21Spring重用切点表达式
2024-08-23 20:28:25
直接看代码：
package com.cn.spring.aop.impl;
//加减乘除的接口类
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);
}
package com.cn.spring.aop.impl; import org.springframework.stereotype.Component; //实现类
@Component
public class ArithmeticCalculatorImpl implements ArithmeticCalculator {
@Override
public int add(int i, int j) {
int result = i + j;
return result;
} @Override
public int sub(int i, int j) {
int result = i - j;
return result;
} @Override
public int mul(int i, int j) {
int result = i * j;
return result;
} @Override
public int div(int i, int j) {
int result = i / j;
return result;
}
}
package com.cn.spring.aop.impl; import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component; import java.util.Arrays;
import java.util.List; //把这个类声明为一个切面：首先需要把该类放入到IOC容器中，在声明为一个切面
//可以使用@order注解指定切面的优先级，值越小，优先级越高
@Order(2)
@Aspect
@Component
public class LoggingAspect { /**
* 定义一个方法，用于声明切入点表达式，一般的，该方法中再不需要添入其他的代码
* 使用@Pointcut来声明切入点表达式
* 后面的其他通知直接使用方法名来引用当前的切入点表达式
*/
@Pointcut(value = "execution(public int ArithmeticCalculator.*(..))")
public void declareJoinPointExpression() {} //声明该方法是一个前置通知：在目标方法开始之前执行
@Before("declareJoinPointExpression()")
public void beforeMethod(JoinPoint joinPoint) {
String methodName = joinPoint.getSignature().getName();
List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method " + methodName + " begins with " + args);
} //后置通知：在目标方法执行后（无论是否发生异常），执行的通知
//在后置通知中还不能访问目标方法执行的结果
@After("declareJoinPointExpression()")
public void afterMethod(JoinPoint joinPoint) {
String methodName = joinPoint.getSignature().getName();
List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method " + methodName + " ends with " + args);
} /**
* 在方法正常结束后执行的代码
* 返回通知是可以访问到方法的返回值
* @param joinPoint
*/
@AfterReturning(value = "declareJoinPointExpression()",
returning = "result")
public void afterReturning(JoinPoint joinPoint, Object result) {
String methodName = joinPoint.getSignature().getName();
List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method ends witd " + result);
} //在目标方法出现异常时会执行的代码
//可以访问到异常对象；且可以指定在出现特定异常时再执行通知代码
@AfterThrowing(value = "declareJoinPointExpression()",
throwing = "ex")
public void afterReturning(JoinPoint joinPoint, Exception ex) {
String methodName = joinPoint.getSignature().getName(); System.out.println("The method " + methodName + " occures exception with: " + ex);
} /**
* 环绕通知需要携带ProceedingJoinPoint类型的参数
* 环绕通知类似于动态代理的全过程：ProceedingJoinPoint类型的参数可以决定是否执行目标方法
* 且环绕通知必须有返回值，返回值为目标方法的返回值
* @param proceedingJoinPoint
*/
@Around("declareJoinPointExpression()")
public Object aroundMethod(ProceedingJoinPoint proceedingJoinPoint) {
Object result = null;
String methodName = proceedingJoinPoint.getSignature().getName();
//执行目标方法
try {
//前置通知
System.out.println("The method " + methodName + " begins with " + Arrays.asList(proceedingJoinPoint.getArgs()));
result = proceedingJoinPoint.proceed();
//返回通知
System.out.println("The method ends with " + result);
} catch (Throwable throwable) {
//异常通知
System.out.println("The method " + methodName + " occures exception with: " + throwable);
throw new RuntimeException(throwable);
}
//后置通知
System.out.println("The method " + methodName + " ends");
return result;
}
}
package com.cn.spring.aop.impl; import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component; import java.util.Arrays; @Order(1)
@Aspect
@Component
public class ValidationAspect { @Before("LoggingAspect.declareJoinPointExpression()")//重用切点表达式
public void validateArgs(JoinPoint joinPoint) {
System.out.println("validate:" + Arrays.asList(joinPoint.getArgs()));
}
}
package com.cn.spring.aop.impl; import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main {
public static void main(String[] args) {
//1.创建Spring的IOC容器
ApplicationContext ctx = new ClassPathXmlApplicationContext("17-1.xml"); //2.从IOC容器中huo获取bean的实例
ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class); //3.使用bean
int result = arithmeticCalculator.add(3, 6); System.out.println("result:" + result);
//result = arithmeticCalculator.div(3, 0);
// System.out.println("result:" + result);
}
}
<?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.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<context:component-scan base-package="com.cn.spring.aop.impl">
</context:component-scan> <!--使AspjectJ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>
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