spring4中文技術(shù)手冊

spring4中文技術(shù)手冊在《靜態(tài)代理和動態(tài)代理》中提到了面對方面編程，重要就是基于動態(tài)代理。單獨抽象出非業(yè)務(wù)的功效，服務(wù)于某些業(yè)務(wù)辦法。Spring提供了四種很實用的Advice，分別為：BeforeAdvice,AfterReturningAdvice,AroundAdvice,AfterthrowingAdvice。都是辦法級別的，就是在某個辦法執(zhí)行前后插入某些非業(yè)務(wù)的操作，如打日志或者判斷權(quán)限等。對于這四種advice的實現(xiàn)，spring都提供了三種辦法，分別為基于接口、基于xml和基于annotation(注釋)。BeforeAdvice會在目的對象的辦法執(zhí)行之前被調(diào)用；AfterAdvice會在目的辦法執(zhí)行之后被調(diào)用；AroundAdvice則能夠在目的辦法執(zhí)行前后同時加上有關(guān)服務(wù)；ThrowAdvice是在異常發(fā)生后執(zhí)行某些操作。1.基于接口的Advice這個就需要自定義的Aspect實現(xiàn)Spring接口。BeforeAdvice需要實現(xiàn)org.springframework.aop.MethodBeforeAdvice接口：/**

*

Advice

invoked

before

a

method

is

invoked.

Such

advices

cannot

*

prevent

the

method

call

proceeding,

unless

they

throw

a

Throwable.

*/

public

interface

MethodBeforeAdvice

extends

BeforeAdvice

{

/**

*

Callback

before

a

given

method

is

invoked.

*

@param

method

method

being

invoked

*

@param

args

arguments

to

the

method

*

@param

target

target

of

the

method

invocation.

May

be

<code>null</code>.

*

@throws

Throwable

if

this

object

wishes

to

abort

the

call.

*

Any

exception

thrown

will

be

returned

to

the

caller

if

it's

*

allowed

by

the

method

signature.

Otherwise

the

exception

*

will

be

wrapped

as

a

runtime

exception.

*/

void

before(Method

method,

Object[]

args,

Object

target)

throws

Throwable;

}

AfterAdvice實現(xiàn)org.springframework.aop.AfterReturningAdvice接口：/**

*

After

returning

advice

is

invoked

only

on

normal

method

return,

not

if

an

*

exception

is

thrown.

Such

advice

can

see

the

return

value,

but

cannot

change

it.

*/

public

interface

AfterReturningAdvice

extends

AfterAdvice

{

/**

*

Callback

after

a

given

method

successfully

returned.

*

@param

returnValue

the

value

returned

by

the

method,

if

any

*

@param

method

method

being

invoked

*

@param

args

arguments

to

the

method

*

@param

target

target

of

the

method

invocation.

May

be

<code>null</code>.

*

@throws

Throwable

if

this

object

wishes

to

abort

the

call.

*

Any

exception

thrown

will

be

returned

to

the

caller

if

it's

*

allowed

by

the

method

signature.

Otherwise

the

exception

*

will

be

wrapped

as

a

runtime

exception.

*/

void

afterReturning(Object

returnValue,

Method

method,

Object[]

args,

Object

target)

throws

Throwable;

}

AroundAdvice需要實現(xiàn)ercept.MethodInterceptor接口：/**

*

<p>The

user

should

implement

the

{@link

#invoke(MethodInvocation)}

*

method

to

modify

the

original

behavior.

E.g.

the

following

class

*

implements

a

tracing

interceptor

(traces

all

the

calls

on

the

*

intercepted

method(s)):

*

*

<pre

class=code>

*

class

TracingInterceptor

implements

MethodInterceptor

{

*

Object

invoke(MethodInvocation

i)

throws

Throwable

{

*

System.out.println("method

"+i.getMethod()+"

is

called

on

"+

*

i.getThis()+"

with

args

"+i.getArguments());

*

Object

ret=ceed();

*

System.out.println("method

"+i.getMethod()+"

returns

"+ret);

*

return

ret;

*

}

*

}

*

</pre>

*/

public

interface

MethodInterceptor

extends

Interceptor

{

/**

*

Implement

this

method

to

perform

extra

treatments

before

and

*

after

the

invocation.

Polite

implementations

would

certainly

*

like

to

invoke

{@link

Joinpoint#proceed()}.

*

*

@param

invocation

the

method

invocation

joinpoint

*

@return

the

result

of

the

call

to

{@link

*

Joinpoint#proceed()},

might

be

intercepted

by

the

*

interceptor.

*

*

@throws

Throwable

if

the

interceptors

or

the

*

target-object

throws

an

exception.

*/

Object

invoke(MethodInvocation

invocation)

throws

Throwable;

}

類前面的注釋闡明了該辦法的使用，就是要在invoke()辦法中調(diào)用MethodIceed()，將執(zhí)行傳給下一種Interceptor，最后執(zhí)行目的辦法。在proceed()辦法前后加操作，達成Aroudadvice的作用。在Aspect定義好后，就需要在bean定義文獻中進行配備，通過org.springframework.aop.framework.ProxyFactoryBean的配備，指出接口、目的類和Aspect。以下：<bean

id="helloProxy"

class="org.springframework.aop.framework.ProxyFactoryBean">

<!--

業(yè)務(wù)接口

-->

<property

name="proxyInterfaces"

value="spring.advice.IHello"/>

<!--

實現(xiàn)該接口的目的類

-->

<property

name="target"

ref="helloSpeaker"/>

<!--

要應(yīng)用的解釋器，即實現(xiàn)非業(yè)務(wù)操作的Aspect

-->

<property

name="interceptorNames">

<list>

<value>throwAdvice</value>

<!--

還能夠繼續(xù)加,如

<value>logBeforeAdvice</value>

-->

</list>

</property>

</bean>

補充下，其中的目的類、解釋器(Aspect)都要在Bean定義文獻中先進行定義，然后才能夠引用的。我們使用時，代碼以下：IHello

helloProxy=(IHello)context.getBean("helloProxy");

helloProxy.hello();

在Bean定義文獻中配備的Aspect就會在適宜的joinPoint應(yīng)用到目的辦法上。補：IHello接口中有hello()辦法，HelloSpeaker類實現(xiàn)了IHello接口。以免糊涂，給個實例以下，功效是在hello()辦法前后加入日志統(tǒng)計。public

class

AroundAdvice

implements

MethodInterceptor{

private

Logger

logger=

Logger.getLogger(this.getClass().getName());

@Override

public

Object

invoke(MethodInvocation

methodInvocation)

throws

Throwable

{

logger.log(Level.INFO,

"method

starts..."+methodInvocation.getMethod());

Object

result=methodIceed();

logger.log(Level.INFO,"method

ends..."+methodInvocation.getMethod());

return

result;

}

}

配備：<?xml

version="1.0"

encoding="UTF-8"?>

<beans

xmlns="://./schema/beans"

xmlns:xsi="://.//XMLSchema-instance"

xsi:schemaLocation="://./schema/beans

://./schema/beans/spring-beans-3.0.xsd">

<bean

id="helloSpeaker"

class="spring.advice.HelloSpeaker"/>

<bean

id="aroundAdvice"

class="spring.advice.AroundAdvice"/>

<bean

id="helloProxy"

class="org.springframework.aop.framework.ProxyFactoryBean">

<property

name="proxyInterfaces"

value="spring.advice.IHello"

/>

<property

name="target"

r