Spring攻略学习笔记(3.01)在Spring中启用AspectJ注解支持

一、知识点    

       Spring支持在其AOP框架中使用AspectJ注解编写POJO aspect。但是，必须先在Spring IoC容器中启 用AspecJ注解支持。

        只需要在Bean配置文件中定义一个空的XML元素<aop:aspectj-autoproxy>就可以启用Spring IoC容器中AspectJ注解支持。然后，Spring将自动为匹配你的AspectJ aspect的 所有Bean创建代理。

        对于接口不可用或者没有用于应用程序设计中的情况，可以依靠CGLIB创建代理。为了启用 CGLIB创建代理,必须在<aop:aspectj-autoproxy>中设置 proxy-targetclass= true 属性。

二、代码示例
        计算器接口   

package com.codeproject.jackie.springrecipesnote.springaop;

/**
 * 加减乘除
 * @author jackie
 * 
 */
public interface ArithmeticCalculator {
	
	/**
	 * 加
	 * @param a
	 * @param b
	 * @return
	 */
	public double add(double a, double b);

	/**
	 * 减
	 * @param a
	 * @param b
	 * @return
	 */
	public double sub(double a, double b);

	/**
	 * 乘
	 * @param a
	 * @param b
	 * @return
	 */
	public double mul(double a, double b);

	/**
	 * 除
	 * @param a
	 * @param b
	 * @return
	 */
	public double div(double a, double b);
}

package com.codeproject.jackie.springrecipesnote.springaop;

/**
 * 单位转换
 * @author jackie
 * 
 */
public interface UnitCalculator {
	
	/**
	 * 千克（或公斤）转换成磅
	 * @param kilogram
	 * @return
	 */
	public double kilogramToPound(double kilogram);

	/**
	 * 千米转换成英里
	 * @param kilometer
	 * @return
	 */
	public double kilometerToMile(double kilometer);
}

相应的实现类

package com.codeproject.jackie.springrecipesnote.springaop;

/**
 * 加减乘除实现类
 * @author jackie
 * 
 */
public class ArithmeticCalculatorlmpl implements ArithmeticCalculator {

	public double add(double a, double b) {
		double result = a + b;
		System.out.println(a + " + " + b + " = " + result);
		return result;
	}

	public double sub(double a, double b) {
		double result = a - b;
		System.out.println(a + " - " + b + " = " + result);
		return result;
	}

	public double mul(double a, double b) {
		double result = a * b;
		System.out.println(a + " * " + b + " = " + result);
		return result;
	}

	public double div(double a, double b) {
		if (b == 0) {
			throw new IllegalArgumentException("Division by zero");
		}
		double result = a / b;
		System.out.println(a + " / " + b + " = " + result);
		return result;
	}
}

package com.codeproject.jackie.springrecipesnote.springaop;

/**
 * 单位转换实现类
 * @author jackie
 * 
 */
public class UnitCalculatorImpl implements UnitCalculator {

	public double kilogramToPound(double kilogram) {
		double pound = kilogram * 2.2;
		System.out.println(kilogram + " kilogram = " + pound + " pound");
		return pound;
	}

	public double kilometerToMile(double kilometer) {
		double mile = kilometer * 0.62;
		System.out.println(kilometer + " kilometer = " + mile + " mile");
		return mile;
	}
}

       为了启用这个应用的AspectJ注解支持，你只要在Bean配置文件中定义一个空的XML元素<aop:aspectj-autoproxy>。而且，你必须将aop schema定义添加到<beans>根元素下。当Spring IoC容器发现Bean配置文件中的<aop:aspectj-autoproxy>元素,它将自动为匹配AspecJ aspect的Bean创建代理。

       注：如果使用Maven管理依赖，需添加以下依赖

                <dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>${springframework.version}</version>
		</dependency>

		<!-- AspectJ -->
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjrt</artifactId>
			<version>1.7.2</version>
		</dependency>
		<dependency>
			<groupId>org.aspectj</groupId>
			<artifactId>aspectjweaver</artifactId>
			<version>1.7.2</version>
		</dependency>

<?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-3.2.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">    
	<aop:aspectj-autoproxy />
   
	<bean id="arithmeticCalculator" class="com.codeproject.jackie.springrecipesnote.springaop.ArithmeticCalculatorlmpl" />
	<bean id="unitCalculator" class="com.codeproject.jackie.springrecipesnote.springaop.UnitCalculatorImpl" />
</beans>

测试方法 

        @Test
	public void testAop() {
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		ArithmeticCalculator arithmeticCalculator = (ArithmeticCalculator)applicationContext.getBean("arithmeticCalculator");
		arithmeticCalculator.add(1, 2);
		arithmeticCalculator.sub(1, 2);
		arithmeticCalculator.mul(1, 2);
		arithmeticCalculator.div(1, 2);
		
		UnitCalculator unitCalculator = (UnitCalculator) applicationContext.getBean("unitCalculator");
		unitCalculator.kilogramToPound(100);
		unitCalculator.kilometerToMile(100);	
	}