首页 > 代码库 > Spring入门第十八课

Spring入门第十八课

Spring AOP

AspectJ:Java社区里最完整最流行的AOP框架

在Spring2.0以上的版本中,可以使用基于AspectJ注解或者基于XML配置的AOP

看代码:

技术分享

package logan.study.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);
    

}
package logan.study.aop.impl;

import org.springframework.stereotype.Component;

@Component
public class ArithmeticCalculatorImpl implements ArithmeticCalculator {

    @Override
    public int add(int i, int j) {
        // TODO Auto-generated method stub
        int result = i + j;
        return result;
    }

    @Override
    public int sub(int i, int j) {
        // TODO Auto-generated method stub
        int result = i - j;
        return result;
    }

    @Override
    public int mul(int i, int j) {
        // TODO Auto-generated method stub
        int result = i * j;
        return result;
    }

    @Override
    public int div(int i, int j) {
        // TODO Auto-generated method stub
        int result = i / j;
        return result;
    }

}
package logan.study.aop.impl;

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:需要把该类放入到IOC容器中,在声明为一个切面
@Aspect
@Component
public class LoggingAspect {
    //声明该方法时一个前置通知:在目标方法开始之前执行
    @Before("execution(public int logan.study.aop.impl.ArithmeticCalculator.add(int, int))")
    public void beforeMethod(){
        System.out.println("The method begins");
    }

}
<?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">

    <context:component-scan base-package="logan.study.aop.impl"></context:component-scan>
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
    

</beans>
package logan.study.aop.impl;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从IOC容器里面获取bean实例
        ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class);
        //使用Bean
        int result = arithmeticCalculator.add(3, 6);
        System.out.println(result);

    }

}

输出结果:

五月 27, 2017 4:41:38 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@49c2faae: startup date [Sat May 27 16:41:38 CST 2017]; root of context hierarchy
五月 27, 2017 4:41:39 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
The method begins
9

在看代码:

package logan.study.aop.impl;

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

import org.aspectj.lang.JoinPoint;
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:需要把该类放入到IOC容器中,在声明为一个切面
@Aspect
@Component
public class LoggingAspect {
    //声明该方法时一个前置通知:在目标方法开始之前执行
    @Before("execution(public int logan.study.aop.impl.ArithmeticCalculator.add(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 with "+args);
    }

}

输出结果:

五月 27, 2017 5:10:24 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@49c2faae: startup date [Sat May 27 17:10:24 CST 2017]; root of context hierarchy
五月 27, 2017 5:10:24 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
The method add begins with [3, 6]
9

在看代码:

package logan.study.aop.impl;

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

import org.aspectj.lang.JoinPoint;
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:需要把该类放入到IOC容器中,在声明为一个切面
@Aspect
@Component
public class LoggingAspect {
    //声明该方法时一个前置通知:在目标方法开始之前执行
    @Before("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(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 with "+args);
    }

}
package logan.study.aop.impl;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从IOC容器里面获取bean实例
        ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class);
        //使用Bean
        int result = arithmeticCalculator.add(3, 6);
        System.out.println(result);
        
        result = arithmeticCalculator.div(3, 6);
        System.out.println(result);

    }

}

输出结果:

五月 27, 2017 5:12:36 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@49c2faae: startup date [Sat May 27 17:12:36 CST 2017]; root of context hierarchy
五月 27, 2017 5:12:36 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
The method add begins with [3, 6]
9
The method div begins with [3, 6]
0

1.SpringAOP

加入jar包:

spring-aop-4.3.8.RELEASE.jar
spring-aspects-4.3.8.RELEASE.jar
spring-beans-4.3.8.RELEASE.jar
spring-context-4.3.8.RELEASE.jar
spring-core-4.3.8.RELEASE.jar
spring-expression-4.3.8.RELEASE.jar
commons-logging-1.2.jar
aspectjrt.jar
aspectjweaver.jar
aopalliance-1.0.jar
aspectj-1.8.10.jar

在配置文件中加入aop的命名空间

基于注解的方式:

在配置文件中加入如下配置:

<aop:aspectj-autoproxy></aop:aspectj-autoproxy>

把横切关注点的代码抽象到切面的类中

切面首先是一个IOC中的Bean,即加入@Component注解

切面还需要加入@Aspect注解

在类中声明各种通知。

AspectJ支持5中类型的通知注解:

-@Before:前置通知,在方法执行之前执行

-@After:后置通知,在方法执行之后通知

-@AfterRunning:返回通知,在方法返回结果之后执行

-@AfterThrowing:异常通知:在方法抛出异常之后

-@Around:环绕通知,围绕着方法执行。

 

声明一个方法

在方法前加入@Before注解

利用方法签名编写AspectJ切入点表达式

最典型的切入点表达式时根据方法的签名来匹配各种方法:

-execution * logan.aop.ArithmeticCalculator.*(...)匹配ArithmeticCalculator中声明的所有方法,第一个*代表任意修饰符以及任意返回值,第二个*代表任意方法,(...)匹配任意数量的参数,若目标类与接口与切面在同一个包中,可以省略包名。

-execution public * ArithmeticCalculator.*(...):匹配ArithmeticCalculator接口的所有公有方法。

-execution public double ArithmeticCalculator.*(...):匹配ArithmeticCalculator中返回double类型数字的方法。

-execution public double ArithmeticCalculator.*(double,...):匹配ArithmeticCalculator中第一个参数为double类型的,返回double类型数字的方法。

-execution public double ArithmeticCalculator.*(double, double):匹配ArithmeticCalculator中参数类型为(double,double)类型的方法。

 

Spring入门第十八课