AOP面向切片编程的简单理解

面向切面编程(AOP是Aspect Oriented Program的首字母缩写) ,我们知道,面向对象的特点是继承、多态和封装。而封装就要求将功能分散到不同的对象中去,这在软件设计中往往称为职责分配。实际上也就是说,让不同的类设计不同的方法。这样代码就分散到一个个的类中去了。这样做的好处是降低了代码的复杂程度,使类可重用。

懒得去用JDK动态代理,也懒得用CGLIB动态代理,直接简单的反射做个例子。

public static void main(String[] args) {
// TODO Auto-generated method stub

String method = “add”;
try {
Class classz = Class.forName(testService.class.getName());
// Object obj = classz.newInstance();
Object obj = classz.getDeclaredConstructor(String.class).newInstance(“我是参数”);

Method[] methods = classz.getDeclaredMethods();
for (int i = 0; i < methods.length; i++) {
if (methods[i].getName().equals(method)) {
System.out.println(“——befor——:You can do something in here.”);
methods[i].invoke(obj, args);
System.out.println(“——after——:You can do something in here too.”);

}
}

} 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();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

就一个类实例化工厂,然后再调用方法前设置一个before方法,当类方法调用完毕后,再设置一个after方法。

package test;

public class testService {

private final String name;

public testService(String n) {
this.name = n;
}

public void add() {
System.out.println(“invoke Class:”+this.getClass().getName()+” and call the method:add->”+name);
}
}

当然,如果使用CGLIB动态代理会更接单,这里出示网上的一个例子:

代理类

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

public class CglibProxy implements MethodInterceptor {

private Enhancer enhancer = new Enhancer();

public Object getProxy(Class clazz) {
enhancer.setSuperclass(clazz);
enhancer.setCallback(this);
return enhancer.create();
}

public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy)
throws Throwable {
System.out.println(“start…”);
Object result = proxy.invokeSuper(obj, args);
System.out.println(“end…”);
return result;
}
}

接着需要一个实现类:

public class CgService {
public void say(){
System.out.println(“CgService hello”);
}

public void miss(){
System.out.println(“miss game”);
}
}

然后测试:

public class Test {
public static void main(String[] args) throws IOException {
CgService cgService = (CgService) cglibProxy.getProxy(CgService.class);
cgService.say();
cgService.miss();
}
}

 

Leave a Comment