Spring之AOP(二)

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1 通知

package site.exciter.spring.aop.impl;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;

import java.util.Arrays;
import java.util.List;

/**
 * @Aspect当前类声明成一个切面
 */
@Component
@Aspect
public class LoggingAspect {

    /**
     * 前置通知:在目标方法开始执行之前执行
     * <p>
     * execution(* site.exciter.spring.aop.impl. * . * (..))
     * 第一个*表示方法修饰符和反参可以为任意类型,
     * 第二个*代表该包下所有的类,
     * 第三个*表示所有的方法
     * 括号中的..表示目标方法的入参
     *
     * @param point 连接信息
     */
    @Before("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void beforeMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());
        System.out.println("The method " + methodName + " begin 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
     *
     * @param point 连接信息
     */
    @After("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void afterMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end");
    }

    /**
     * 返回通知:在方法正常结束后执行,可以访问到目标方法的返回值
     *
     * @param point  连接信息
     * @param result 返回结果
     */
    @AfterReturning(value = "execution(* site.exciter.spring.aop.impl.*.*(..))", returning = "result")
    public void afterReturning(JoinPoint point, Object result) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end with " + result);
    }

    /**
     * 异常通知:在方法发生异常的时候执行,可以访问到异常对象
     *
     * @param point     连接信息
     * @param exception 异常信息
     */
    @AfterThrowing(value = "execution(* site.exciter.spring.aop.impl.*.*(..))", throwing = "exception")
    public void afterThrowing(JoinPoint point, Exception exception) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " occurs exception: " + exception);
    }

    /**
     * 环绕通知:类似于动态代理的全过程
     * 环绕通知必须有返回值,返回值即为目标方法的返回值
     *
     * @param point ProceedingJoinPoint
     */
    @Around("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public Object aroundMethod(ProceedingJoinPoint point) {
        Object result = null;
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());

        try {
            //前置通知
            System.out.println("The method " + methodName + " begin with " + args);
            //执行目标方法
            result = point.proceed();
            //返回通知
            System.out.println("The method " + methodName + " end with " + result);
        } catch (Throwable e) {
            //异常通知
            System.out.println("The method " + methodName + " occurs exception: " + e);
            e.printStackTrace();
        }
        //后置通知
        System.out.println("The method " + methodName + " end ");
        return result;
    }
}

2 切片优先级

使用@Order(value)来指定切面的优先级,值越小,优先级越高。

验证切面ValidationAspect

package site.exciter.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;

/**
 * 可以使用@Order(value)来指定切面的优先级,值越小,优先级越高
 */
@Order(1)
@Aspect
@Component
public class ValidationAspect {

    @Before("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void validationArgs(JoinPoint point) {
        System.out.println("---> validation:" + Arrays.asList(point.getArgs()));
    }

}

日志切面LoggingAspect

package site.exciter.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;

/**
 * @Aspect当前类声明成一个切面
 */
@Order(2)
@Aspect
@Component
public class LoggingAspect {

    /**
     * 前置通知:在目标方法开始执行之前执行
     * <p>
     * execution(* site.exciter.spring.aop.impl. * . * (..))
     * 第一个*表示方法修饰符和反参可以为任意类型,
     * 第二个*代表该包下所有的类,
     * 第三个*表示所有的方法
     * 括号中的..表示目标方法的入参
     *
     * @param point 连接信息
     */
    @Before("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void beforeMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());
        System.out.println("The method " + methodName + " begin with " + args);
    }
}

结果:

---> validation:[3, 6]
The method add begin with [3, 6]

3 复用切点表达式

1、定义一个方法,使用@Pointcut注解来声明切入表达式。

/**
     * 定义一个方法,专门用来声明切入点表达式,该方法中无需其他代码。
     * 使用@Pointcut来声明切入表达式。
     */
    @Pointcut("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void declareJoinPointExpression() {
    }

2、在其他通知方法中引入1中定义的方法名。

@Before("declareJoinPointExpression()")
    public void beforeMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());
        System.out.println("The method " + methodName + " begin with " + args);
    }

示例:

package site.exciter.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;

/**
 * @Aspect当前类声明成一个切面
 */
@Order(2)
@Aspect
@Component
public class LoggingAspect {

    /**
     * 定义一个方法,专门用来声明切入点表达式,该方法中无需其他代码。
     * 使用@Pointcut来声明切入表达式。
     */
    @Pointcut("execution(* site.exciter.spring.aop.impl.*.*(..))")
    public void declareJoinPointExpression() {
    }

    /**
     * 前置通知:在目标方法开始执行之前执行
     * <p>
     * execution(* site.exciter.spring.aop.impl. * . * (..))
     * 第一个*表示方法修饰符和反参可以为任意类型,
     * 第二个*代表该包下所有的类,
     * 第三个*表示所有的方法
     * 括号中的..表示目标方法的入参
     *
     * @param point 连接信息
     */
    @Before("declareJoinPointExpression()")
    public void beforeMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());
        System.out.println("The method " + methodName + " begin 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
     *
     * @param point 连接信息
     */
    @After("declareJoinPointExpression()")
    public void afterMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end");
    }

    /**
     * 返回通知:在方法正常结束后执行,可以访问到目标方法的返回值
     *
     * @param point  连接信息
     * @param result 返回结果
     */
    @AfterReturning(value = "declareJoinPointExpression()", returning = "result")
    public void afterReturning(JoinPoint point, Object result) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end with " + result);
    }

