英文:
Dynamically creating object instance of interface / abstract class
问题
In Groovy or Java, 假设我有一个带有一些未实现方法的接口（或抽象类）。 我想在运行时动态生成该接口/抽象类的实例，并为这些未实现的方法提供一些行为（例如，基于这些方法上的注解）。
即，类似于
interface Foo {@SomeAnnotation(...)foo();}
Foo foo = someMagic(Foo.class, somethingToProvideLogicOfUnimplementedMethods);
是否有任何库或技术可以实现这一目标？
英文:
In Groovy or Java, assume I have an interface (or abstract class) with some unimplemented methods. I would like to generate an instance of this interface/abstract class dynamically in runtime, and have some behaviour for those unimplemented methods (e.g. based on annotation on those methods)
i.e. something like
interface Foo {@SomeAnnotation(...)foo();}
Foo foo = someMagic(Foo.class, somethingToProvideLogicOfUnimplementedMethods);
Are there any library or technique that can achieve this?
答案1
得分: 4
在Groovy中，以下的魔法被称为“Map to Interface coercion”，并且可以直接使用：
import static java.lang.annotation.ElementType.METHODimport static java.lang.annotation.RetentionPolicy.RUNTIMEimport java.lang.annotation.Retentionimport java.lang.annotation.Target@Retention( RUNTIME )@Target( [ METHOD ] )@interface Some {String value() default ''}interface Foo {@Some( 'AWESOME' )void foo()}Foo magicFoo = [ foo:{->String annotationValue = Foo.methods.first().annotations.first().value()println "the $annotationValue MAGIC printed!"} ] as Fooassert Foo.isAssignableFrom( magicFoo.getClass() )magicFoo.foo()
在控制台中输出：
the AWESOME MAGIC printed!
英文:
In Groovy the following magic is called "Map to Interface coercion" and is available out of the box:
import static java.lang.annotation.ElementType.METHODimport static java.lang.annotation.RetentionPolicy.RUNTIMEimport java.lang.annotation.Retentionimport java.lang.annotation.Target@Retention( RUNTIME )@Target( [ METHOD ] )@interface Some {String value() default ''}interface Foo {@Some( 'AWESOME' )void foo()}Foo magicFoo = [ foo:{->String annotationValue = Foo.methods.first().annotations.first().value()println "the $annotationValue MAGIC printed!"} ] as Fooassert Foo.isAssignableFrom( magicFoo.getClass() )magicFoo.foo()
prints in the console:
the AWESOME MAGIC printed!
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