Spring AOP aop：提前運行后

Question

我最近在一個非常簡單的應用程序上嘗試了Spring的AOP功能，並且我堅持在適當的時間內運行該方法，這意味着本節中定義的方法應該在

在我的代碼中，在中定義的方法都在main方法之前運行。 當然在后一種情況中是正常的，但在后一種情況中是不正常的。

預期輸出應為：

HERE IS THE AOP BEFORE

From App ran 5k

HERE IS THE AOP After

我當前的輸出是：

HERE IS THE AOP BEFORE

HERE IS THE AOP After

From App ran 5k

知道為什么嗎？

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");
}

}

教練

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

那是因為trackCoach.getDailyWorkout()被稱為System.out.println參數，因此之前先被調用，然后是trackCoach.getDailyWorkout（），然后被調用，最后是System.out。 嘗試例如：

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

然后您會看到發生了什么。