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Spring初学之annotation实现AOP前置通知和后置通知
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实现两个整数的加减乘除，并在每个计算前后打印出日志。
ArithmeticCalculator.java：
package spring.aop.impl;public interface ArithmeticCalculator { int add(int i,int j);
int sub(int i,int j);
int mul(int i,int j);
int div(int i,int j);}
ArithmeticCalculatorImpl.java：
package spring.aop.impl;import org.springframework.stereotype.Component;@Component("arithmeticCalculator")
public class ArithmeticCalculatorImpl implements ArithmeticCalculator { public int add(int i, int j) {
int result = i+j;
return result;
} public int sub(int i, int j) {
int result = i-j;
return result;
} public int mul(int i, int j) {
int result = i*j;
return result;
} public int div(int i, int j) {
int result = i/j;
return result;
}}
LoggingAspect.java：
package spring.aop.impl;import java.util.Arrays;
import java.util.List;import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;//把这个类声明为一个切面：1.把该类放入到IOC容器中，2.再声明一个切面@Aspect
@Component
public class LoggingAspect { //声明该方法是一个前置通知：在目标方法之前执行
@Before("execution( public int spring.aop.impl.*.*(int,int) )")
public void beforeMethod(JoinPoint joinPoint){
String methodName=joinPoint.getSignature().getName();
List<Object> args=Arrays.asList(joinPoint.getArgs());
System.out.println("The method "+methodName+" begins"+args);
} //后置通知：在目标方法执行后执行（无论是否发生异常），的通知。
//在后置通知中不能访问目标方法的执行结果
@After("execution( public int spring.aop.impl.*.*(int,int) )")
public void afterMethod(JoinPoint joinPoint){
String methodName=joinPoint.getSignature().getName();
System.out.println("The method "+methodName+" ends");
}}
ApplicationContext.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:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"> <!-- 配置自动扫描的包 -->
<context:component-scan base-package="spring.aop.impl" /> <!-- 使AspectJ注解起作用，自动为匹配的类生成代理对象 -->
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
</beans>
测试：
package spring.aop.impl.test;import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;import spring.aop.impl.ArithmeticCalculator;public class Main {
public static void main(String[] args) { //1.创建spring的IOC容器
ApplicationContext ctx=new ClassPathXmlApplicationContext("applicationContext.xml");
//2.从容器中获取bean的实例
ArithmeticCalculator arithmeticCalculator=(ArithmeticCalculator) ctx.getBean("arithmeticCalculator");
//3.使用bean
int result = arithmeticCalculator.add(5, 8);
System.out.println("result:"+result); result = arithmeticCalculator.div(5, 8);
System.out.println("result:"+result);
}
}
输出：
The method add begins[5, 8]
The method add ends
result:13
The method div begins[5, 8]
The method div ends
result:0
