Spring AOP 学习小结

package com.longthsoft.learn.spring;

import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class SimpleAspect {

@Pointcut("execution(* com.longthsoft.learn.spring.models.*.say*())")
public void simplePointcut() { }

@AfterReturning(pointcut="simplePointcut()")
public void simpleAdvice() {
System.out.println("Merry Christmas");
}
}
这段代码不明白！！！

Aspect：这个我一直迷惑，它实际是Advice和Pointcut的组合，但是Spring AOP 中的Advisor也是这样一个东西，但是Spring中为什么叫Advisor而不叫做Aspect

三、Spring AOP 代理原理
Spring AOP 是使用代理来完成的，Spring 会使用下面两种方式的其中一种来创建代理：
1、JDK动态代理，特点只能代理接口，性能相对较差，需要设定一组代理接口。
2、CGLIB 代理，可代理接口和类（final method除外），性能较高(生成字节码)。

Imagine that in our example above, there was no Person interface: we needed to advise a class called Person that didn't implement any business interface. In this case, you can configure Spring to use CGLIB proxying, rather than dynamic proxies. Simply set the proxyTargetClass property on the ProxyFactoryBean above to true. While it's best to program to interfaces, rather than classes, the ability to advise classes that don't implement interfaces can be useful when working with legacy code. (In general, Spring isn't prescriptive. While it makes it easy to apply good practices, it avoids forcing a particular approach.)

There's little performance difference between CGLIB proxying and dynamic proxies. As of Spring 1.0, dynamic proxies are slightly faster. However, this may change in the future. Performance should not be a decisive consideration in this case

Pointcut: A predicate that matches join points. Advice is associated with a pointcut expression and runs at any join point matched by the pointcut (for example, the execution of a method with a certain name). The concept of join points as matched by pointcut expressions is central to AOP: Spring uses the AspectJ pointcut language by default.

A pointcut is a collection of joinpoints that you use to define when advice should be executed. By creating pointcuts, you gain fine-grained control over how you apply advice to the components in your application. As mentioned previously, a typical joinpoint is a method invocation. A typical pointcut is the collection of all method invocations in a particular class. Often you can compose pointcuts in complex relationships to further constrain when advice is executed. We discuss pointcut composition in more detail in the next chapter.