Spring AOP aop：提前运行后

Question

我最近在一个非常简单的应用程序上尝试了Spring的AOP功能，并且我坚持在适当的时间内运行该方法，这意味着本节中定义的方法应该在

在我的代码中，在中定义的方法都在main方法之前运行。 当然在后一种情况中是正常的，但在后一种情况中是不正常的。

预期输出应为：

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>

我的主班叫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

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()被称为System.out.println参数，因此之前先被调用，然后是trackCoach.getDailyWorkout（），然后被调用，最后是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";
    }
}

然后您会看到发生了什么。