spring4中文技术手册==.docx

spring4中文技术手册在静态代理和动态代理中提到了面向方面编程，主要就是基于动态代理。单独抽象出非业务的功能，服务于某些业务方法。Spring提供了四种很实用的Advice，分别为：Before Advice, After Returning Advice, Around Advice, After throwing Advice。都是方法级别的，就是在某个方法执行前后插入一些非业务的操作，如打日志或者判断权限等。对于这四种advice的实现，spring都提供了三种方法，分别为基于接口、基于xml和基于annotation(注释)。Before Advice会在目标对象的方法执行之前被调用；After Advice会在目标方法执行之后被调用；Around Advice则可以在目标方法执行前后同时加上相关服务；Throw Advice是在异常发生后执行某些操作。1.基于接口的Advice这个就需要自定义的Aspect实现Spring接口。BeforeAdvice需要实现org.springframework.aop.MethodBeforeAdvice接口：1. /*2. *Adviceinvokedbeforeamethodisinvoked.Suchadvicescannot3. *preventthemethodcallproceeding,unlesstheythrowaThrowable.4. */5. publicinterfaceMethodBeforeAdviceextendsBeforeAdvice6. 7. /*8. *Callbackbeforeagivenmethodisinvoked.9. *parammethodmethodbeinginvoked10. *paramargsargumentstothemethod11. *paramtargettargetofthemethodinvocation.Maybenull.12. *throwsThrowableifthisobjectwishestoabortthecall.13. *Anyexceptionthrownwillbereturnedtothecallerifits14. *allowedbythemethodsignature.Otherwisetheexception15. *willbewrappedasaruntimeexception.16. */17. voidbefore(Methodmethod,Objectargs,Objecttarget)throwsThrowable;18. After Advice实现org.springframework.aop.AfterReturningAdvice接口：1. /*2. *Afterreturningadviceisinvokedonlyonnormalmethodreturn,notifan3. *exceptionisthrown.Suchadvicecanseethereturnvalue,butcannotchangeit.4. */5. publicinterfaceAfterReturningAdviceextendsAfterAdvice6. /*7. *Callbackafteragivenmethodsuccessfullyreturned.8. *paramreturnValuethevaluereturnedbythemethod,ifany9. *parammethodmethodbeinginvoked10. *paramargsargumentstothemethod11. *paramtargettargetofthemethodinvocation.Maybenull.12. *throwsThrowableifthisobjectwishestoabortthecall.13. *Anyexceptionthrownwillbereturnedtothecallerifits14. *allowedbythemethodsignature.Otherwisetheexception15. *willbewrappedasaruntimeexception.16. */17. voidafterReturning(ObjectreturnValue,Methodmethod,Objectargs,Objecttarget)throwsThrowable;18. Around Advice需要实现ercept.MethodInterceptor接口：1. /*2. *Theusershouldimplementthelink#invoke(MethodInvocation)3. *methodtomodifytheoriginalbehavior.E.g.thefollowingclass4. *implementsatracinginterceptor(tracesallthecallsonthe5. *interceptedmethod(s):6. *7. *8. *classTracingInterceptorimplementsMethodInterceptor9. *Objectinvoke(MethodInvocationi)throwsThrowable10. *System.out.println(method+i.getMethod()+iscalledon+11. *i.getThis()+withargs+i.getArguments();12. *Objectret=ceed();13. *System.out.println(method+i.getMethod()+returns+ret);14. *returnret;15. *16. *17. */18. publicinterfaceMethodInterceptorextendsInterceptor19. 20. /*21. *Implementthismethodtoperformextratreatmentsbeforeand22. *aftertheinvocation.Politeimplementationswouldcertainly23. *liketoinvokelinkJoinpoint#proceed().24. *25. *paraminvocationthemethodinvocationjoinpoint26. *returntheresultofthecalltolink27. *Joinpoint#proceed(),mightbeinterceptedbythe28. *interceptor.29. *30. *throwsThrowableiftheinterceptorsorthe31. *target-objectthrowsanexception.*/32. Objectinvoke(MethodInvocationinvocation)throwsThrowable;33. 类前面的注释说明了该方法的使用，就是要在invoke()方法中调用MethodIceed()，将执行传给下一个Interceptor，最终执行目标方法。在proceed()方法前后加操作，到达Aroud advice的作用。在Aspect定义好后，就需要在bean定义文件中进行配置，通过org.springframework.aop.framework.ProxyFactoryBean的配置，指出接口、目标类和Aspect。如下：1. 2. 3. 4. 5. 6. 7. 8. 9. throwAdvice10. !-还可以继续加,如11. logBeforeAdvice-12. 13. 14. 补充下，其中的目标类、解释器(Aspect)都要在Bean定义文件中先进行定义，然后才可以引用的。我们使用时，代码如下：1. IHellohelloProxy=(IHello)context.getBean(helloProxy);2. helloProxy.hello();在Bean定义文件中配置的Aspect就会在合适的joinPoint应用到目标方法上。补：IHello接口中有hello()方法，HelloSpeaker类实现了IHello接口。以免糊涂，给个实例如下，功能是在hello()方法前后加入日志记录。1. publicclassAroundAdviceimplementsMethodInterceptor2. privateLoggerlogger=3. Logger.getLogger(this.getClass().getName();4. Override5. publicObjectinvoke(MethodInvocationmethodInvocation)throwsThrowable6. 7. logger.log(Level.INFO,methodstarts.+methodInvocation.getMethod();8. Objectresult=methodIceed();9. logger.log(Level.INFO,methodends.+metho