之前一論壇朋友問的，復制保存下。 原文地址。

?

問題

貌似不能攔截私有方法？?
試了很多次，都失敗了，是不是不行?。?

我想了一下，因為aop底層是代理，?
jdk是代理接口，私有方法必然不會存在在接口里，所以就不會被攔截到；?
cglib是子類，private的方法照樣不會出現在子類里，也不能被攔截。?

我不是類內部直接調用方法，而是通過維護一個自身實例的代理?

execution(* test.aop.ServiceA.*(..))?

Java代碼??

1. public ? class ?ServiceA?{??
2. ??
3. ???? private ?ServiceA??self;??
4. ??
5. ???? public ? void ?setSelf(ServiceA?self)?{??
6. ???????? this .self?=?self;??
7. ????}??
8. ??
9. ???? public ?String?methodA(String?str)?{??
10. ????????System.out.println( "methodA:?args=" ?+?str);??
11. ????????self.methodB( "b" );??
12. ???????? return ? "12345" ?+?str;??
13. ????}??
14. ??
15. ???? private ?String?methodB(String?str)?{??
16. ????????System.out.println( "methodB:?args=" ?+?str);??
17. ????????self.methodC( "c" );??
18. ???????? return ? "12345" ?+?str;??
19. ????}??
20. ??
21. ???? public ?String?methodC(String?str)?{??
22. ????????System.out.println( "methodC:?args=" ?+?str);??
23. ???????? return ? "12345" ?+?str;??
24. ????}??
25. }??

如果外部調用methodA，那么methodA和methodC會被攔截到，methodB不行?

是不是這么回事？?
但是stackoverflow上，有人說 it works fine?
http://stackoverflow.com/questions/4402009/aspectj-and-catching-private-or-inner-methods?

execution( public ?* test.aop.ServiceA.*(..))?
還有個奇怪的現象，execution里如果不寫權限，那么public protected package的方法都能被攔截到?
如果寫了public，那就只攔截public方法這個沒問題，?
如果寫了protected，他就什么事情都不做，連protected的方法也不攔截。

?

分析

private方法 在Spring使用純Spring AOP（只能攔截public/protected/包）都是無法被攔截的 因為子類無法覆蓋；包級別能被攔截的原因是，如果子類和父類在同一個包中是能覆蓋的。?

在cglib代理情況下， execution(* *(..)) 可以攔截 public/protected/包級別方法（即這些方法都是能代理的）。?

Java代碼??

1. private ? static ? boolean ?isOverridable(Method?method,?Class?targetClass)?{??
2. ???????? if ?(Modifier.isPrivate(method.getModifiers()))?{??
3. ???????????? return ? false ;??
4. ????????}??
5. ???????? if ?(Modifier.isPublic(method.getModifiers())?||?Modifier.isProtected(method.getModifiers()))?{??
6. ???????????? return ? true ;??
7. ????????}??
8. ???????? return ?getPackageName(method.getDeclaringClass()).equals(getPackageName(targetClass));??
9. ????}??

如果想要實現攔截private方法的 可以使用 原生 AspectJ 編譯期/運行期織入。?

原因基本分析明白了：?

是否能應用增強的判斷代碼如下（org.springframework.aop.support.AopUtils）：?

Java代碼??

1. public ? static ? boolean ?canApply(Pointcut?pc,?Class?targetClass,? boolean ?hasIntroductions)?{??
2. ???? if ?(!pc.getClassFilter().matches(targetClass))?{??
3. ???????? return ? false ;??
4. ????}??
5. ??
6. ????MethodMatcher?methodMatcher?=?pc.getMethodMatcher();??
7. ????IntroductionAwareMethodMatcher?introductionAwareMethodMatcher?=? null ;??
8. ???? if ?(methodMatcher? instanceof ?IntroductionAwareMethodMatcher)?{??
9. ????????introductionAwareMethodMatcher?=?(IntroductionAwareMethodMatcher)?methodMatcher;??
10. ????}??
11. ??
12. ????Set?classes?=? new ?HashSet(ClassUtils.getAllInterfacesForClassAsSet(targetClass));??
13. ????classes.add(targetClass);??
14. ???? for ?(Iterator?it?=?classes.iterator();?it.hasNext();)?{??
15. ????????Class?clazz?=?(Class)?it.next();??
16. ????????Method[]?methods?=?clazz.getMethods();??
17. ???????? for ?( int ?j?=? 0 ;?j?<?methods.length;?j++)?{??
18. ???????????? if ?((introductionAwareMethodMatcher?!=? null ?&&??
19. ????????????????????introductionAwareMethodMatcher.matches(methods[j],?targetClass,?hasIntroductions))?||??
20. ????????????????????methodMatcher.matches(methods[j],?targetClass))?{??
21. ???????????????? return ? true ;??
22. ????????????}??
23. ????????}??
24. ????}??
25. ??
26. ???? return ? false ;??
27. }??

此處Method[] methods = clazz.getMethods();只能拿到public方法。。?

場景1：execution(* *(..))?

