Springaop 简明教程
Spring AOP - Proxy
到目前为止，我们已经使用 <aop:config> 或 < aop:aspectj-autoproxy> 声明了方面。我们可以以编程方式创建代理，也可以使用代理对象以编程方式调用方面。
Syntax
//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();其中，
-
AspectJProxyFactory − 创建代理对象的工厂类。
-
Logging.class − 包含建议的切面类。
-
Student − 待建议的目标业务类。
为了理解与代理相关的上述概念，我们来写一个将实施代理的示例。若要使用少量的建议来编写示例，我们先来设置一个可行的 Eclipse IDE，然后使用以下步骤来创建一个 Spring 应用程序：
Step |
Description |
1 |
更新在章节 Spring AOP - Application 创建的学生项目。 |
2 |
更新 bean 配置并按如下说明运行应用程序。 |
以下是 Logging.java 文件的内容。这实际上是方面模块的一个示例，它定义了在各个点调用的方法。
package com.tutorialspoint;
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.tutorialspoint.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("Going to setup student profile.");
}
}以下是 Student.java 文件的内容。
package com.tutorialspoint;
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.tutorialspoint;
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 。
<?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.tutorialspoint.Student">
<property name = "age" value = "11"/>
</bean>
<!-- Definition for logging aspect -->
<bean id = "logging" class = "com.tutorialspoint.Logging"/>
</beans>