Java實現AOP功能的封裝與配置的小框架實例代碼

本文通過是動態代理實現的AOP功能的封裝與配置的小框架.加深對動態代理和AOP編程的理解

設計

根據配置文件的鍵xxx對應的值(類全名)創建相應類的對象。

當且僅當xxx對應的值為com.iot.proxy.aopframework.ProxyFactoryBean時，則生成相應的動態代理類對象。代理對象的目標類和通知實現類分別由xxx.target和xxx.advice配置

配置文件

config.propertiest位於aopframework包下

• xxx代表要加載的類
• xxx.advice代表通知接口的某個實現類
• xxx.target代表委託類

#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 ,有如下幾個類/接口：

• BeanFactory,用於讀取配置文件，根據配置創建相應的對象
• ProxyFactoryBean,用於生成代理對象，含有兩個私有屬性:目標和通知
• Advice,通知接口，用於把切面的代碼以對象的形式傳遞給InvocationHandler的的invoke方法
• MyAdvice,Advice接口的一個實現類，打印執行方法前的時間及執行耗時
• AopFrameWorkTest，測試效果
  

代碼

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類

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類

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類

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類

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();}}

輸出

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

輸出為：

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

• 配置xxx=java.util.ArrayList

輸出為：

java.util.ArrayList

可以看出，只改變配置文件，就可改變代碼的運行結果，從而達到靈活的效果

總結

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