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Spring实战 (四) AOP

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在软件开发中,分布于应用多出的功能被称为和横切关注点 . 通常,这些横切关注点从概念上是与应用的业务逻辑相分离的(但是往往直接嵌入到应用的业务逻辑中).将这些横切关注点与业务逻辑相分离正是面向切面编成 (AOP)所要解决的要了解什么是AOP,首先应该了解AOP相关术语,只有完全理解这些,才能更好的掌握AOP 描述切面的常用术语有通知(advice), 切点(pointcut), 连接点(join point). 通知(advice) 切面有目标－他必须要完成的工作,成为通知.通知定义了切面是什么以及何时使用. Spring切面可以应用5种类型的通知 Before 在方法被调用之前调用通知 After 在方法完成之后调用通知,无论方法执行是否成功 After-returning 在方法成功执行之后调用通知 After-throwing 在方法抛出异常后调用通知 Around 通知包裹了被通知的方法,在被通知的方法调用之前和调用之后执行自定义的行为连接点(join point) 连接点是在应用执行过程中能够插入切面的一个点.这个点可以是调用方法时,抛出异常时,甚至修改一个字段时.切面代码可以利用这些点插入到应用的正常流程之中,并添加新的行为切点(pointcut) 切点的定义会匹配通知所要织入的一个或多个连接点切面(Aspect) 切面是通知和切点的结合

Why tomcat throw NullPointException when I use pointcut for args()?

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问题 I try to use AspectJ pointcut for args(), but run in springboot with tomcat it threws NullPointException. Since it reported a null pointer exception, and I debugged it when the variable logger of the GenericFilterBean variable is null, I don't know if I need to add extra configuration or what? I would be grateful if anyone knows how to solve this problem. error log : 2018-11-26 11:07:22.952 ERROR 12620 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Exception starting filter

Enabling compile-time AspecJ for Spring Method Security

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问题 Spring AOP runs everything through proxies which sadly can't be everywhere. For this reason Spring Security's annotations @PreAuthorize , @PostAuthorize , @PreFilter and @PostFilter (also @Secured ) will not be taken into consideration when calls are not going through said proxies. Proxies are created only for singletons ( @Bean s) so We are greatly limited when We want to secure methods on specific objects (such as JPA @Entities ) that are not beans. Proxies also won't be called within

Scale image inside div up AND/OR down to fit largest side of image with CSS

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问题 I've looked through A LOT of Q&A here on the topic but can't find a definitive answer if one exists. I have a div of dynamic width and height and want to fit any sized image inside of it and keep the aspect ratio. This could be scaling the image up or down: I've tried every combo of width, height, max-width, max-height, Object-fit etc I can think of with no luck, there's always at least one case that fails. Most solutions I've seen involve some hard coded max-width or height values. Is it

Can AspectJ weave through sun.net.* packages?

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问题 I'm using AspectJ to intercept java.net.Socket calls. I've created very simple aspect after(): call(* java.net.Socket.connect(..)) { System.out.println("Connect intercepted!"); } and aop.xml <aspectj> <aspects> <aspect name="com.iggroup.lightstreamer.nwtp.SocketExceptionLoggingAspect"/> </aspects> <weaver options="-Xlint:ignore -Xset:weaveJavaxPackages=true -Xset:weaveJavaPackages=true"> </weaver> </aspectj> When the call stack is like this, then I can see the console output: java.lang

Can AspectJ weave through sun.net.* packages?

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AspectJ - parse definitions failed - NullPointerException

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问题 Here's MVCE https://github.com/yami12376/AspectJ Add VM arguments to Run/Debug configuration of Junit test , in my case: -javaagent:C:\aspectjWeaver\spring-instrument-3.0.4.jar -javaagent:C:\aspectjWeaver\aspectjweaver-1.6.11.jar In my case i added this in JAVA build path : \target\classes\META-INF from src/main/resources Run Junit test If you delete aop.xml it's still weaving type org.* but on the other hand aop.xml should not weave it beacuse it has: <include within="com.*"/> Why does it

BeanNameAutoProxyCreator setBeanNames regular expression not working?

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问题 This is my BeanNameAutoProxyCreator : @Bean public BeanNameAutoProxyCreator beanNameAutoProxyCreator() { BeanNameAutoProxyCreator beanNameAutoProxyCreator = new BeanNameAutoProxyCreator(); beanNameAutoProxyCreator.setBeanNames("*service"); // If i put "*Service" instead, then i get an exception. beanNameAutoProxyCreator.setInterceptorNames("loggingAdvice", "debugInterceptor"); return beanNameAutoProxyCreator; } @Bean public LoggingAdvice loggingAdvice() { return new LoggingAdvice(); } @Bean

How to start aspectj loadtime weaver agent without restarting jvm / how to start loadtime weaver in code?

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问题 Is there any way to start the AspectJ loadtime weaver during the application is running? Means without restarting the JVM and adding -javaagent:... ? I tried https://stackoverflow.com/a/35775792/3880225 but without any success. 回答1: Yes, you can do that, I implemented this capability myself for AspectJ and it was included since version 1.8.7, see release notes for an example. But please note that weaving will only work for classes loaded after you have activated the weaver. 来源： https:/

Spring @Transactional wont rollback after putting aspect around method

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问题 I have two transactional methods one inside other. When around aspect is not set around methodA Transactional anotation work well. After calling methodA we call methodB, methodB write something in DB, then we return in methodA, throw an exception and then methodB roolback. But when I put my aspect around methodA, methodB wont rollback. I cant figure out what is happening there. I tried many combination of propagation attributes but none seems to work. Thanks in advance. I use Spring 2.5.4 I