Java Field getAnnotatedType()方法及示例

java.lang.reflect.Field 的 getAnnotatedType() 方法用于返回一个annonatedType对象，该对象表示使用一个类型来指定该字段的声明类型。类的每个字段都是由一些AnnotatedType声明的。AnnotatedType代表任何类型的潜在注释使用，包括数组类型、参数化类型、类型变量或当前在Java虚拟机中运行的通配符类型。返回的 AnnotatedType 实例可以是 AnnotatedType 本身的实现或其子接口之一的实现。AnnotatedArrayType、AnnotatedParameterizedType、AnnotatedTypeVariable、AnnotatedWildcardType。

语法

public AnnotatedType getAnnotatedType()

参数： 该方法不接受任何东西。
返回 ：该方法返回一个代表该字段所代表的声明类型的 对象 。下面的程序说明了getAnnotatedType()方法。

程序1 :

// Java program to illustrate
// getAnnotatedType() method
 
import java.lang.reflect.AnnotatedType;
import java.lang.reflect.Field;
import java.util.Arrays;
 
public class GFG {
 
    private int number;
 
    public static void main(String[] args)
        throws NoSuchFieldException
    {
 
        // get Field object
        Field field
            = GFG.class
                  .getDeclaredField("number");
 
        // apply getAnnotatedType() method
        AnnotatedType annotatedType
            = field.getAnnotatedType();
 
        // print the results
        System.out.println(
            "Type: "
            + annotatedType
                  .getType()
                  .getTypeName());
        System.out.println(
            "Annotations: "
            + Arrays
                  .toString(
                      annotatedType
                          .getAnnotations()));
    }
}

输出

Type: int
Annotations: []

程序2

// Java Program to illustrate
// getAnnotatedType() method
 
import java.lang.annotation.*;
import java.lang.reflect.*;
import java.util.Arrays;
 
public class GFG {
 
    private int @SpecialNumber[] number;
 
    public static void main(String[] args)
        throws NoSuchFieldException
    {
        // get Field object
        Field field
            = GFG.class
                  .getDeclaredField("number");
 
        // apply getAnnotatedType() method
        AnnotatedType annotatedType
            = field.getAnnotatedType();
 
        // print the results
        System.out.println(
            "Type: "
            + annotatedType
                  .getType()
                  .getTypeName());
        System.out.println(
            "Annotations: "
            + Arrays
                  .toString(
                      annotatedType
                          .getAnnotations()));
        System.out.println(
            "Declared Annotations: "
            + Arrays
                  .toString(
                      annotatedType
                          .getDeclaredAnnotations()));
    }
 
    @Target({ ElementType.TYPE_USE })
    @Retention(RetentionPolicy.RUNTIME)
    private @interface SpecialNumber {
    }
}

输出

Type: int[]
Annotations: [@GFGSpecialNumber()]
Declared Annotations: [@GFGSpecialNumber()]

参考文献 ： https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/Field.html#getAnnotatedType-