根据PointCut表达式,可能会将它们应用于某些其他bean,而这些bean不是针对哪些建议的.例如,请考虑以下表达式.
execution(* com.it1352.*.getAge(..))
使用getAge()方法添加一个新的spring bean,虽然可能不是这样,但是建议将开始应用于它.为此,我们可以创建一个自定义注释并注释要应用建议的方法.
@Before("@annotation(com.it1352.Loggable)")
为了理解上述与@Before Advice相关的概念,让我们编写一个实现@的示例在建议之前.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 | 更新项目学生已创建在章节 Spring AOP - 应用程序. |
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.Before; @Aspect public class Logging { /** * This is the method which I would like to execute * before a selected method execution. */ @Before("@annotation(com.it1352.Loggable)") public void beforeAdvice(){ System.out.println("Going to setup student profile."); } }
以下是 Loggable.java 文件的内容 :
package com.it1352; public @interface Loggable { }
以下是学生的内容.java 文件.
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; } @Loggable 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.getName(); 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.it1352.Student"> <property name = "name" value = "Zara" /> <property name = "age" value = "11"/> </bean> <!-- Definition for logging aspect --> <bean id = "logging" class = "com.it1352.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.如果您的应用程序一切正常,它将打印以下消息.
Going to setup student profile. Name : Zara Age : 11