Java Constructor getDeclaredAnnotations()方法

java.lang.reflect.Constructor.getDeclaredAnnotations()方法返回此元素上直接存在的所有注释。与此接口中的其他方法不同，此方法忽略了继承的注释(如果此元素上没有注释，则返回长度为零的数组)。此方法的调用者可以自由修改返回的数组; 它将对返回给其他调用者的数组没有影响。

1 语法

public Annotation[] getDeclaredAnnotations()

2 参数

无

3 返回值

返回在此元素上所有注释。

4 示例 

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java Constructor getDeclaredAnnotations()方法
 */
import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.reflect.Constructor;

public class ConstructorDemo {
   public static void main(String[] args) {
      Constructor[] constructors = SampleClass.class.getConstructors();
      Annotation[] annotations = constructors[0].getDeclaredAnnotations();
      for(Annotation annotation : annotations){
         if(annotation instanceof CustomAnnotation){
            CustomAnnotation customAnnotation = (CustomAnnotation) annotation;
            System.out.println("name: " + customAnnotation.name());
            System.out.println("value: " + customAnnotation.value());
         }
      }
   }
}

@CustomAnnotation(name="SampleClass",  value = "Sample Class Annotation")
class SampleClass {
   private String sampleField;

   @CustomAnnotation(name="sampleClassConstructor",  value = "Sample Constructor Annotation")
   public SampleClass(){
   }

   public SampleClass(String sampleField){
      this.sampleField = sampleField;
   }

   public String getSampleField() {
      return sampleField;
   }

   public void setSampleField(String sampleField) {
      this.sampleField = sampleField;
   } 
}

@Retention(RetentionPolicy.RUNTIME)
@interface CustomAnnotation {
   public String name();
   public String value();
}

输出结果为：

name: sampleClassConstructor
value: Sample Constructor Annotation