    /**
     * 异常通知:在方法发生异常的时候执行,可以访问到异常对象
     *
     * @param point     连接信息
     * @param exception 异常信息
     */
    @AfterThrowing(value = "declareJoinPointExpression()", throwing = "exception")
    public void afterThrowing(JoinPoint point, Exception exception) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " occurs exception: " + exception);
    }

    /**
     * 环绕通知:类似于动态代理的全过程
     * 环绕通知必须有返回值,返回值即为目标方法的返回值
     *
     * @param point ProceedingJoinPoint
     */
    @Around("declareJoinPointExpression()")
    public Object aroundMethod(ProceedingJoinPoint point) {
        Object result = null;
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());

        try {
            //前置通知
            System.out.println("The method " + methodName + " begin with " + args);
            //执行目标方法
            result = point.proceed();
            //返回通知
            System.out.println("The method " + methodName + " end with " + result);
        } catch (Throwable e) {
            //异常通知
            System.out.println("The method " + methodName + " occurs exception: " + e);
            e.printStackTrace();
        }
        //后置通知
        System.out.println("The method " + methodName + " end ");
        return result;
    }
}
package site.exciter.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;

/**
 * 可以使用@Order(value)来指定切面的优先级,值越小,优先级越高
 */
@Order(1)
@Aspect
@Component
public class ValidationAspect {

    /**
     * 引入其他包或类下的切入点方法,需要加上包名或类名
     *
     * @param point
     */
    @Before("site.exciter.spring.aop.impl.LoggingAspect.declareJoinPointExpression()")
    public void validationArgs(JoinPoint point) {
        System.out.println("---> validation:" + Arrays.asList(point.getArgs()));
    }

}

4 配置文件的方式配置AOP

1 代码中不使用任何注解

package site.exciter.spring.aop.xml;

public interface IArithmeticCalculator {
    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 site.exciter.spring.aop.xml;

public class ArithmeticCalculatorImpl implements IArithmeticCalculator {

    @Override
    public int add(int i, int j) {
        return i + j;
    }

    @Override
    public int sub(int i, int j) {
        return i - j;
    }

    @Override
    public int mul(int i, int j) {
        return i * j;
    }

    @Override
    public int div(int i, int j) {
        return i / j;
    }
}
package site.exciter.spring.aop.xml;

import org.aspectj.lang.JoinPoint;

import java.util.Arrays;

public class ValidationAspect {

    public void validationArgs(JoinPoint point) {
        System.out.println("---> validation:" + Arrays.asList(point.getArgs()));
    }

}
package site.exciter.spring.aop.xml;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;

import java.util.Arrays;
import java.util.List;

public class LoggingAspect {

    public void beforeMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());
        System.out.println("The method " + methodName + " begin with " + args);
    }

    public void afterMethod(JoinPoint point) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end");
    }

    public void afterReturning(JoinPoint point, Object result) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " end with " + result);
    }

    public void afterThrowing(JoinPoint point, Exception  exception) {
        String methodName = point.getSignature().getName();
        System.out.println("The method " + methodName + " occurs exception: " + exception);
    }

    public Object aroundMethod(ProceedingJoinPoint point) {
        Object result = null;
        String methodName = point.getSignature().getName();
        List<Object> args = Arrays.asList(point.getArgs());

        try {
            //前置通知
            System.out.println("The method " + methodName + " begin with " + args);
            //执行目标方法
            result = point.proceed();
            //返回通知
            System.out.println("The method " + methodName + " end with " + result);
        } catch (Throwable e) {
            //异常通知
            System.out.println("The method " + methodName + " occurs exception: " + e);
            e.printStackTrace();
        }
        //后置通知
        System.out.println("The method " + methodName + " end ");
        return result;
    }
}

2 在配置文件中配置AOP

applicationContext-xml.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"
       xmlns:context="http://www.springframework.org/schema/context"
       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-4.2.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd">

    <!--  配置Bean  -->
    <bean id="arithmeticCalculator" class="site.exciter.spring.aop.xml.ArithmeticCalculatorImpl"/>

    <!--  配置切面的Bean  -->
    <bean id="loggingAspect" class="site.exciter.spring.aop.xml.LoggingAspect"/>
    <bean id="validationAspect" class="site.exciter.spring.aop.xml.ValidationAspect"/>

    <!--  配置AOP  -->
    <aop:config>
        <!--    配置切面表达式    -->
        <aop:pointcut id="pointcut" expression="execution(* site.exciter.spring.aop.xml.*.*(..))"/>
        <!--    配置切面及通知    -->
        <aop:aspect ref="validationAspect" order="1">
            <!--      配置切面方法      -->
            <aop:before method="validationArgs" pointcut-ref="pointcut"/>
        </aop:aspect>
        <aop:aspect ref="loggingAspect" order="2">
            <aop:before method="beforeMethod" pointcut-ref="pointcut"/>
            <aop:after method="afterMethod" pointcut-ref="pointcut"/>
            <aop:after-returning method="afterReturning" pointcut-ref="pointcut" returning="result"/>
            <aop:after-throwing method="afterThrowing" pointcut-ref="pointcut" throwing="exception"/>
        </aop:aspect>
    </aop:config>

</beans>

3 测试

package site.exciter.spring.aop.xml;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

    @org.junit.Test
    public void testImpl() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext-xml.xml");
        IArithmeticCalculator calculator = (IArithmeticCalculator) context.getBean("arithmeticCalculator");

        int result = calculator.add(3, 6);
        System.out.println("result-->" + result);

        result = calculator.div(12, 2);
        System.out.println("result-->" + result);
    }
}

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