@Around
是一种建议类型,可确保方法执行前后的通知可以运行。 以下是@Around
通知的语法:
语法
@Pointcut("execution(* com.zyiz.Student.getAge(..))") private void selectGetName(){} @Around("selectGetAge()") public void aroundAdvice(ProceedingJoinPoint proceedingJoinPoint){ System.out.println("[aroundAdvice] Around advice"); Object[] args=jp.getArgs(); if(args.length>0){ System.out.print("[aroundAdvice] Arguments passed: " ); for (int i = 0; i < args.length; i++) { System.out.print("[aroundAdvice] arg "+(i+1)+": "+args[i]); } } Object result=jp.proceed(args); System.out.println("[aroundAdvice] Returning " + result); return result.toString(); }
在上面的语法示例中 -
要了解上面提到的@Around
通知相关的概念,我们写一个Spring AOP基于注解的应用例子,它将使用基于注解配置实现通知。打开并使用Eclipse IDE,并按照以下步骤创建一个Spring应用程序:
Student
项目。bean
配置并运行应用程序,如下所述。整个项目的目录结构如下所示 -
下面是Logging.java
文件的内容。 这实际上是一个Aspect
模块的样本,它定义了在各个点被调用的方法。
package com.zyiz; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.ProceedingJoinPoint; @Aspect public class Logging { /** Following is the definition for a pointcut to select * all the methods available. So advice will be called * for all the methods. */ @Pointcut("execution(* com.zyiz.Student.getAge(..))") private void selectGetAge(){} /** * This is the method which I would like to execute * around a selected method execution. */ @Around("selectGetAge()") public void aroundAdvice(ProceedingJoinPoint proceedingJoinPoint) throws Throwable{ System.out.println("Around advice"); Object[] args=proceedingJoinPoint.getArgs(); if(args.length>0){ System.out.print("Arguments passed: " ); for (int i = 0; i < args.length; i++) { System.out.print("arg "+(i+1)+": "+args[i]); } } Object result=proceedingJoinPoint.proceed(args); System.out.println("Returning " + result); } }
以下是Student.java文件的内容:
package com.zyiz; public class Student { private Integer age; private String name; public void setAge(Integer age) { this.age = age; } public Integer getAge() { System.out.println("Age : " + age ); return age; } public void setName(String name) { this.name = name; } public String getName() { System.out.println("Name : " + name ); return name; } public void printThrowException(){ System.out.println("Exception raised"); throw new IllegalArgumentException(); } }
以下是MainApp.java
文件的内容:
package com.zyiz; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainApp { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml"); Student student = (Student) context.getBean("student"); student.getAge(); } }
以下是配置文件Beans.xml文件的内容:
<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd "> <aop:aspectj-autoproxy/> <!-- Definition for student bean --> <bean id="student" class="com.zyiz.Student"> <property name="name" value="minsu" /> <property name="age" value="24"/> </bean> <!-- Definition for logging aspect --> <bean id="logging" class="com.zyiz.Logging"/> </beans>
完成创建源代码和配置文件后,运行应用程序。右键单击应用程序中的MainApp.java
,并使用运行方式作为Java应用程序命令。 如果您的应用程序一切正常,这将打印以下消息:
[aroundAdvice]Around advice Age : 24 [aroundAdvice] Returning 24