動態代理,作為實現AOP的方式之一,已經得到廣泛的應用.本人看了很多書關于動態代理的介紹,基本就是不知所云. 所以最終自己做了一個例子,才感到有點明白,下面是我的代碼
(注: 說明同一個包里面的類的類加載器(ClassLoader)是一樣的)
package
?pear;?
??
//
import?org.springframework.aop.Advisor;?
//
import?org.springframework.aop.BeforeAdvice;?
import
?java.lang.reflect.
*
;?
??
interface
?SayInterface
{??????????
//
?被代理接口?
???????
public
?
void
?say();?
???????
public
?
void
?saytwo();?
}
?
class
?Say?
implements
?SayInterface
{????
//
?被代理的類?
???????
public
?
void
?say()
{?
??????????????System.out.println(
"
?in?say?
"
);?
???????}
?
???????
public
?
void
?saytwo()
{?
??????????????System.out.println(
"
in?say?2
"
);?
???????}
?
}
?
??
class
?SayHandler?
implements
?InvocationHandler
{?????
//
?
???????
private
?Say?mysay?
=
?
new
?Say();?????????
//
先生成一個"被代理類"的對象?
???????
public
?Object?invoke(Object?proxy,Method?method,Object[]?args)
throws
?Exception
{?
??????????????System.out.println(
"
Before
"
);????
//
方法調用之前輸出Before?
???????????method.invoke(mysay,args);?????????
//
原來方法在這里才真正被調用?
??????????????
//
method.invoke(saytwo,args);?
??????????????System.out.println(
"
After
"
);??????
//
方法調用之后輸出After?
??????????????
return
?
null
;?
???????}
?
}
?
??
public
?
class
?Main?
{?
?
/**?*/
/**
??*?
@param
?args
??
*/
?
public
?
static
?
void
?main(String[]?args)?
{
??
//
?TODO?Auto-generated?method?stub
??SayHandler?handler?
=
?
new
?SayHandler();
??SayInterface?si?
=
?(SayInterface)Proxy.newProxyInstance(
????SayInterface.
class
.getClassLoader(),
new
?Class[]
{SayInterface.
class
}
,handler);
/**?*/
/**
??SayInterface?si?=?(SayInterface)Proxy.newProxyInstance(
//???????handler.getClass().getClassLoader(),handler.say.getClass().getInterfaces(),handler);
??//被代理接口的類加載器，被加載的類，和。。。。
????????SayInterface?si?=?(SayInterface)Proxy.newProxyInstance(handler.getClass().getClassLoader(),);???
*/
?
???si.say();
??si.saytwo();
??System.out.println(
"
the?end.
"
);
?}
?
}