带注释字段的java Spring AOP切入点表达式

Question

是否可以捕获带有特定注释的任何字段？我的最终目标是向该字段中注入一个值，但目前我的切入点是错误的（不确定语法是否正确）

@Pointcut("execution(* *(..)) && @annotation(com.mycompany.MyAnnotation)")
private void annotatedField(){}

@Around("annotatedField()")
public Object injectValue(final ProceedingJoinPoint proceedingJoinPoint) throws Throwable {}

我相信切入点是用注释说明任何方法。我想把它改成任何领域

Answer 1

我认为你应该遵循Sotirios Delimanolis的建议，尽可能地使用Spring车载方式。如果您仍然认为它们不够充分，并且绝对希望使用方面来实现您的想法，那么您可以使用AspectJ within Spring而不是Spring AOP，并利用get()和set()等切入点的全部功能来拦截类成员（静态和非静态）上的读/写操作。例如：

标记注释：

package de.scrum_master.app;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface MyAnnotation {}

驱动程序应用程序：

应用程序读取（toString()）并写入（构造函数、主方法）所有字段，其中包括带注释的status字段

package de.scrum_master.app;

public class Application {
    private int id;
    private String name;
    @MyAnnotation private String status;

    public Application(int id, String name, String status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    @Override
    public String toString() {
        return "Application [id=" + id + ", name=" + name + ", status=" + status + "]";
    }

    public static void main(String[] args) {
        Application application = new Application(11, "AspectJ demo", "starting");
        System.out.println(application);
        application.id = 22;
        application.name = "AspectJ field access demo";
        application.status = "running";
        System.out.println(application);
        application.status = "shutting down";
        System.out.println(application);
        application.status = "stopped";
        System.out.println(application);
    }
}

方面：

package de.scrum_master.aspect;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

@Aspect
public class AnnotatedFieldAspect {
    @Before("get(* *) && @annotation(de.scrum_master.app.MyAnnotation)")
    public void interceptRead(JoinPoint thisJoinPoint) {
        System.out.println(thisJoinPoint);
    }

    @Before("set(* *) && @annotation(de.scrum_master.app.MyAnnotation) && args(newValue)")
    public void interceptWrite(JoinPoint thisJoinPoint, Object newValue) {
        System.out.println(thisJoinPoint + " -> " + newValue);
    }
}

控制台日志：

set(String de.scrum_master.app.Application.status) -> starting
get(String de.scrum_master.app.Application.status)
Application [id=11, name=AspectJ demo, status=starting]
set(String de.scrum_master.app.Application.status) -> running
get(String de.scrum_master.app.Application.status)
Application [id=22, name=AspectJ field access demo, status=running]
set(String de.scrum_master.app.Application.status) -> shutting down
get(String de.scrum_master.app.Application.status)
Application [id=22, name=AspectJ field access demo, status=shutting down]
set(String de.scrum_master.app.Application.status) -> stopped
get(String de.scrum_master.app.Application.status)
Application [id=22, name=AspectJ field access demo, status=stopped]