目录
一、环境配置
首先，创建service层方法div，及其代理类MethodAOP：
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package club.affengkuang.computer.service;
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import org.springframework.stereotype.Service;
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//服务层
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@Service
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public
class ComputerService implements IComputerService{
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public int div(int a, int b) {
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return a/b;
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}
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}
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package club.affengkuang.aop;
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import org.aspectj.lang.JoinPoint;
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import org.aspectj.lang.Signature;
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//代理类
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public
class MethodAOP {
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public void before(JoinPoint jp) {
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Object [] args = jp.getArgs();
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Signature signature = jp.getSignature();
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String name = signature.getName();
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System.out.println(
"the "+name+
" method begins.");
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System.out.println(
"the "+name+
" method param ["+args[
0]+
","+args[
1]+
"]");
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}
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}
application.xml文件的配置如下：
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<?xml version="1.0" encoding="UTF-8"?>
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<beans xmlns="http://www.springframework.org/schema/beans"
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xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
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xmlns:context=
"http://www.springframework.org/schema/context"
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xmlns:aop=
"http://www.springframework.org/schema/aop"
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xmlns:p=
"http://www.springframework.org/schema/p"
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xmlns:tx=
"http://www.springframework.org/schema/tx"
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xsi:schemaLocation=
"http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd
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http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
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http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
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http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
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<context:component-scan base-package="club.affengkuang">
</context:component-scan>
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<bean id="ma" class="club.affengkuang.aop.MethodAOP">
</bean>
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<aop:config>
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<!-- 定义一个aop表达式 -->
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<aop:pointcut expression="execution(public int club.affengkuang.computer.service.ComputerService.*(..))" id="pc"/>
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<!-- 设置一个切面类 -->
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<aop:aspect ref="ma">
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<aop:before method="before" pointcut-ref="pc"/>
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</aop:aspect>
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</aop:config>
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</beans>
二、如何启动两种代理类
在如下测试类中调用div方法，并打印代理类类名，得到的该类名就是默认的JDK代理类：
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package club.affengkuang.test;
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import org.springframework.context.support.ClassPathXmlApplicationContext;
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import club.affengkuang.computer.service.IComputerService;
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public
class Test {
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public static void main(String[] args) {
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ClassPathXmlApplicationContext applicationContext =
new ClassPathXmlApplicationContext(
"application.xml");
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IComputerService computerService = applicationContext.getBean(IComputerService.class);
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System.out.println(computerService.div(
1,
1));
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System.out.println(computerService.getClass().getName());
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applicationContext.close();
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}
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}
启动CGlib代理类，只需在application.xml文件中aop：config标签头部将proxy-target-class属性赋值为true即可，该属性默认值为false，也就是默认使用JDK代理类，赋值为true后使用的便是CGlib代理类：
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<aop:config proxy-target-class="true">
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<!-- 定义一个aop表达式 -->
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<aop:pointcut expression="execution(public int club.affengkuang.computer.service.ComputerService.*(..))" id="pc"/>
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<!-- 设置一个切面类 -->
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<aop:aspect ref="ma">
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<aop:before method="before" pointcut-ref="pc"/>
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</aop:aspect>
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</aop:config>
这时再调用测试类打印代理类类名，得到的便是CGlib代理类类名：
三、JDK代理类与CGlib代理类区别
JDK代理类：代理类和目标类无直接继承关系，代理类实现的是目标类实现的接口
CGlib代理类：直接继承自目标类
1.证明
如下：首先设置成JDK代理类，并在测试类中输出代理类所实现的接口，得到了目标类所实现的IComputerService接口：
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package club.affengkuang.test;
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import org.springframework.context.support.ClassPathXmlApplicationContext;
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import club.affengkuang.computer.service.IComputerService;
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public
class Test {
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@SuppressWarnings(
"rawtypes")
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public static void main(String[] args) {
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ClassPathXmlApplicationContext applicationContext =
new ClassPathXmlApplicationContext(
"application.xml");
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IComputerService computerService = applicationContext.getBean(IComputerService.class);
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Class clazz = computerService.getClass();
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for(Class c:clazz.getInterfaces()) {
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System.out.println(c);
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}
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applicationContext.close();
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}
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}
再将其设置成CGlib代理类，并在测试类中打印所继承的父类，得到了目标类：
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package club.affengkuang.test;
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import org.springframework.context.support.ClassPathXmlApplicationContext;
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import club.affengkuang.computer.service.IComputerService;
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public
class Test {
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@SuppressWarnings(
"rawtypes")
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public static void main(String[] args) {
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ClassPathXmlApplicationContext applicationContext =
new ClassPathXmlApplicationContext(
"application.xml");
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IComputerService computerService = applicationContext.getBean(IComputerService.class);
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Class clazz = computerService.getClass();
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System.out.println(clazz.getSuperclass());
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applicationContext.close();
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}
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}
2.影响
CGlib代理类直接继承自目标类，也就意味着在IOC容器中既可以通过目标类实现的接口获取代理类，也可以通过目标类获取代理类，将第13行getBean方法的参数改为通过目标类获取，同样可以得到代理类：
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package club.affengkuang.test;
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import org.springframework.context.support.ClassPathXmlApplicationContext;
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import club.affengkuang.computer.service.ComputerService;
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import club.affengkuang.computer.service.IComputerService;
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public
class Test {
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@SuppressWarnings(
"rawtypes")
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public static void main(String[] args) {
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ClassPathXmlApplicationContext applicationContext =
new ClassPathXmlApplicationContext(
"application.xml");
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IComputerService computerService = applicationContext.getBean(ComputerService.class);
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System.out.println(computerService.getClass().getName());
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applicationContext.close();
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}
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}
而JDK代理类和目标类无直接继承关系，所以只能通过接口获取代理类，将proxy-target-class属性改为false，即使用JDK代理类，再执行上述测试类，则会抛出异常：
转载：https://blog.csdn.net/DangerousMc/article/details/104920729
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