aspectJ面向切面编程

java

一件事情，对你伤害的程度与事情本身没有任何关系，取决于你对这件事情的态度。

aop的实现我目前了解的有两种，一种是通过动态代理（实现InvocationHandler接口或者用第三方cglib库，两者区别这就不介绍了），另一种是aspectJ。aspectJ基本环境搭建，首先eclipse安装插件，aspect基本用法可以参考官方官方文档

一.Aspect基本用法，代码如下：

1.创建基本的main入口 

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package com.zlc.aj;
public class Test {
	public void sayHello() {
		System.out.println("Hello");
	}
	public static void main(String[] args) {
		Test t = new Test();
		t.sayHello();
	}
}

2.给Test里sayHollo添加切入点 

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pointcut sayHelloPointCut() : execution(* com.zlc.aj.Test.sayHello(..));
before() : sayHelloPointCut() {
	System.out.println("PointCut开始事务 ...");
}

void around() : call(void com.zlc.aj.Test.sayHello()) {
	System.out.println("开始事务 ...");
	proceed();
	System.out.println("事务结束 ...");
}

更多用法参考官方文档，或者兔子党-大胡子博客

二.Aspect通过自定义注解实现统计，代码如下：

1.创建自定义注解 

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@Retention(RetentionPolicy.CLASS)
@Target({ElementType.CONSTRUCTOR, ElementType.METHOD})
public @interface DebugTrace {
}

2.给注解添加切入点 

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package com.zlc.annotation;
@Aspect
public class DebugTraceAspect {
	private static final String POINTCUT_METHOD = "execution(@com.zlc.annotation.DebugTrace * *(..))";
	private static final String POINTCUT_CONSTRUCTOR = "execution(@com.zlc.annotation.DebugTrace *.new(..))";

	@Pointcut(POINTCUT_METHOD)
	public void methodAnnotatedWithDebugTrace() {
	}

	@Pointcut(POINTCUT_CONSTRUCTOR)
	public void constructorAnnotatedDebugTrace() {
	}

	@Around("methodAnnotatedWithDebugTrace() || constructorAnnotatedDebugTrace()")
	public Object weaveJoinPoint(ProceedingJoinPoint joinPoint) throws Throwable {
		CodeSignature methodSignature = (CodeSignature) joinPoint.getSignature();
		String className = methodSignature.getDeclaringType().getSimpleName();
		String methodName = methodSignature.getName();

		final StopWatch stopWatch = new StopWatch();
		stopWatch.start();
		Object result = joinPoint.proceed();
		stopWatch.stop();

		log(className, buildLogMessage(methodName, stopWatch.getTotalTimeMillis()));
		return result;
	}

	private static String buildLogMessage(String methodName, long methodDuration) {
		StringBuilder message = new StringBuilder();
		message.append(methodName);
		message.append(" --> ");
		message.append("[");
		message.append(methodDuration);
		message.append("ms");
		message.append("]");
		return message.toString();
	}
	
	public static void log(String tag, String message) {
		System.out.println(tag + " --> " + message);
	}
}

相关类：
StopWatch.java,
DebugTeaceTest.java

三.Android使用aspectJ：

1.基于AOP的非侵入式监控之——AspectJ实战
http://blog.csdn.net/woshimalingyi/article/details/51476559
2.android studio中使用AspectJ实战
http://blog.csdn.net/woshimalingyi/article/details/51519851