谁能说说@AspectJ中this和target这两个切点标识符的具体区别

引用
this - limits matching to join points (the execution of methods when using Spring AOP) where the bean
reference (Spring AOP proxy) is an instance of the given type
• target - limits matching to join points (the execution of methods when using Spring AOP) where the target
object (application object being proxied) is an instance of the given type

似乎看不出两者的具体区别，我试着做了一个测试：
切面定义类：

Java代码 收藏代码
package com.baobaotao.expression;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
@Aspect
public class PreGreetingAspect{
@Before("target(com.baobaotao.expression.NaiveWaiter)")
public void beforeGreeting(){
System.out.println("How are you");
}
}

目标类接口：
Java代码 收藏代码
package com.baobaotao.expression;

public interface Waiter {
public void greetTo(String name);
public void serveTo(String name);
}

目标接口实现类：
Java代码 收藏代码
package com.baobaotao.expression;

public class NaiveWaiter implements Waiter {
public void greetTo(String name) {
System.out.println("greet to "+name+"...");
}
public void serveTo(String name){
System.out.println("serving "+name+"...");
foo(name);
}
public void foo(String name){
System.out.println("foo "+name+"...");
}
}

然后是配置：
Java代码 收藏代码