Spring AOP基於註解的Around通知
[@Around](https://github.com/Around "@Around")是一種建議類型，可確保方法執行前後的通知可以運行。 以下是[@Around](https://github.com/Around "@Around")通知的語法：
語法
@Pointcut("execution(* com.yiibai.Student.getAge(..))")
private void selectGetName(){}
@Around("selectGetAge()")
public void aroundAdvice(ProceedingJoinPoint proceedingJoinPoint){
System.out.println("[aroundAdvice] Around advice");
Object[] args=jp.getArgs();
if(args.length>0){
System.out.print("[aroundAdvice] Arguments passed: " );
for (int i = 0; i < args.length; i++) {
System.out.print("[aroundAdvice] arg "+(i+1)+": "+args[i]);
}
}
Object result=jp.proceed(args);
System.out.println("[aroundAdvice] Returning " + result);
return result.toString();
}在上面的語法示例中 -
-
[@Pointcut](https://github.com/Pointcut "@Pointcut")- 將函數標記爲切入點 -
execution( expression )- 涵蓋應用通知的方法的表達式。 -
[@Around](https://github.com/Around "@Around")- 將函數標記爲在切入點覆蓋的方法之前執行的通知。
要了解上面提到的[@Around](https://github.com/Around "@Around")通知相關的概念，我們寫一個Spring AOP基於註解的應用例子，它將使用基於註解配置實現通知。打開並使用Eclipse IDE，並按照以下步驟創建一個Spring應用程序：
- 更新在Spring AOP應用實例中創建過的
Student項目。 - 更新
bean配置並運行應用程序，如下所述。
整個項目的目錄結構如下所示 -
下面是Logging.java文件的內容。 這實際上是一個Aspect模塊的樣本，它定義了在各個點被調用的方法。
package com.yiibai;
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.yiibai.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文件的內容：
package com.yiibai;
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文件的內容：
package com.yiibai;
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文件的內容：
<?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 ">
<aop:aspectj-autoproxy/>
<!-- Definition for student bean -->
<bean id="student" class="com.yiibai.Student">
<property name="name" value="minsu" />
<property name="age" value="24"/>
</bean>
<!-- Definition for logging aspect -->
<bean id="logging" class="com.yiibai.Logging"/>
</beans>運行項目
完成創建源代碼和配置文件後，運行應用程序。右鍵單擊應用程序中的MainApp.java，並使用運行方式作爲Java應用程序命令。 如果您的應用程序一切正常，這將打印以下消息：
[aroundAdvice]Around advice
Age : 24
[aroundAdvice] Returning 24