Spring AOP核心功能示例代码详解

Spring AOP核心功能 Spring AOP核心技术 2023-02-28 11:02:17 666人浏览安东尼

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摘要

目录前言背景ProxyFactoryAdvicePointcutAdvisorspring提供的代理支持ProxyFactoryBeanDefaultPointcutAdvisor优

前言

spring一直以来都是我们Java开发中最核心的一个技术，其中又以ioc和aop为主要技术，本篇文章主要讲一下aop的核心技术，也就是ProxyFactory技术的使用，而基本的jdk动态代理和cglib代理技术并不涉及，如有需要，请自行寻找资料

背景

package com.zxc.boot.proxy;
public class OrderService {
    public void create() {
        System.out.println("创建订单");
    }
    public void payOrder() {
        System.out.println("支付订单");
    }
}

假设你有如上的对象，需要对两个方法前面都插入生成订单号的逻辑，如果是传统的方式就可以直接加入，但是过于麻烦，如果使用spring的话，就可以借助如下的工具类，如

ProxyFactory

package com.zxc.boot.proxy;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.ProxyFactory;
import java.lang.reflect.Method;
public class Main {
    public static void main(String[] args) {
        //被代理对象
        OrderService orderService = new OrderService();
        ProxyFactory proxyFactory = new ProxyFactory();
        //设置代理对象
        proxyFactory.setTarget(orderService);
        //添加代理逻辑
        proxyFactory.addAdvice(new MethodBeforeAdvice() {
            @Override
            public void before(Method method, Object[] objects, Object o) throws Throwable {
                System.out.println("-----生成订单号------");
            }
        });
        //获取代理对象
        OrderService orderServiceProxy = (OrderService) proxyFactory.getProxy();
        orderServiceProxy.create();
        orderServiceProxy.payOrder();
    }
}

生成的结果如下(注：这里没有接口，肯定是使用cglib生成的代理对象)

是不是很简单呢，底层逻辑都是spring帮我们实现的，而MethodBeforeAdvice就是进行的代理逻辑，它的父接口是

Advice

这个简单理解就是对象被代理的逻辑，主要有以下的实现，如

MethodBeforeAdvice、AfterReturningAdvice、MethodInterceptor等等见名思义

但是这里有一个问题，我们两个方法都被进行了代理，那么是否有办法实现只代理某个方法，而某些方法不进行代理呢，答案是有的，代码如下

package com.zxc.boot.proxy;
import org.aopalliance.aop.Advice;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.Pointcut;
import org.springframework.aop.PointcutAdvisor;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.aop.support.StaticMethodMatcherPointcut;
import java.lang.reflect.Method;
public class Main2 {
    public static void main(String[] args) {
        //被代理对象
        OrderService orderService = new OrderService();
        ProxyFactory proxyFactory = new ProxyFactory();
        //设置代理对象
        proxyFactory.setTarget(orderService);
        //添加代理逻辑
        proxyFactory.addAdvisor(new PointcutAdvisor() {
            @Override
            public Pointcut getPointcut() {
                //哪些方法进行代理
                return new StaticMethodMatcherPointcut() {
                    @Override
                    public boolean matches(Method method, Class<?> aClass) {
                        //方法名为create进行代理
                        return method.getName().equals("create");
                    }
                };
            }
            //代理逻辑
            @Override
            public Advice getAdvice() {
                return new MethodBeforeAdvice() {
                    @Override
                    public void before(Method method, Object[] objects, Object o) throws Throwable {
                        System.out.println("-----创建订单-----");
                    }
                };
            }
            @Override
            public boolean isPerInstance() {
                return false;
            }
        });
        //获取代理对象
        OrderService orderServiceProxy = (OrderService) proxyFactory.getProxy();
        orderServiceProxy.create();
        orderServiceProxy.payOrder();
    }
}

可以看到，只有创建订单的方法才会添加代理逻辑，而支付订单并不会加入这段逻辑，而核心的功能点就是依赖于Pointcut对象

Pointcut

Pointcut简单理解就是切掉，也就是用于判断要在哪些方法或者哪些类注入代理逻辑用的

Advisor

而Advisor简单理解就是Advice和Pointcut的组合，spring当中进行代理的逻辑也是用Advisor为维度进行处理的

以上，就是使用ProxyFactory进行代理逻辑的spring工具类，但是很明显这样使用相对来说还是比较麻烦的，所以spring提供了简易的方式让我们使用这种逻辑，如下

Spring提供的代理支持

ProxyFactoryBean

package com.zxc.boot.proxy;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.ProxyFactoryBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import java.lang.reflect.Method;
@Configuration
@ComponentScan("com.zxc.boot.proxy")
public class AppConfig {
    @Bean
    public ProxyFactoryBean proxyFactoryBean() {
        ProxyFactoryBean proxyFactoryBean = new ProxyFactoryBean();
        proxyFactoryBean.setTarget(new OrderService());
        proxyFactoryBean.addAdvice(new MethodBeforeAdvice() {
            @Override
            public void before(Method method, Object[] objects, Object o) throws Throwable {
                System.out.println("-------创建订单-------");
            }
        });
        return proxyFactoryBean;
    }
}

package com.zxc.boot.proxy;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class SpringApplication {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);
        OrderService orderService = applicationContext.getBean(OrderService.class);
        orderService.create();
        orderService.payOrder();
    }
}

