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This article is about how to achieve @ Aspect weaving that does not take effect and does not perform pre-enhanced weaving @ Before in SpringAop. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

SpringAop @ Aspect weaving does not work, do not perform pre-enhanced weaving @ Before want to write an AOP, there are two main purposes

The first intention is to do back-end token validation to prevent form repeated submissions.

The second intention is to unify the verification results of the background JSR303 Validator, and do not want to distribute the processing of the verification results in each controller method.

@ ResponseBody @ RequestMapping (value = "add", method = RequestMethod.POST) public ResponseModel add (@ Valid User user, BindingResult br, HttpServletResponse response) {if (br.hasErrors ()) {return ResponseModel.validFail (getErrorsSplitNewLine (br));} accountService.addUser (user) Return ResponseModel.success ("Save user success");}

As in the above method, br.hasErrors () exists in each form submission method, and you want to extract it separately and use AOP unified processing.

So write an AOP, as follows:

@ Aspect@Componentpublic class ParamValidAspect {@ Before ("@ annotation (com.hebao.tech.adm.framework.annotation.ParamValid)") public void paramValid (JoinPoint point) {System.out.println ("Parameter checking cut-in method was called."); / / omitted}}

Since the main purpose of this article is to record the reasons why AOP does not take effect, I will not write about the specific implementation here.

The above defines an Aop weave on the annotated Controller method with the annotation @ ParamValid.

Import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target; @ Target (ElementType.METHOD) @ Retention (RetentionPolicy.RUNTIME) public @ interface ParamValid {}

The content of this ParamValid is just an iconic comment, declared as a method-level comment, and a run-time comment.

Finally, add the AOP dynamic proxy setting to application.xml.

If the spring configuration file has not introduced the configuration of aop, you also need to add the xml declaration

Finished, tested, found a little tragic, the basic weaving does not take effect, does not report an error, Leng is not to execute the relevant weaving code.

Finally, I searched the Internet and found that Spring and SpringMVC are two different parent-child containers. @ Aspect is loaded by the spring container, while the instantiation and injection of these classes annotated by @ Controller is done by SpringMVC. If @ Aspect is loaded by the spring container, the Spring MVC container may not have been initialized and the Controller class has not been initialized, so it cannot be woven properly.

So the adjustment is as follows:

@ Aspectpublic class ParamValidAspect {@ Before ("@ annotation (com.hebao.tech.adm.framework.annotation.ParamValid)") public void paramValid (JoinPoint point) {System.out.println ("Parameter checking cut-in method was called."); / / omitted}}

Remove the @ Component annotation, then move aop:aspectj-autoproxy to the springmvc configuration file, and define bean, as follows:

In this way, we are done.

Using @ Aspect,@Before is not called @ Aspect@Componentpublic class LogAspect {@ Before ("pointcut ()") public void before () {System.out.println ("before");} @ Pointcut ("@ annotation (com.demo.annotation.Log)") public void pointcut () {} @ Around ("pointcut ()") public void around () {System.out.println ("arount") @ After ("pointcut ()") public void after () {System.out.println ("after");}}

Call the method to return the result:

Arount

After

@ Aspect@Componentpublic class LogAspect {@ Before ("pointcut ()") public void before () {System.out.println ("before");} @ Pointcut ("@ annotation (com.mxy.annotation.Log)") public void pointcut () {} @ Around ("pointcut ()") public void around (ProceedingJoinPoint point) {System.out.println ("arount before") Try {point.proceed ();} catch (Throwable throwable) {throwable.printStackTrace ();} System.out.println ("arount after");} @ After ("pointcut ()") public void after () {System.out.println ("after");}}

The call returns the result:

Arount before

Before

Arount after

After

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