java - 如何使用 SpEL 设置注释字段来处理值

Question

我需要在带注释的接口(interface)中设置一些字段以接受 Spring 表达式语言定义。

我有一个工作代码，但我对此不满意。请参阅:

注释:

@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
public @interface Example {
    String id();
}

方面:

@Aspect
@Component
public class ExampleAspect {
    @Before("@annotation(com.example.annotation.Example)")
    public void beforeAdvice(JoinPoint joinPoint) {

        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Example p = signature.getMethod().getAnnotation(Example.class);
        long id = (Long) valueFromExpression(joinPoint, p.id());
        // .... work with ID
    }

    /**
     * Manually processed SpEL expression
     */
    private Object valueFromExpression(JoinPoint joinPoint, String expression) {
        ExpressionParser parser = new SpelExpressionParser();

        StandardEvaluationContext context = new StandardEvaluationContext();
        CodeSignature codeSignature = (CodeSignature) joinPoint.getSignature();
        String[] parameterNames = codeSignature.getParameterNames();
        Object[] args = joinPoint.getArgs();

        for (int i = 0; i < parameterNames.length; i++) {
            context.setVariable(parameterNames[i], args[i]);
        }

        Expression exp = parser.parseExpression(expression);

        return exp.getValue(context);
    }
}

用法:

@GetMapping("/test/{someId}")
@Example(id = "#someId")
public void example(@PathVariable Long someId) {
   // some code
}

这可行，但我想将注释属性的初始化定义为由 SpEL 自动处理，并由我的 IDE 正确突出显示 - 没有方法 valueFromExpression()

Answer 1

关于 IDE 支持，请参阅 [@StéphaneNic​​oll] 的回答:https://stackoverflow.com/a/33298418/3759414

"The support in Intellij is the same thing. Currently Jetbrains devs track the places where SpEL is used and mark them for SpEL support. We don't have any way to conduct the fact that the value is an actual SpEL expression (this is a raw java.lang.String on the annotation type after all)."