只要进行如上的配置，就可以识别到了，这种方式其实跟原有的差不多，只不过spring帮我们处理了最终会返回对应的代理bean回去，但是还有更简单的方式，如下

DefaultPointcutAdvisor

package com.zxc.boot.proxy;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.aop.support.NameMatchMethodPointcut;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import java.lang.reflect.Method;
@Configuration
@ComponentScan("com.zxc.boot.proxy")
public class AppConfig2 {
    @Bean
    public OrderService orderService() {
        return new OrderService();
    }
    @Bean
    public DefaultPointcutAdvisor defaultPointcutAdvisor() {
        //方法名称蓝机器
        NameMatchMethodPointcut nameMatchMethodPointcut = new NameMatchMethodPointcut();
        nameMatchMethodPointcut.addMethodName("create");
        //设置拦截和代理逻辑
        DefaultPointcutAdvisor defaultPointcutAdvisor = new DefaultPointcutAdvisor();
        defaultPointcutAdvisor.setPointcut(nameMatchMethodPointcut);
        defaultPointcutAdvisor.setAdvice(new MethodBeforeAdvice() {
            @Override
            public void before(Method method, Object[] args, Object target) throws Throwable {
                System.out.println("-------创建订单------");
            }
        });
        return defaultPointcutAdvisor;
    }
    //核心类，一个BeanPostProccess后置处理器，用于把扫描到的Advisor进行代理
    @Bean
    public DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator() {
        return new DefaultAdvisorAutoProxyCreator();
    }
}

package com.zxc.boot.proxy;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class SpringApplication {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig2.class);
        OrderService orderService = applicationContext.getBean(OrderService.class);
        orderService.create();
        orderService.payOrder();
    }
}

不用我们多做其他处理，就可以对ioc容器中方法有create的类进行代理，你可以再添加一个类，如下

package com.zxc.boot.proxy;
public class UserService {
    public void create() {
        System.out.println("用户service哦哦哦");
    }
}

package com.zxc.boot.proxy;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class SpringApplication {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig2.class);
        OrderService orderService = applicationContext.getBean(OrderService.class);
        orderService.create();
        orderService.payOrder();
        UserService userService = applicationContext.getBean(UserService.class);
        userService.create();
    }
}

这样的方式就方便多了

优化处理

其实DefaultAdvisorAutoProxyCreator只是需要导入到ioc容器中，所以配置类可以使用import进行处理，效果是一样的，如下

package com.zxc.boot.proxy;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.aop.support.NameMatchMethodPointcut;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import java.lang.reflect.Method;
@Configuration
@ComponentScan("com.zxc.boot.proxy")
@Import(DefaultAdvisorAutoProxyCreator.class)
public class AppConfig2 {
    @Bean
    public UserService userService() {
        return new UserService();
    }
    @Bean
    public OrderService orderService() {
        return new OrderSepackage com.zxc.boot.proxy;
import org.springframework.aop.MethodBeforeAdvice;
import org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.aop.support.NameMatchMethodPointcut;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import java.lang.reflect.Method;
@Configuration
@ComponentScan("com.zxc.boot.proxy")
@Import(DefaultAdvisorAutoProxyCreator.class)
public class AppConfig2 {
    @Bean
    public UserService userService() {
        return new UserService();
    }
    @Bean
    public OrderService orderService() {
        return new OrderService();
    }
    @Bean
    public DefaultPointcutAdvisor defaultPointcutAdvisor() {
        //方法名称蓝机器
        NameMatchMethodPointcut nameMatchMethodPointcut = new NameMatchMethodPointcut();
        nameMatchMethodPointcut.addMethodName("create");
        //设置拦截和代理逻辑
        DefaultPointcutAdvisor defaultPointcutAdvisor = new DefaultPointcutAdvisor();
        defaultPointcutAdvisor.setPointcut(nameMatchMethodPointcut);
        defaultPointcutAdvisor.setAdvice(new MethodBeforeAdvice() {
            @Override
            public void before(Method method, Object[] args, Object target) throws Throwable {
                System.out.println("-------创建订单------");
            }
        });
        return defaultPointcutAdvisor;
    }
//    //核心类，一个BeanPostProccess后置处理器，用于把扫描到的Advisor进行代理
//    @Bean
//    public DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator() {
//        return new DefaultAdvisorAutoProxyCreator();
//    }
}rvice();
    }
    @Bean
    public DefaultPointcutAdvisor defaultPointcutAdvisor() {
        //方法名称蓝机器
        NameMatchMethodPointcut nameMatchMethodPointcut = new NameMatchMethodPointcut();
        nameMatchMethodPointcut.addMethodName("create");
        //设置拦截和代理逻辑
        DefaultPointcutAdvisor defaultPointcutAdvisor = new DefaultPointcutAdvisor();
        defaultPointcutAdvisor.setPointcut(nameMatchMethodPointcut);
        defaultPointcutAdvisor.setAdvice(new MethodBeforeAdvice() {
            @Override
            public void before(Method method, Object[] args, Object target) throws Throwable {
                System.out.println("-------创建订单------");
            }
        });
        return defaultPointcutAdvisor;
    }
//    //核心类，一个BeanPostProccess后置处理器，用于把扫描到的Advisor进行代理
//    @Bean
//    public DefaultAdvisorAutoProxyCreator defaultAdvisorAutoProxyCreator() {
//        return new DefaultAdvisorAutoProxyCreator();
//    }
}

如果你不导入DefaultAdvisorAutoProxyCreator对象，那么代理逻辑就不会生效，本质就是DefaultAdvisorAutoProxyCreator类就是一个BeanPostProcessor处理器，它会针对所有类进行判断然后处理