java - Spring AOP aop :after running early

Question

我最近一直在一个非常简单的应用程序上尝试 Spring 的 AOP 功能，并且我坚持在适当的时间运行该方法，这意味着该部分中定义的方法应该在

中定义的方法之后运行

在我的代码中，这两个方法都在主方法中定义并在主方法之前运行。当然，在后者中这是正常的，但在后者中则不然。

预期输出应该是:

HERE IS THE AOP BEFORE

From App ran 5k

HERE IS THE AOP After

我当前的输出是:

HERE IS THE AOP BEFORE

HERE IS THE AOP After

From App ran 5k

知道为什么吗？

Pom.xml:

<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>springDemo</groupId>
<artifactId>FirstSpringDemo</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>FirstSpringDemo</name>
<url>http://maven.apache.org</url>
<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>
<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>4.3.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.3.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>4.3.1.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>3.8.1</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <dependency>
        <groupId>cglib</groupId>
        <artifactId>cglib</artifactId>
        <version>2.2</version>
    </dependency>
    <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjweaver</artifactId>
        <version>1.6.11</version>
    </dependency>
</dependencies>
</project>

我的主类，称为 App:

package main.java.springDemo;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {
public static void main(String[] args) {

    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

    Coach trackCoach = context.getBean("myTrackCoach", Coach.class);

    System.out.println(" From App " + trackCoach.getDailyWorkout());


}
}

TrackerCoach.java

package main.java.springDemo;

public class TrackCoach implements Coach {
@Override
public String getDailyWorkout() {
    return "Go and run 5k";
}
}

SayAOP.java

package main.java.springDemo;


public class SayAOP {

   public void shoutAOPBefore() {

    System.out.println("HERE IS THE AOP BEFORE");
}

public void shoutAOPAfter(){

    System.out.println("HERE IS THE AOP After");
}

}

教练.java

package main.java.springDemo;

public interface Coach {
    String getDailyWorkout();

}

applicationContext.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"
   xmlns:aop="http://www.springframework.org/schema/aop"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

<!-- Define your beans here -->


<aop:config>

    <aop:aspect id="aop" ref="SayAOP">

        <aop:pointcut id="pid" expression="execution(* main.java.springDemo.Coach.getDailyWorkout(..))"/>

        <aop:before pointcut-ref="pid" method="shoutAOPBefore"/>
        <aop:after pointcut-ref="pid" method="shoutAOPAfter"/>
    </aop:aspect>

</aop:config>

<bean id="myTrackCoach"
      class="main.java.springDemo.TrackCoach">

</bean>

<bean id="SayAOP"
      class="main.java.springDemo.SayAOP">
</bean>

</beans>

Answer 1

那是因为trackCoach.getDailyWorkout()作为 System.out.println 参数调用，因此首先调用 before，然后调用 trackCoach.getDailyWorkout()，然后调用 after，最后调用 System.out。尝试例如:

public class TrackCoach implements Coach {
    @Override
    public String getDailyWorkout() {
        System.out.println("Go and run 5k");
        return "Go and run 5k";
    }
}

你会看到会发生什么。