@Around 是一种建议类型,可确保在方法执行之前和之后运行建议.以下是@Around建议的语法.
@PointCut("execution(* com) .it1352.Student.getAge(..))") private void selectGetName(){} @Around("selectGetAge()") public void aroundAdvice(ProceedingJoinPoint proceedingJoinPoint){ System.out.println("Around advice"); Object[] args = jp.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 = jp.proceed(args); System.out.println("Returning " + result); return result.toString(); }
其中,
@PointCut : 将函数标记为PointCut
执行(表达式) : 表达式涵盖了应用建议的方法.
@Around : 将函数标记为在PointCut涵盖的方法之前执行的建议.
要理解上述相关的概念@Around Advice,让我们编写一个实现@Around Advice的例子.要编写我们的示例并提供一些建议,让我们使用一个可用的Eclipse IDE并使用以下步骤创建一个Spring应用程序 :
Step | 描述 |
---|---|
1 | 更新项目学生根据章节 Spring AOP - 应用程序创建. |
2 | 更新bean配置并运行应用程序,如下所述. |
以下是 Logging.java 文件的内容.这实际上是方面模块的一个示例,它定义了在不同点调用的方法.
package com.it1352; 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.it1352.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.it1352; 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.it1352; 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 .
<?xml version = "1.0" encoding = "UTF-8"?> <beans xmlns = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/" xmlns:xsi = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/XMLSchema-instance" xmlns:aop = "https://img01.yuandaxia.cn/Content/img/tutorials/springaop/" xsi:schemaLocation = "http://www.springframework.org/schema/beans https://img01.yuandaxia.cn/Content/img/tutorials/springaop/spring-beans-3.0.xsd http://www.springframework.org/schema/aop https://img01.yuandaxia.cn/Content/img/tutorials/springaop/spring-aop-3.0.xsd "> <aop:aspectj-autoproxy/> <!-- Definition for student bean --> <bean id = "student" class = "com.IT屋.Student"> <property name = "name" value = "Zara" /> <property name = "age" value = "11"/> </bean> <!-- Definition for logging aspect --> <bean id = "logging" class = "com.IT屋.Logging"/> </beans>
完成源文件和配置文件的创建后,运行您的应用程序.右键单击应用程序中的MainApp.java,然后使用 run as Java Application 命令.如果你的申请一切正常,它将打印以下信息.
Around advice Age : 11 Returning 11