 implements AfterReturningAdvice {
              
        
            @Override
            public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {
              
                System.out.println("执行"+method.getName()+"方法后，返回结果为："+returnValue);
            }
        }
 *  xml配置
    
        <?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
                https://www.springframework.org/schema/beans/spring-beans.xsd
                http://www.springframework.org/schema/aop
                https://www.springframework.org/schema/aop/spring-aop.xsd">
        
           <bean id="studentService" class="com.yu.service.impl.StudentServiceImpl"/>
           <bean id="afterAdvice" class="com.yu.aopaip.AfterAdvice"/>
           <bean id="beforeAdvice" class="com.yu.aopaip.BeforeAdvice"/>
            
           <aop:config>
                
              <aop:pointcut id="point" expression="execution(* com.yu.service.impl.StudentServiceImpl.*(..))"/>
              <aop:advisor advice-ref="afterAdvice" pointcut-ref="point"/>
              <aop:advisor advice-ref="beforeAdvice" pointcut-ref="point"/>
        
           </aop:config>
        </beans>
 *  测试
    
        public class AppTest {
              
            @Test
            public void test(){
              
                ApplicationContext context = new ClassPathXmlApplicationContext("spring2.xml");
                StudentService service = (StudentService)context.getBean("studentService");
                service.learning();
            }
        }
    
    ![image-20220912193933401][]

##### 13.4.4、ProxyFactoryBean #####

ProxyFactoryBean是Spring环境中给指定的bean创建代理的一种方式，

*  service层
    
        public class StudentServiceImpl implements StudentService {
              
            @Override
            public void learning() {
              
                System.out.println("正在学习");
            }
        }
 *  XML方式
    
     *  前置通知和后置通知类
        
            public class AfterAdvice implements AfterReturningAdvice {
                    
            
                @Override
                public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable {
                    
                    System.out.println("后置通知执行"+method.getName()+"方法后，返回结果为："+o);
                }
            }
            public class BeforeAdvice implements MethodBeforeAdvice  {
                    
                @Override
                public void before(Method method, Object[] objects, Object o) throws Throwable {
                    
                    System.out.println("前置通知执行了"+o.getClass().getName()+"的"+method.getName()+"方法");
                }
            }
     *  xml配置
        
            <?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
                        https://www.springframework.org/schema/aop/spring-aop.xsd">
            
               <bean id="studentService" class="com.yu.service.impl.StudentServiceImpl"/>
               <bean id="afterAdvice" class="com.yu.aopaip.AfterAdvice"/>
               <bean id="beforeAdvice" class="com.yu.aopaip.BeforeAdvice"/>
               <bean id="proxyFactoryBean" class="org.springframework.aop.framework.ProxyFactoryBean">
                  <property name="target" ref="studentService"/>
                  <property name="interceptorNames">
                     <list>
                        <value>afterAdvice</value>
                        <value>beforeAdvice</value>
                     </list>
                  </property>
               </bean>
            </beans>
     *  获取proxyFactoryBean
        
            public class AppTest {
                    
                @Test
                public void test(){
                    
                    ApplicationContext context = new ClassPathXmlApplicationContext("spring2.xml");
                    StudentService service = (StudentService)context.getBean("proxyFactoryBean");
                    service.learning();
                }
            }
        
        ![image-20220912200645554][]
 *  注解
    
     *  在@Configuration中注册前置、后置通知，和proxyFactoryBean
        
            @Configuration
            @ComponentScan
            @EnableAspectJAutoProxy
            public class ExplainConfiguration {
                    
                @Bean
                public StudentService service(){
                    
                    return new StudentServiceImpl();
                }
                @Bean
                public MethodBeforeAdvice beforeAdvice() {
                    
                    return new MethodBeforeAdvice() {
                    
                        @Override
                        public void before(Method method, Object[] objects, Object o) throws Throwable {
                    
                            System.out.println("前置通知执行了"+o.getClass().getName()+"的"+method.getName()+"方法");
                        }
                    };
                }
                //注册一个后置通知
                @Bean
                public AfterReturningAdvice afterAdvice() {
                    
                    return new AfterReturningAdvice(){
                    
                        @Override
                        public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable {
                    
                            System.out.println("后置通知执行"+method.getName()+"方法后，返回结果为："+o);
                        }
                    };
                }
                //注册ProxyFactoryBean
                @Bean
                public ProxyFactoryBean service1Proxy() {
                    
                    //1.创建ProxyFactoryBean
                    ProxyFactoryBean proxyFactoryBean = new ProxyFactoryBean();
                    //2.设置目标对象的bean名称
                    proxyFactoryBean.setTarget(service());
                    //3.设置拦截器的bean名称列表，此处2个（advice1和advice2)
                    proxyFactoryBean.setInterceptorNames("beforeAdvice", "afterAdvice");
                    return proxyFactoryBean;
                }
            }
     *  获取ProxyFactoryBean测试
        
            public class AppTest {
                    
                @Test
                public void test(){
                    
                    ApplicationContext context = new AnnotationConfigApplicationContext(ExplainConfiguration.class);
                    StudentService service = (StudentService)context.getBean("service1Proxy");
                    service.learning();
                }
            }
        
        ![image-20220912201541663][]

[Java]: https://blog.csdn.net/yuandfeng/article/details/114333525
[image-20230330113659918]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/04/4eeaf9e13b664ff99ba9495538e2b597.png
[image-20230330114336341]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/04/55cd7db2d8674e92acb0d4e9baf8ef10.png
[image-20220912193933401]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/04/e0028474886c443dba19d324b982af38.png
[image-20220912200645554]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/04/82863b93a9764abbb6296db7bcd62e9d.png
[image-20220912201541663]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/04/200b1db98fc04d1eb2d923d65792d44a.png