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

xxx.target

xxx.advice

配置文件

config.propertiest

• 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

• 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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