Springaop 简明教程
Spring AOP - Annotation Based Around Advice
@Around 是建议类型，它确保建议可以在方法执行前后运行。以下是 @Around 建议的语法：
Syntax
@Pointcut("execution(* com.tutorialspoint.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 − 将函数标记为切入点
-
execution( expression ) − 涵盖应用建议的方法的表达式。
-
@Around − 将方法标记为在切入点涵盖的方法之前执行的建议。
为了理解与 @Around 相关建议已经提到的概念，我们来写一个将实施 @Around 建议的示例。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.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.tutorialspoint.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.tutorialspoint;
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.tutorialspoint;
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 = "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.tutorialspoint.Student">
<property name = "name" value = "Zara" />
<property name = "age" value = "11"/>
</bean>
<!-- Definition for logging aspect -->
<bean id = "logging" class = "com.tutorialspoint.Logging"/>
</beans>