[ Groovy 常見問題 ] Groovy get current methods annotation

Source From Here 
Question 
I created a java interface for my annotation. I am now writing a class and I would like to print the annotation values so it shows in the log message. Is this possible? Here is my test case and let me know if I am doing this wrong: 

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1. @Retention(RetentionPolicy.RUNTIME)  
2. public @interface TestCase {  
3.     String someID()  
4. }  
5.   
6. class Checkout{  
7.     @TestCase(someID="12345")  
8.     def "a dynamic method name"() {  
9.         // My test steps.....  
10.     }  
11. }  

How-To 
Use StackTraceUtils.sanitize to get the current method and use reflection to iterate through the annotations: 

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1. import java.lang.annotation.Annotation  
2. import java.lang.annotation.Retention  
3. import java.lang.annotation.RetentionPolicy  
4. import java.lang.reflect.Method  
5. import org.codehaus.groovy.runtime.StackTraceUtils  
6.   
7. @Retention(RetentionPolicy.RUNTIME)  
8. public @interface TestCase {  
9.     String someID()  
10. }  
11.   
12. class Checkout{  
13.     @TestCase(someID="12345")  
14.     def "a dynamic method name"() {  
15.         printTestCaseId()  
16.         // My test steps.....  
17.     }  
18.       
19.     def printTestCaseId() {  
20.         def stack = StackTraceUtils.sanitize(new Throwable()).stackTrace[1]  
21.         def method = getClass().declaredMethods.find { it.name == stack.methodName }  
22.         printf("method=${method}\n")  
23.         def someID = method.annotations[0].someID()  
24.         printf("someID=${someID}\n")  
25.         assert someID == "12345"  
26.       }  
27. }  
28.   
29. def co = new Checkout()  
30. co."${'a dynamic method name'}"()  

Execution Result: 

method=public java.lang.Object Checkout.a dynamic method name()
someID=12345

If you want to iterate all methods and corresponding annotations from a class, you can try below sample code: 

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1. import java.lang.annotation.Annotation  
2. import java.lang.annotation.Retention  
3. import java.lang.annotation.RetentionPolicy  
4. import java.lang.reflect.Method  
5.   
6. @Foo('class')  
7. class A{  
8.     def name = "A"  
9.           
10.     @Foo('method')  
11.     def test()  
12.     {  
13.         printf("testing")  
14.     }  
15. }  
16.   
17. A a = new A()  
18. printf("%s\nClass %s\n", a.class.annotations[0], a.class.name)  
19. a.class.declaredMethods.each{ m->  
20.     printf("\tMethod:%s (%d)\n", m.name, m.annotations.size())  
21.     m.getDeclaredAnnotations().each{ an->  
22.         printf("\t\tAnnotation->%s\n", an)  
23.     }  
24.     if(m.isAnnotationPresent(NO.class)) {  
25.         printf("\t\t%s\n", m.getAnnotation(NO.class))  
26.     }  
27. }  

Execution result: 

@Foo(value=class)
Class A
Method:setProperty (0)
Method:getProperty (0)
Method:getName (0)
Method:setName (0)
Method:super$1$hashCode (0)
Method:$getCallSiteArray (0)
Method:$getStaticMetaClass (0)
Method:getMetaClass (0)
Method:__$swapInit (0)
Method:class$ (0)
Method:invokeMethod (0)
Method:super$1$clone (0)
Method:super$1$wait (0)
Method:super$1$wait (0)
Method:super$1$wait (0)
Method:setMetaClass (0)
Method:super$1$notify (0)
Method:super$1$equals (0)
Method:$createCallSiteArray_1 (0)
Method:super$1$toString (0)
Method:super$1$getClass (0)
Method:super$1$notifyAll (0)
Method:$createCallSiteArray (0)
Method:super$1$finalize (0)
Method:test (1)
Annotation->@Foo(value=method)
Method:this$dist$invoke$1 (0)
Method:this$dist$set$1 (0)
Method:this$dist$get$1 (0)

Supplement 
* Documentation - User Guide - Annotations with Groovy 
* Java SE 6 技術手冊 - 第 17 章 Annotation