Groovy:如何调用带注释的方法 [英] Groovy: How to call annotated methods

问题描述

在几个此类的某些方法的顶部，我有一个注释@MyAnnotation:

I have an annotation @MyAnnotation sticked on the top of some methods in a couple of classes like these:

FirstClass {
    @MyAnnotation
    doSomethingWith(String text) { println 'text from first class' }

    @MyAnnotation
    doSomethingWith(Foo foo) { println 'foo from first class' }

    @MyAnnotation
    doAlsoSomethingWith(Bar bar) { println 'bar from first class' }    
}

SecondClass {
    @MyAnnotation
    doOtherStuffWith(Foo foo) { println 'foo from second class' }    
}

GenericGateway {    
    execute(instancedParam) {
        // call something passing an instance of "Foo" class
        // call something passing an instance of "Bar" class
        // call something passing an instance of "String" class
    }   
}

现在，我希望每个带有@MyAnnotation注释和相同方法参数(而不关心方法名称自身)的方法都将在运行时基于实例参数从网关"中调用.

Now I am expecting that every method annotated with @MyAnnotation and same method's arguments (not caring of the method's name self) it is called at runtime from the "gateway" based on the instanced parameter.

// Example:

gateway.execute(new Foo(...))
gateway.execute('something')
gateway.execute(new Bar(...))

// I am expecting to see:

foo from first class
foo from second class
text from first class
bar from first class

如果我要用Java解决它，我可能最终会使用反射" API并通过某种策略将方法名称映射到某个地方.有没有办法用Groovy更优雅"地做到这一点?

If I am going to solve it with Java I will probably end up to use "reflection" API and mapping the method names somewhere with some strategy. Is there a way to do it more "elegantly" with Groovy?

推荐答案

我不知道任何简化Java反射API的捷径.但是您总是可以从Groovy的简洁中受益:

I'm not aware of any shortcut to ease Java's reflection API. But you can always benefit from Groovy's terseness:

import java.lang.reflection.*
import java.lang.annotation.*

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@interface A {}

class Annotated {
  @A def a() { "a" }
  @A def b() { "b" }
  def c() { "c" }
}

ann = new Annotated()

methods = ann.class.methods.findAll { it.getAnnotation(A) }

assert methods.size() == 2

assert methods.collect { it.invoke(ann) } == ["a", "b"]

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