Java代碼??

1. public ? class ?Impl2??{??
2. ??????
3. ???? protected / public ?String?testAop2()?{??
4. ????????System.out.println( "234" );??
5. ???????? return ? "1233" ;??
6. ????}??
7. }??

因為切入點沒有訪問修飾符，即可以是任意，因此canApply方法能拿到如wait這種public方法，即可以實施代理。?

場景2：execution(public * *(..))?

Java代碼??

1. public ? class ?Impl2??{??
2. ??????
3. ???? public ?String?testAop2()?{??
4. ????????System.out.println( "234" );??
5. ???????? return ? "1233" ;??
6. ????}??
7. }??

因為攔截public的，因此canApply方法能拿到如wait這種public方法，即可以實施代理。?


場景3：execution(protected * *(..))?

Java代碼??

1. public ? class ?Impl2??{??
2. ??????
3. ???? protected ?String?testAop2()?{??
4. ????????System.out.println( "234" );??
5. ???????? return ? "1233" ;??
6. ????}??
7. }??

還記得之前說過，在canApply方法中 的 Method[] methods = clazz.getMethods();只能拿到public方法的，因此跟protected訪問修飾符是無法匹配的，所以如果“execution(protected * *(..))” 是 無法代理的。?

這就是為什么execution(protected * *(..))在純Spring AOP環境下不行的原因。?

注，@Transactional注解事務的特殊情況：?

關于spring切入點語法可以參考我的博客 【 http://jinnianshilongnian.iteye.com/blog/1420691 】

?

?

?

?

是的。?

?

這個只看Cglib2AopProxy吧：?

Java代碼??

1. public ? int ?accept(Method?method)?{??
2. ???????????? if ?(AopUtils.isFinalizeMethod(method))?{??
3. ????????????????logger.debug( "Found?finalize()?method?-?using?NO_OVERRIDE" );??
4. ???????????????? return ?NO_OVERRIDE;??
5. ????????????}??
6. ???????????? if ?(! this .advised.isOpaque()?&&?method.getDeclaringClass().isInterface()?&&??
7. ????????????????????method.getDeclaringClass().isAssignableFrom(Advised. class ))?{??
8. ???????????????? if ?(logger.isDebugEnabled())?{??
9. ????????????????????logger.debug( "Method?is?declared?on?Advised?interface:?" ?+?method);??
10. ????????????????}??
11. ???????????????? return ?DISPATCH_ADVISED;??
12. ????????????}??
13. ???????????? //?We?must?always?proxy?equals,?to?direct?calls?to?this. ??
14. ???????????? if ?(AopUtils.isEqualsMethod(method))?{??
15. ????????????????logger.debug( "Found?'equals'?method:?" ?+?method);??
16. ???????????????? return ?INVOKE_EQUALS;??
17. ????????????}??
18. ???????????? //?We?must?always?calculate?hashCode?based?on?the?proxy. ??
19. ???????????? if ?(AopUtils.isHashCodeMethod(method))?{??
20. ????????????????logger.debug( "Found?'hashCode'?method:?" ?+?method);??
21. ???????????????? return ?INVOKE_HASHCODE;??
22. ????????????}??
23. ????????????Class?targetClass?=? this .advised.getTargetClass();??
24. ???????????? //?Proxy?is?not?yet?available,?but?that?shouldn't?matter. ??
25. ????????????List?chain?=? this .advised.getInterceptorsAndDynamicInterceptionAdvice(method,?targetClass);??
26. ???????????? boolean ?haveAdvice?=?!chain.isEmpty();??
27. ???????????? boolean ?exposeProxy?=? this .advised.isExposeProxy();??
28. ???????????? boolean ?isStatic?=? this .advised.getTargetSource().isStatic();??
29. ???????????? boolean ?isFrozen?=? this .advised.isFrozen();??
30. ???????????? if ?(haveAdvice?||?!isFrozen)?{??
31. ???????????????? //?If?exposing?the?proxy,?then?AOP_PROXY?must?be?used. ??
32. ???????????????? if ?(exposeProxy)?{??
33. ???????????????????? if ?(logger.isDebugEnabled())?{??
34. ????????????????????????logger.debug( "Must?expose?proxy?on?advised?method:?" ?+?method);??
35. ????????????????????}??
36. ???????????????????? return ?AOP_PROXY;??
37. ????????????????}??
38. ????????????????String?key?=?method.toString();??
39. ???????????????? //?Check?to?see?if?we?have?fixed?interceptor?to?serve?this?method. ??
40. ???????????????? //?Else?use?the?AOP_PROXY. ??
41. ???????????????? if ?(isStatic?&&?isFrozen?&&? this .fixedInterceptorMap.containsKey(key))?{??
42. ???????????????????? if ?(logger.isDebugEnabled())?{??
43. ????????????????????????logger.debug( "Method?has?advice?and?optimisations?are?enabled:?" ?+?method);??
44. ????????????????????}??
45. ???????????????????? //?We?know?that?we?are?optimising?so?we?can?use?the ??
46. ???????????????????? //?FixedStaticChainInterceptors. ??
47. ???????????????????? int ?index?=?((Integer)? this .fixedInterceptorMap.get(key)).intValue();??
48. ???????????????????? return ?(index?+? this .fixedInterceptorOffset);??
49. ????????????????}??
50. ???????????????? else ?{??
51. ???????????????????? if ?(logger.isDebugEnabled())?{??
52. ????????????????????????logger.debug( "Unable?to?apply?any?optimisations?to?advised?method:?" ?+?method);??
53. ????????????????????}??
54. ???????????????????? return ?AOP_PROXY;??
55. ????????????????}??
56. ????????????}??
57. ???????????? else ?{??
58. ???????????????? //?See?if?the?return?type?of?the?method?is?outside?the?class?hierarchy ??
59. ???????????????? //?of?the?target?type.?If?so?we?know?it?never?needs?to?have?return?type ??
60. ???????????????? //?massage?and?can?use?a?dispatcher. ??
61. ???????????????? //?If?the?proxy?is?being?exposed,?then?must?use?the?interceptor?the ??
62. ???????????????? //?correct?one?is?already?configured.?If?the?target?is?not?static?cannot ??
63. ???????????????? //?use?a?Dispatcher?because?the?target?can?not?then?be?released. ??
64. ???????????????? if ?(exposeProxy?||?!isStatic)?{??
65. ???????????????????? return ?INVOKE_TARGET;??
66. ????????????????}??
67. ????????????????Class?returnType?=?method.getReturnType();??
68. ???????????????? if ?(targetClass?==?returnType)?{??
69. ???????????????????? if ?(logger.isDebugEnabled())?{??
70. ????????????????????????logger.debug( "Method?" ?+?method?+??
71. ???????????????????????????????? "has?return?type?same?as?target?type?(may?return?this)?-?using?INVOKE_TARGET" );??
72. ????????????????????}??
73. ???????????????????? return ?INVOKE_TARGET;??
74. ????????????????}??
75. ???????????????? else ? if ?(returnType.isPrimitive()?||?!returnType.isAssignableFrom(targetClass))?{??
76. ???????????????????? if ?(logger.isDebugEnabled())?{??
77. ????????????????????????logger.debug( "Method?" ?+?method?+??
78. ???????????????????????????????? "?has?return?type?that?ensures?this?cannot?be?returned-?using?DISPATCH_TARGET" );??
79. ????????????????????}??
80. ???????????????????? return ?DISPATCH_TARGET;??
81. ????????????????}??
82. ???????????????? else ?{??
83. ???????????????????? if ?(logger.isDebugEnabled())?{??
84. ????????????????????????logger.debug( "Method?" ?+?method?+??
85. ???????????????????????????????? "has?return?type?that?is?assignable?from?the?target?type?(may?return?this)?-?" ?+??
86. ???????????????????????????????? "using?INVOKE_TARGET" );??
87. ????????????????????}??
88. ???????????????????? return ?INVOKE_TARGET;??
89. ????????????????}??
90. ????????????}??
91. ????????}??

List chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass); ?
即如果此方法有對應的advice就走代理。?

//getInterceptorsAndDynamicInterceptionAdvice代碼如下所示：?

Java代碼??

1. public ?List?getInterceptorsAndDynamicInterceptionAdvice(Method?method,?Class?targetClass)?{??
2. ????MethodCacheKey?cacheKey?=? new ?MethodCacheKey(method);??
3. ????List?cached?=?(List)? this .methodCache.get(cacheKey);??
4. ???? if ?(cached?==? null )?{??
5. ????????cached?=? this .advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(??
6. ???????????????? this ,?method,?targetClass);? //轉調DefaultAdvisorChainFactory ??
7. ???????? this .methodCache.put(cacheKey,?cached);??
8. ????}??
9. ???? return ?cached;??
10. }??

也就是說需要一次切入點的匹配，即如果方法有切入點就走代理方法 否則目標方法。?


再來看CglibMethodInvocation（cglib的 DynamicAdvisedInterceptor使用）：?

?

即如果有InterceptorAndDynamicMethodMatcher 這是動態切入點切入點匹配器：?

引用spring文檔?

?

這個在spring aop中只有一種情況：PerTargetInstantiationModelPointcut 這個切入點；這個可以參考《 【第六章】 AOP 之 6.8 切面實例化模型 ——跟我學spring3? 》 pertarget。?

也就是說如果是?
靜態切入點代理：如果有匹配的advice就走代理；?
動態切入點代理：需要在運行時進行匹配。?


綜上所述：?
execution(* *(..)) 可以匹配public/protected的，因為public的有匹配的了，目標類就代理了，，，再進行切入點匹配時也是能匹配的，而且cglib方式能拿到包級別/protected方法，而且包級別/protected方法可以直接通過反射調用。?

?

這個是因為protected 修飾符的切入點 無法匹配 Method[] methods = clazz.getMethods(); 這里的任何一個，因此無法代理的。?