欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页

AOP之Hello World

程序员文章站 2022-04-25 20:09:09
...

 目标

package com.aop.joinpoint;

public class Greeting {

	public void greet() {
		System.out.print("World");
	}
	
	public String greetWithParam(String param) {
		System.out.println("Param is " + param);
		return param + ", nice to see you!";
	}

}

 

 环绕通知(又叫包围通知)

package com.aop.advice;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

public class AroundAdvice implements MethodInterceptor {

	@Override
	public Object invoke(MethodInvocation invocation) throws Throwable {
		System.out.print("Hello ");
		Object ret = invocation.proceed();
		System.out.println("!");
		return ret;
	}

}

 

前置通知

package com.aop.advice;

import java.lang.reflect.Method;

import org.springframework.aop.MethodBeforeAdvice;

public class BeforeAdvice implements MethodBeforeAdvice {

	@Override
	public void before(Method method, Object[] arg, Object target) throws Throwable {
		if (arg[0] == null) {
			throw new IllegalArgumentException("arg cannot be null.");
		}
		System.out.println("Before method:" + method.getName() + "(\"" + arg[0] + "\")");
	}

}

 

后置通知

package com.aop.advice;

import java.lang.reflect.Method;

import org.springframework.aop.AfterReturningAdvice;

public class AfterAdvice implements AfterReturningAdvice {

	@Override
	public void afterReturning(Object returningValue, Method method, Object[] arg, Object target) throws Throwable {
		System.out.println("After method:" + method.getName() + "(\"" + arg[0] + "\")");
	}

}

 

手动创建代理

package com.aop.demo;

import org.springframework.aop.framework.ProxyFactory;

import com.aop.advice.AfterAdvice;
import com.aop.advice.AroundAdvice;
import com.aop.advice.BeforeAdvice;
import com.aop.joinpoint.Greeting;

public class GreetingDemo {

	public static void main(String[] args) {
		Greeting target = new Greeting();
		AroundAdvice aroundAdvice = new AroundAdvice();
		BeforeAdvice beforeAdvice = new BeforeAdvice();
		AfterAdvice afterAdvice = new AfterAdvice();

		ProxyFactory pf = new ProxyFactory();
		pf.addAdvice(aroundAdvice);
		pf.setTarget(target);

		Greeting proxy = (Greeting)pf.getProxy();

		//不使用代理
		target.greet();
		System.out.println();

		//使用代理(包围通用)
		proxy.greet();

		System.out.println();
		pf.removeAdvice(aroundAdvice);
		pf.addAdvice(beforeAdvice);
		proxy = (Greeting)pf.getProxy();

		//使用代理(前置通用)
		System.out.println(proxy.greetWithParam("Bruce"));

		System.out.println();
		pf.removeAdvice(beforeAdvice);
		pf.addAdvice(afterAdvice);
		proxy = (Greeting)pf.getProxy();

		//使用代理(后置通用)
		System.out.println(proxy.greetWithParam("David"));
	}

}

 

输出

/**Output:
World
Hello World!

Before method:greetWithParam("Bruce")
Param is Bruce
Bruce, nice to see you!

Param is David
After method:greetWithParam("David")
David, nice to see you!
*/

 

相关标签: AOP