Class.getEnclosingClass 和 Class.getDeclaringClass

曾经终败给现在 2022-02-04 03:06 155阅读 0赞

1、getDeclaringClass  
  return the declaring class for this class  
  获取对应类的声明类Class对象  
2、getEnclosingClass  
  return the immediately enclosing class of the underlying class  
  (获取对应类的直接外部类Class对象)

区别：  
两者的区别在于匿名内部类的使用上、getEnclosingClass能够获取匿名内部类对应的外部类Class对象，而getDeclaringClass不能够获取匿名内部类对应的声明类Class对象。

代码示例:

/**
     * @author <a href="wangte@meitaun.com">Te</a>
     * @date created at 2019/5/6
     */
    public class ClassTest {
    
        /**
         * 1、Class.GetEnclosingClass
         * <doc>获取对应类的直接外部类Class对象</doc>
         * 2、Class.GetDeclaringClass
         * <doc>获取对应类的声明类Class对象</doc>
         * 3、两者的区别
         * <p>
         * GetEnclosingClass与GetDeclaringClass很相近
         * 两者的区别在于匿名内部类、getEnclosingClass对匿名内部类也有效
         */
        public static void main(String[] args) {
            Class<?> enclosingClass = InnerClass.class.getEnclosingClass();
            System.out.println(enclosingClass.getName());
    
            Class<?> declaringClass = InnerClass.class.getDeclaringClass();
            System.out.println(declaringClass.getName());
    
            //注意：GetEnclosingClass获取的是直接定义该类的外部类Class实例、这点和getDeclaringClass一致
            Class<?> enclosingClass1 = InnerClass.InnerInnerClass.class.getEnclosingClass();
            System.out.println(enclosingClass1.getName());
    
            Class<?> declaringClass1 = InnerClass.InnerInnerClass.class.getDeclaringClass();
            System.out.println(declaringClass1.getName());
    
            //针对匿名内部类的测试
            DifferentBetweenClassGetEnclosingClassAndDeclaringClass s = new DifferentBetweenClassGetEnclosingClassAndDeclaringClass();
            HelloService inst = s.getHelloService();
            inst.sayHello();
        }
    
        private class InnerClass {
    
            private class InnerInnerClass {
    
            }
        }
    
    
        public interface HelloService {
    
            void sayHello();
        }
    
    
        public static class DifferentBetweenClassGetEnclosingClassAndDeclaringClass {
    
            HelloService getHelloService() {
                //匿名内部类
                return new HelloService() {
    
                    @Override
                    public void sayHello() {
                        System.out.println(this.getClass().getEnclosingClass());
    
                        System.out.println(this.getClass().getDeclaringClass());
    
                    }
    
                };
            }
    
        }
    }