BeanFactory.java的代码
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; } }
ProxyFactoryBean.java的代码
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; } }
测试类BeanFactory.java
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"); } }
配置文件config.properties
nihao=java.util.ArrayList #nihao=com.itAOP.ProxyFactoryBean nihao.advice=com.itAOP.MyAdvice nihao.target=java.util.ArrayList
Advice接口
package com.itAOP; import java.lang.reflect.Method; public interface Advice { public void methodBefore(Method method); public void methodAfter(Method method); }
实现Advice接口的子类MyAdvice.java
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"); } }
黑马程序员——类似于spring的AOP框架
时间: 2024-10-12 19:11:32