Spring Aop

AOP(Aspect Oriented Programming,面向切面编程)通过提供另一种思考程序结构的方式来补充OOP(Object Oriented Programming,面向对象编程）。OOP模块化的关键单元是类，而在AOP中，模块化的单元是切面（Aspect）。切面可以实现跨多个类型和对象之间的事务管理、日志等方面的模块化。
OOP用继承和组合的方式，编制成一套类和对象的体系；而AOP凡某包某类某命名方法，一并同样处理（正则表达式）。

AOP核心概念

1：Aspect（切面）
2：Join Point(连接点）
3：Advice（通知/增强）
4：Pointcut：（切入点）
5：Introduction（引入）
6：Target Object（目标对象）
7：AOP Proxy（AOP代理）
8：Weaving(织入）

其中Advice的类型：

1.Before Adivce(前置通知）
2.After Returning Advice(返回后通知）
3.After Throwing Advice(抛出异常后通知）
4.After(finally)Advice(最后通知)
5.Around Advice(环绕通知）

前置增强：

pom.xml中添加依赖

<?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>com.spring</groupId>
  <artifactId>AoP</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>AoP</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <spring.version>5.1.5.RELEASE</spring.version>
    <aspectj.version>1.9.2</aspectj.version>
    <junit.version>4.12</junit.version>
    <log4j.version>1.2.17</log4j.version>
    <slf4j.version>1.7.12</slf4j.version>
  </properties>

  <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>${spring.version}</version>
    </dependency>
    <!--spring-aop依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <!--aspectj依赖-->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjrt</artifactId>
      <version>${aspectj.version}</version>
    </dependency>
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>${aspectj.version}</version>
    </dependency>
    <!--spring-test依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>${junit.version}</version>
      <scope>test</scope>
    </dependency>
    <!--Lombok依赖-->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.16.18</version>
    </dependency>
    <!-- log4j日志依赖 -->
    <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>
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>${log4j.version}</version>
    </dependency>


  </dependencies>

  <build>
    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
      <plugins>
        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
        <plugin>
          <artifactId>maven-clean-plugin</artifactId>
          <version>3.1.0</version>
        </plugin>
        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
        <plugin>
          <artifactId>maven-resources-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.0</version>
        </plugin>
        <plugin>
          <artifactId>maven-surefire-plugin</artifactId>
          <version>2.22.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-jar-plugin</artifactId>
          <version>3.0.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-install-plugin</artifactId>
          <version>2.5.2</version>
        </plugin>
        <plugin>
          <artifactId>maven-deploy-plugin</artifactId>
          <version>2.8.2</version>
        </plugin>
        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
        <plugin>
          <artifactId>maven-site-plugin</artifactId>
          <version>3.7.1</version>
        </plugin>
        <plugin>
          <artifactId>maven-project-info-reports-plugin</artifactId>
          <version>3.0.0</version>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

hello实例代码：
Hello接口：

package com.spring.Aop;

/**
 * Created by User on 2019/3/7.
 */
public interface Hello {
    String getHello();
}

实现类：

package com.spring.Aop;

/**
 * Created by User on 2019/3/7.
 */
public class HelloImpl implements Hello{
    @Override
    public String getHello() {
        return "Hello,Spring Aop";
    }
}

MyBeforeAdvice:

package com.spring.Aop;
/**
 * Created by User on 2019/3/7.
 * 用户自定义的前置增强类
 */
public class MyBeforeAdvice {
//    定义前置方法
    public void beforeMethod(){
          System.out.println("This is a before method.");
    }

}

配置文件：

 <!--配置一个Hello的bean,等同于Hello hello=new HelloImpl();-->
    <bean id="hello" class="com.spring.Aop.HelloImpl"/>
    <!--配置一个MyBeforeAdvice前置增强的bean-->
    <bean id="myBeforeAdvice" class="com.spring.Aop.MyBeforeAdvice"/>
    <!--配置aop-->
    <aop:config>
        <aop:aspect id="before" ref="myBeforeAdvice">
            <aop:pointcut id="myPointCut" expression="execution(* com.spring.Aop.*.*(..))"/>
            <aop:before method="beforeMethod" pointcut-ref="myPointCut"/>
        </aop:aspect>
    </aop:config>

HelloApp:

package com.spring.Aop;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Created by User on 2019/3/7.
 */
public class HelloAPP {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("Spring.xml");
        Hello hello=context.getBean(Hello.class);
        System.out.println(hello.getHello());
    }

}

结果.png