On AspectJ framework

Catalog

AspectJ frame

AspectJ Common notification types

AspectJ The pointcut expression of ( master )

AspectJ Prior notice of @Before

Implementation of pre notification annotation

  Pre notification mode parameters jionpoint analysis

AspectJ Frame switching JDK Dynamic proxy sum CGLib A dynamic proxy

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AspectJ frame

 AspectJ It's a faceted framework , He defined AOP Some of the syntax , There is a special bytecode generator to generate compliance java canonical class file .

 AspectJ The notification types of include not only the four kinds of notifications we have learned before ： Pre notice 、 The rear notice 、 Surround notification and exception notification , And there is one more Final notice That is, whether the program is normally executed , The code of the final notification will be executed .

The reason is that Pointcut expression , Pointcut expressions can Identify which classes and methods the facet is woven into , Just Unwanted Like we used before spring Realization AOP like that A variety of configurations . As long as the implementation of the section is configured , Then write the pointcut expression .

AspectJ Common notification types

  AspectJ There are four types of notifications commonly used in ：

  1) Pre notice @Before
  2) The rear notice @AfterReturning
  3) Surrounding the notification @Around
  4) Final notice @After
  5) Defining entry points @Pointcut( understand )

AspectJ The pointcut expression of ( master )

  Canonical formula :
  execution( Access right Method return value Method statement ( Parameters ) Exception types )
  The simplified formula :
  execution( Method return value Method statement ( Parameters ) )

  The symbols used :
  *   Code any arbitrary character ( wildcard )
  ..   If it appears in the parameter of the method , Represents any parameter
      If it appears in the path , Represents this path and all its sub paths

  Example :
  execution(public * *(..)) : Any public method
  execution(* set*(..)): Any one of them “set” The way to start
  execution(* com.xyz.service.impl.*.*(..)): Any return value type , stay com.xyz.service.impl Any parameter of any method of any class under the package
  execution(* com.xyz.service..*.*(..)): Any return value type , stay com.xyz.service And any parameter of any method of any class under its subpackage  
                                           com.xyz.service.a.b.*.*(..)  com.xyz.service.*.*(..)
  execution(* *..service.*.*(..)):service There can be any sub package before
  execution(* *.service.*.*(..)):service There was only one bag before

AspectJ Prior notice of @Before

  Cut into the facet function before the execution of the target method . The return value of the target method cannot be obtained in the facet method , Only the signature of the target method can be obtained .

  Implementation steps :
  Add dependency
   <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aspects</artifactId>
      <version>5.2.5.RELEASE</version> 
    </dependency>
  1) Creating a business interface
  2) Create a business implementation
  3) Create the section class , Implementation of section method
  4) stay applicationContext.xml File for slice binding

 

  Project case :
  @Aspect  // hand AspectJ Framework to identify facet classes
@Component
public class MyAspect {
    /**
     * All facet functions are realized by facet method
     * Various aspects can be developed in this class
     *
     * Specification of aspect method of pre notification
     * 1) Access rights are public
     * 2) The return value of the void
     * 3) Method name customization
     * 4) Method has no parameters , If so, it can only be JoinPoint type
     * 5) You have to use @Before Annotation to declare that the timing of entry is the pre cutting function and entry point
     *   Parameters :value   Specify pointcut expression
     *
     * Business methods
     * public String doSome(String name, int age)
     */
    @Before(value = "execution(public String com.bjpowernode.s01.SomeServiceImpl.*(String,int))")
    public void myBefore(){
        System.out.println(" Implementation of pre notification function in aspect method ............");
    }

    @Before(value = "execution(public * com.bjpowernode.s01.SomeServiceImpl.*(..))")
    public void myBefore(){
        System.out.println(" Implementation of pre notification function in aspect method ............");
    }

    @Before(value = "execution( * com.bjpowernode.s01.*.*(..))")
    public void myBefore(JoinPoint jp){
        System.out.println(" Implementation of pre notification function in aspect method ............");
        System.out.println(" Signature of the target method :"+jp.getSignature());
        System.out.println(" Parameters of the target method :"+ Arrays.toString(jp.getArgs()));
    }
    @Before(value = "execution( * com.bjpowernode.s01..*(..))")
    public void myBefore(){
        System.out.println(" Implementation of pre notification function in aspect method ............");
    }

    @Before(value = "execution( * *(..))")
    public void myBefore(){
        System.out.println(" Implementation of pre notification function in aspect method ............");
    }
}

Implementation of pre notification annotation

 

  Pre notification mode parameters jionpoint analysis

 

 

AspectJ Frame switching JDK Dynamic proxy sum CGLib A dynamic proxy

 

    <aop:aspectj-autoproxy ></aop:aspectj-autoproxy>  ===> The default is JDK A dynamic proxy , Interface type must be used when fetching 

    <aop:aspectj-autoproxy proxy-target-class="true"></aop:aspectj-autoproxy>  ==> Set to CGLib Subclass proxy , You can use interfaces and implementation classes 

    remember : Use the interface to connect , Never make mistakes .