spring——AOP面向切面编程—— 一般切面的 AOP 开发

╰半夏微凉° 2024-03-31 17:34 105阅读 0赞

### 一般切面的 AOP 开发 ###

当我们在使用 Spring AOP 开发时，若没有对切面进行具体定义，Spring AOP 会通过 Advisor 为我们定义一个一般切面(不带切点的切面)，然后对目标对象(Target)中的所有方法连接点进行拦截，并织入增强代码。

#####  #####

工程依赖：

<?xml version="1.0" encoding="UTF-8"?>
    <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>org.example</groupId>
        <artifactId>ssw</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>5.3.6</version>
            </dependency>
        </dependencies>
    
    </project>

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userdao接口：

package org.example.dao;
    
    public interface UserDao
    {
    
        public void add();
    
        public void delete();
    
        public void modify();
    
        public void get();
    
    }

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实现userdao接口：

package org.example.dao.impl;
    
    import org.example.dao.UserDao;
    
    public class UserDaoImpl implements UserDao
    {
    
        @Override
        public void add() {
            System.out.println("正在执行 UserDao 的 add() 方法……");
        }
    
    
        @Override
        public void delete() {
            System.out.println("正在执行 UserDao 的 delete() 方法……");
        }
    
    
        @Override
        public void modify() {
            System.out.println("正在执行 UserDao 的 modify() 方法……");
        }
    
    
        @Override
        public void get() {
            System.out.println("正在执行 UserDao 的 get() 方法……");
        }
    
    }

![6bb30e13da1c78f7f562f0a17b4c7a8b.png][]

设置前置正确方法UserDaoBeforeAdvice：

package org.example.advice;
    
    import org.springframework.aop.MethodBeforeAdvice;
    import java.lang.reflect.Method;
    
    
    /**
     * 增强代码
     * MethodBeforeAdvice 前置增强
     *
     * @author c语言中文网 c.biancheng.net
     */
    
    
    public class UserDaoBeforeAdvice implements MethodBeforeAdvice
    {
    
        @Override
        public void before(Method method, Object[] args, Object target) throws Throwable
        {
    
            System.out.println("正在执行前置增强操作…………");
    
        }
    
    }

![faaa1dc79d4a58fbce5a0c491861a7e9.png][]

设置bean.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"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context.xsd">
    
        
    
        
        <bean id="userDao" class="org.example.dao.impl.UserDaoImpl"></bean>
    
    
        
        <bean id="beforeAdvice" class="org.example.advice.UserDaoBeforeAdvice"></bean>
    
    
        
        <bean id="userDaoProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
            
            <property name="target" ref="userDao"/>
            
            <property name="proxyInterfaces" value="org.example.dao.UserDao"/>
            
            <property name="interceptorNames" value="beforeAdvice"/>
        </bean>
    
    </beans>

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执行方法：

package org.example;
    
    import org.example.dao.UserDao;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class Main
    {
    
        public static void main(String[] args)
        {
            //获取 ApplicationContext 容器
            ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
    
            //获取代理对象
            UserDao userDao = context.getBean("userDaoProxy", UserDao.class);
    
            //调用 UserDao 中的各个方法
            userDao.add();
            userDao.delete();
            userDao.get();
            userDao.modify();
    
        }
    
    }

![170aec35845dac54782d6f235a57ec77.png][]

=======================================================================================

设置后置增强：

创建UserDaoAfterAdvice类：

package org.example.advice;
    
    import org.springframework.aop.AfterReturningAdvice;
    
    import java.lang.reflect.Method;
    
    public class UserDaoAfterAdvice implements AfterReturningAdvice
    {
    
        @Override
        public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable
        {
    
            System.out.println("正在执行后置增强操作…………");
        }
    }

![847ec1e1c749aa0c16096173548876b3.png][]

修改bean.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"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context.xsd">
    
        
    
        
        <bean id="userDao" class="org.example.dao.impl.UserDaoImpl"></bean>
    
    
        
        <bean id="beforeAdvice" class="org.example.advice.UserDaoBeforeAdvice"></bean>
        
        <bean id="afterAdvice" class="org.example.advice.UserDaoAfterAdvice"></bean>
    
    
        
        <bean id="userDaoProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
            
            <property name="target" ref="userDao"/>
            
            <property name="proxyInterfaces" value="org.example.dao.UserDao"/>
    
    
            
            <property name="interceptorNames" value="afterAdvice"/>
        </bean>
    
    </beans>

![0b6d6cf1a184adb27c1efe470bda6292.png][]

执行代码：

![20701dc7a65115a634c39a83f603df92.png][]

=======================================================================================

环绕增强：

创建UserDaoAroundAdvice类：

package org.example.advice;
    
    import org.aopalliance.intercept.MethodInterceptor;
    import org.aopalliance.intercept.MethodInvocation;
    
    public class UserDaoAroundAdvice implements MethodInterceptor
    {
    
    
        @Override
        public Object invoke(MethodInvocation methodInvocation) throws Throwable
        {
    
            System.out.println("基于Spring AOP的环绕增强前置处理.....");
            Object res = null;
    
            try
            {
                res=methodInvocation.proceed();//调用目标方法  返回目标方法的返回结果
            }
            catch (Throwable e)
            {
                e.printStackTrace();
            }
            System.out.println("基于Spring AOP的环绕增强后置处理.....");
            return res;
        }
    }

![13f70feb4cd6088f8bb0e7e5dc1ffb3f.png][]

修改bean.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"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
                http://www.springframework.org/schema/context/spring-context.xsd">
    
        
    
        
        <bean id="userDao" class="org.example.dao.impl.UserDaoImpl"></bean>
        
        
        <bean id="beforeAdvice" class="org.example.advice.UserDaoBeforeAdvice"></bean>
    
        
        <bean id="afterAdvice" class="org.example.advice.UserDaoAfterAdvice"></bean>
    
        
        <bean id="aroundAdvice" class="org.example.advice.UserDaoAroundAdvice"></bean>
    
    
        
        <bean id="userDaoProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
            
            <property name="target" ref="userDao"/>
            
            <property name="proxyInterfaces" value="org.example.dao.UserDao"/>
    
    
    
    
    
    
    
            
            <property name="interceptorNames" value="aroundAdvice"/>
        </bean>
    
    </beans>

![939ef7ea3a20619fdb859edd0648c8c9.png][]

![99b8f9032c30e2f6b95a1e545d8cabd3.png][]

执行代码：

![a6728026423d41bf2c82341e8e5acd95.png][]

=======================================================================================

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