package com.itAOP;import java.io.IOException;import java.io.InputStream;import java.util.Properties;/* * 整体的工作原理是这样的： * 工厂类BeanFactory在创建目标类或代理的对象的时候，先由getBean接收一个字符串， * 然后到配置文件中查找器对应的字符串并产生器对象，如果这个对象是ProxyFactoryBean类的 * 实例对象，那么ProxyFactoryBean调用getProxy产生并返回代理对象；如果不是，直接返回 * 这个目标对象。在配置文件中可以切换该字符串的内容 *  * BeanFactory是一个Bean的工厂类，专门用于产生Bean，在它里面调用了一个特殊的类是ProxyFactoryBean * ProxyFactoryBean也是一个Bean，但他同时也是一个Proxy的一个工厂，专门用来产生代理的 *  *///BeanFactory就是负责创建目标类或代理类的对象，并通过配置文件实现切换public class BeanFactory {    //这种配置文件是Propeties格式的    Properties properties = new Properties();    //实例化BeanFactory的时候，需要给他传入一个配置文件，直接就传入一个流了    public BeanFactory(InputStream inputStream){        try {            //将文件加载进来            properties.load(inputStream);        } catch (IOException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    //创建出对应name的对象或代理    public Object getBean(String name){        Object bean = null;        try {            //这就是为什么Bean当中必须有一个无参的构造方法了，newInsatance（）            bean = Class.forName(properties.getProperty(name)).newInstance();        } catch (InstantiationException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (IllegalAccessException e) {            // TODO Auto-generated catch block            e.printStackTrace();        } catch (ClassNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        //判断这个对象是否是ProxyFactory的实例对象        if(bean instanceof ProxyFactoryBean){            Object proxy = null;            ProxyFactoryBean proxyFactoryBean = (ProxyFactoryBean)bean;            try {                Class clazzAdvice = Class.forName(properties.getProperty(name+".advice"));                proxyFactoryBean.setAdvice((Advice)clazzAdvice.newInstance());                Class clazzTarget = Class.forName(properties.getProperty(name+".target"));                proxyFactoryBean.setTarget((Object)clazzTarget.newInstance());                //产生代理对象                proxy = proxyFactoryBean.getProxy();            } catch (ClassNotFoundException e) {                // TODO Auto-generated catch block                e.printStackTrace();            } catch (InstantiationException e) {                // TODO Auto-generated catch block                e.printStackTrace();            } catch (IllegalAccessException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }                        return proxy;                    }        return bean;                            }
}

package com.itAOP;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;public class ProxyFactoryBean {    private Advice advice = null;    private Object target = null;                public Advice getAdvice() {        return advice;    }    public void setAdvice(Advice advice) {        this.advice = advice;    }    public Object getTarget() {        return target;    }    public void setTarget(Object target) {        this.target = target;    }    //方法里主要用到了两个参数，target和advice，这里定义为成员变量    public Object getProxy() {        // TODO Auto-generated method stub        Object objProxy = (Object)Proxy.newProxyInstance(                target.getClass().getClassLoader(),                 target.getClass().getInterfaces(),                 new InvocationHandler(){                    //这里定义一个目标                                        @Override                    public Object invoke(Object proxy, Method method,                            Object[] args) throws Throwable {                        // TODO Auto-generated method stub                        advice.methodBefore(method);                        //在目标上执行代理的那个方法                        Object obj = method.invoke(target, args);                        advice.methodAfter(method);                        return obj;                    }                                    }        );        return objProxy;    }    }

package com.itAOP;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;public class BeanFactoryTest {    /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub                //在Class类里可以通过getResourceAsStream（）来获取InputStream        InputStream inputStream = BeanFactoryTest.class.getResourceAsStream("config.properties");        BeanFactory bean = new BeanFactory(inputStream);        Object obj = bean.getBean("nihao");                System.out.println(obj.getClass().getName());
　　　　   obj.add("123");        }}

nihao=java.util.ArrayList#nihao=com.itAOP.ProxyFactoryBeannihao.advice=com.itAOP.MyAdvicenihao.target=java.util.ArrayList

package com.itAOP;import java.lang.reflect.Method;public interface Advice {    public void methodBefore(Method method);    public void methodAfter(Method method);}

package com.itAOP;import java.lang.reflect.Method;public class MyAdvice implements Advice {    private long beginTime = 0;    @Override    public void methodBefore(Method method) {        // TODO Auto-generated method stub        //我们可以再执行目标的前后干一些其他的事情，比如下面        //System.currentTimeMillis（）返回的当前时间的毫秒        System.out.println("我来了");        beginTime = System.currentTimeMillis();    }    @Override    public void methodAfter(Method method) {        // TODO Auto-generated method stub        long endTime = System.currentTimeMillis();        System.out.println(method.getName()+"......"+(endTime-beginTime));        System.out.println("我走了");    }}