引入增强-Spring AOP给目标bean添加新方法、功能

雨点打透心脏的1/2处 2022-11-27 12:08 158阅读 0赞

# 引入增强-Spring AOP给目标bean添加新方法、功能 #

**引入增强**：可以给已经存在的类增加方法、逻辑。  
我们以一个简单的Person类，只能run，给他增加一个fly的方法。

![在这里插入图片描述][20200815124822940.png_pic_center]

*  IPerson

public interface IPerson { 
        void run();
    }

*  Person

public class Person implements IPerson { 
        @Override
        public void run() { 
            System.out.println("可以跑...");
        }
    }

以上是一个很简单的接口、实现类，拥有一个run方法。

我们还拥有一个定义了fly的接口：

*  IFlying

public interface IFlying { 
        void fly();
    }

现在我们的目标是不修改IPerson、Person来让Person拥有fly的功能。这里可以使用Spring AOP的动态引入增强通知实现。

## 继承DelegatingIntroductionInterceptor ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3ppeGlhbzIxNw_size_16_color_FFFFFF_t_70_pic_center]  
**让FlyImpl扩展DelegatingIntroductionInterceptor 来实现**

*  FlyImpl

public class FlyImpl extends DelegatingIntroductionInterceptor implements IFlying { 
        @Override
        public void fly() { 
            System.out.println("我还会飞...");
        }
    }

## 配置代理 ##

*  application.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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd ">
    
    
    
        
        <bean id="person" class="org.byron4j.demo.Person"/>
    
        
        <bean id="fly" class="org.byron4j.demo.FlyImpl"/>
    
        
        <bean id="proxyBean" class="org.springframework.aop.framework.ProxyFactoryBean">
    
            
            <property name="interfaces" value="org.byron4j.demo.IFlying"/>
            
            <property name="interceptorNames" value="fly"/>
            
            <property name="target" ref="person"/>
            <property name="proxyTargetClass" value="true"/>
        </bean>
    
    </beans>

## pom.xml ##

<dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-aop</artifactId>
          <version>${spring.version}</version>
        </dependency>
    
        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context</artifactId>
          <version>${spring.version}</version>
        </dependency>
    
    
        <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>${junit.version}</version>
          <scope>compile</scope>
        </dependency>
    
    
        
        <dependency>
          <groupId>log4j</groupId>
          <artifactId>log4j</artifactId>
          <version>${log4j.version}</version>
        </dependency>
    
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-api</artifactId>
          <version>${slf4j.version}</version>
        </dependency>
    
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-log4j12</artifactId>
          <version>${slf4j.version}</version>
        </dependency>

## 测试 ##

@Test
        public void test(){ 
    
            ApplicationContext applicationContext
                    = new ClassPathXmlApplicationContext("application.xml");
    
            // 获得的是person
            IPerson person = ((IPerson) applicationContext.getBean("proxyBean"));
    
            IFlying flying = (IFlying) person;
    
            flying.fly();   // 输出：我还会飞...
    
    
        }

[20200815124822940.png_pic_center]: /images/20221124/d0764af6ed924ddbb1fbe0858546c43c.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3ppeGlhbzIxNw_size_16_color_FFFFFF_t_70_pic_center]: /images/20221124/11204660017b4741abed124cdbbde3f3.png