Java实现AOP功能的封装与配置的小框架实例代码

本文通过是动态代理实现的AOP功能的封装与配置的小框架.加深对动态代理和AOP编程的理解

设计

根据配置文件的键xxx对应的值(类全名)创建相应类的对象。

当且仅当xxx对应的值为com.iot.proxy.aopframework.ProxyFactoryBean时，则生成相应的动态代理类对象。代理对象的目标类和通知实现类分别由xxx.target和xxx.advice配置

配置文件

config.propertiest位于aopframework包下

• xxx代表要加载的类
• xxx.advice代表通知接口的某个实现类
• xxx.target代表委托类

#xxx=java.util.ArrayList
xxx=com.iot.proxy.aopframework.ProxyFactoryBean
xxx.advice=com.iot.proxy.MyAdvice
xxx.target=java.util.ArrayList

包:com.iot.proxy.aopframework,有如下几个类/接口：

• BeanFactory,用于读取配置文件，根据配置创建相应的对象
• ProxyFactoryBean,用于生成代理对象，含有两个私有属性:目标和通知
• Advice,通知接口，用于把切面的代码以对象的形式传递给InvocationHandler的的invoke方法
• MyAdvice,Advice接口的一个实现类，打印执行方法前的时间及执行耗时
• AopFrameWorkTest，测试效果
  

代码

Advice接口

package com.iot.proxy.aopframework;import java.lang.reflect.Method;/** * Created by brian on 2016/2/2. */public interface Advice {  void beforeMethod(Method method);  void aftereMethod(Method method);}

MyAdvice类

package com.iot.proxy.aopframework;import java.lang.reflect.Method;/** * Created by brian on 2016/2/2. */public class MyAdvice implements Advice{long beginTime = 0 ;@Override  public void beforeMethod(Method method) {System.out.println(method.getName()+" before at "+beginTime);beginTime = System.currentTimeMillis();}@Override  public void aftereMethod(Method method) {long endTime = System.currentTimeMillis();System.out.println(method.getName()+" cost total "+ (endTime-beginTime));}}

BeanFactory类

package com.iot.proxy.aopframework;import java.io.IOException;import java.io.InputStream;import java.util.Properties;/** * Created by brian on 2016/2/2. */public class BeanFactory {Properties properties = new Properties();public BeanFactory(InputStream inputStream){try {properties.load(inputStream);}catch (IOException e) {e.printStackTrace();}}public Object getBean(String name){String className = properties.getProperty(name);Object bean = null;try {Class clazz = Class.forName(className);bean = clazz.newInstance();}catch (ClassNotFoundException e) {e.printStackTrace();}catch (InstantiationException e) {e.printStackTrace();}catch (IllegalAccessException e) {e.printStackTrace();}if (bean instanceof ProxyFactoryBean){ProxyFactoryBean proxyFactoryBean = (ProxyFactoryBean)bean;Advice advice = null;Object target = null;try {advice = (Advice) Class.forName(properties.getProperty(name+".advice")).newInstance();target = Class.forName(properties.getProperty(name+".target")).newInstance();}catch (InstantiationException e) {e.printStackTrace();}catch (IllegalAccessException e) {e.printStackTrace();}catch (ClassNotFoundException e) {e.printStackTrace();}proxyFactoryBean.setAdvice(advice);proxyFactoryBean.setTarget(target);Object proxy = ((ProxyFactoryBean) bean).getProxy();return proxy;}return bean;}}

ProxyFactoryBean类

package com.iot.proxy.aopframework;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;/** * Created by brian on 2016/2/3. */public class ProxyFactoryBean {private Object target;private Advice advice;public Object getProxy(){Object proxy = Proxy.newProxyInstance(        target.getClass().getClassLoader(),        target.getClass().getInterfaces(),        new InvocationHandler() {@Override          public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {advice.beforeMethod(method);Object retVal = method.invoke(target,args);advice.aftereMethod(method);return retVal;}});return proxy;}public Object getTarget() {return target;}public void setTarget(Object target) {this.target = target;}public Advice getAdvice() {return advice;}public void setAdvice(Advice advice) {this.advice = advice;}}

AopFrameWorkTest类

package com.iot.proxy.aopframework;import java.io.InputStream;import java.util.Collection;/** * Created by brian on 2016/2/3. */public class AopFrameWorkTest {public static void main(String[] args) {InputStream inputStream = AopFrameWorkTest.class.getResourceAsStream("config.properties");Object bean = new BeanFactory(inputStream).getBean("xxx");System.out.println(bean.getClass().getName());((Collection) bean).clear();}}

输出

• 配置xxx=com.iot.proxy.aopframework.ProxyFactoryBean
  

输出为：

com.sun.proxy.$Proxy0
clear before at 0
clear cost total 0

• 配置xxx=java.util.ArrayList

输出为：

java.util.ArrayList

可以看出，只改变配置文件，就可改变代码的运行结果，从而达到灵活的效果

总结

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