Spring AOP代理
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小牛编辑
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2023-03-14
到目前为止,我们学习过如何使用<aop:config>
或<aop:aspectj-autoproxy>
声明方面。也可以通过编程方式创建代理,并使用代理对象以编程方式调用方面。
语法
//Create object to be proxied
Student student = new Student();
//Create the Proxy Factory
AspectJProxyFactory proxyFactory = new AspectJProxyFactory(student);
//Add Aspect class to the factory
proxyFactory.addAspect(Logging.class);
//Get the proxy object
Student proxyStudent = proxyFactory.getProxy();
//Invoke the proxied method.
proxyStudent.getAge();
在上面的语法示例中 -
AspectJProxyFactory
- 用于创建代理对象的工厂类。Logging.class
- 包含通知的方面类Student
- 将被通知的业务类。
要了解上面提到与代理相关的概念,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:
- 更新在Spring AOP应用实例中创建过的
Student
项目。 - 更新
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.yiibai;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.annotation.Before;
@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.yiibai.Student.getAge(..))")
private void selectGetAge(){}
/**
* This is the method which I would like to execute
* before a selected method execution.
*/
@Before("selectGetAge()")
public void beforeAdvice(){
System.out.println("[beforeAdvice] Going to setup student profile.");
}
}
以下是Student.java文件的内容:
package com.yiibai;
public class Student {
private Integer age;
public void setAge(Integer age) {
this.age = age;
}
public Integer getAge() {
System.out.println("Age : " + age );
return age;
}
}
以下是MainApp.java
文件的内容:
package com.yiibai;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.aop.aspectj.annotation.AspectJProxyFactory;
public class MainApp {
public static void main(String[] args) {
ApplicationContext context =
new ClassPathXmlApplicationContext("Beans.xml");
Student student = (Student) context.getBean("student");
//Create the Proxy Factory
AspectJProxyFactory proxyFactory = new AspectJProxyFactory(student);
//Add Aspect class to the factory
proxyFactory.addAspect(Logging.class);
//Get the proxy object
Student proxyStudent = proxyFactory.getProxy();
//Invoke the proxied method.
proxyStudent.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 ">
<!-- Definition for student bean -->
<bean id="student" class="com.yiibai.Student">
<property name="age" value="26"/>
</bean>
<!-- Definition for logging aspect -->
<bean id="logging" class="com.yiibai.Logging"/>
</beans>
运行项目
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:
[beforeAdvice] Going to setup student profile.
Age : 26