AOP（Aspect Oriented Programming壮不，面向切面編程）补箍，通過(guò)提供另一種思考程序的方式來(lái)補(bǔ)充OOP（Object Oriented Programming替裆，面向?qū)ο缶幊蹋┐朴纭OP是橫向抽取，OOP是縱向抽象臼婆。
切面可以用于事務(wù)管理抒痒、日志等方面的模塊化
AOP核心概念
- Aspect（切面）
- Join Point（連接點(diǎn)）
- Advice（通知/增強(qiáng)）
- Pointcut（切點(diǎn)）
- Introduction（引入）
- Target Object（目標(biāo)對(duì)象）
- AOP Proxy（AOP代理）
- Weaving（織入）
其中，Advice的主要類(lèi)型有:
- Before Advice（前置通知）
- After Returning Advice(返回后通知）
- After Throwing Advice（拋出異常后通知）
- After （finally）Advice（最后通知）
- Around Advice（環(huán)繞通知）
切入點(diǎn)和連接點(diǎn)的匹配颁褂，是AOP的關(guān)鍵
Spring AOP
Spring AOP用純Java實(shí)現(xiàn)故响，目前僅支持方法調(diào)用作為連接點(diǎn)。
Spring AOP通常和Spring IoC容器一起使用
Hello的前置增強(qiáng)練習(xí)
- pom.xml中添加AOP相關(guān)依賴
<?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>
<!--spring-context依賴-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<!--spring-aop依賴-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<!--aspectj依賴-->
<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依賴-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!--junit依賴-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<!-- log4j日志依賴 -->
<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>
</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接口和實(shí)現(xiàn)類(lèi)
package com.spring.aop;
public interface Hello {
String sayHello();
}
package com.spring.aop;
public class HelloImpl implements Hello {
@Override
public String sayHello() {
return "Spring AOP";
}
}
- MyBefore類(lèi)
package com.spring.aop;
/**
* 用戶自定義前置增強(qiáng)類(lèi)
*/
public class MyBefore {
public void beforeMethod() {
System.out.println("This is a before method...");
}
}
- 配置文件
<bean id="hello" class="com.spring.aop.HelloImpl"/>
<bean id="myBefore" class="com.spring.aop.MyBefore"/>
<aop:config>
<aop:aspect id="before" ref="myBefore">
<aop:pointcut id="myPointcut" expression="execution(* com.spring.aop.*.*(..))"/>
<aop:before method="beforeMethod" pointcut-ref="myPointcut"/>
</aop:aspect>
</aop:config>
- 應(yīng)用主類(lèi)
package com.spring.aop;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class HelloApp {
public static void main(String[] args) {
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
Hello hello = (Hello) ac.getBean("hello");
System.out.println(hello.sayHello());
}
}
-
運(yùn)行結(jié)果
運(yùn)行結(jié)果
可以看到：Mybefore的方法被織入到了Hello的調(diào)用方法前面颁独，前置增強(qiáng)生效
實(shí)戰(zhàn)：使用@AspectJ注解的例子
“武松打虎”——武松（Fighter）在山里等著老虎（Tiger）出現(xiàn)彩届，只要發(fā)現(xiàn)老虎出來(lái)，就打老虎誓酒。
- 定義業(yè)務(wù)模型
Tiger類(lèi)
package com.spring.aspectj;
public class Tiger {
public void walk() {
System.out.println("Tiger is walking...");
}
}
- 定義切面和配置
前置通知和后置通知
Fighter類(lèi)
package com.spring.aspectj;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
@Aspect
public class Fighter {
@Pointcut("execution(* com.spring.aspectj.Tiger.walk())")
public void foundTiger() {
}
@Before(value = "foundTiger()")
public void foundBefore() {
System.out.println("Fighter wait for tiger...");
}
@AfterReturning("foundTiger()")
public void foundAfter() {
System.out.println("Fighter fight with tiger...");
}
}
- 配置文件
<!--啟動(dòng)AspectJ支持-->
<aop:aspectj-autoproxy/>
<!--配置bean-->
<bean id="tiger" class="com.spring.aspectj.Tiger"/>
<bean id="fighter" class="com.spring.aspectj.Fighter"/>
- 主程序
package com.spring.aspectj;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class FighterApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
Tiger tiger = context.getBean(Tiger.class);
tiger.walk();
}
}
-
運(yùn)行結(jié)果
運(yùn)行結(jié)果
