java注解练习

题目：
1.创建Apple.java类，编写属性appleColor,appleName,provider。
2.创建3个自定义属性注解类@FruitColor，@FruitName，@FruitProvider，运行周期为运行时。
3.分别为Apple的3个属性设置属性注解。
4.提取Apple类的注解信息。

package teacher.day09;

import java.lang.annotation.*;
import java.lang.reflect.Field;

public class Apple {

    @FruitColor()
    private String appleColor;

    @FruitName(value = "新疆小苹果")
    private String appleName;

    @FruitProvider(value = "新疆")
    private String provider;

}

class Teset06 {
    public static void main(String[] args) {

        Class clazz = Apple.class;

        Field[] declaredFields = clazz.getDeclaredFields();

        //字段
        for (Field declaredField : declaredFields) {

            //该类中所有的注解
            Annotation[] declaredAnnotations = declaredField.getDeclaredAnnotations();
            System.out.println("字段名 = " + declaredField.getName());
            //字段上面的注解
            for (Annotation declaredAnnotation : declaredAnnotations) {
                if (declaredAnnotation instanceof FruitColor) {
                    FruitColor fruitColor = (FruitColor) declaredAnnotation;
                    System.out.println("fruitColor注解值 = " + fruitColor.value());
                } else if (declaredAnnotation instanceof FruitName) {
                    FruitName fruitName = (FruitName) declaredAnnotation;
                    System.out.println("fruitName注解值 = " + fruitName.value()+"===>"+fruitName.fruitName());
                } else if (declaredAnnotation instanceof FruitProvider) {
                    FruitProvider fruitProvider = (FruitProvider) declaredAnnotation;
                    System.out.println("fruitProvider注解值 = " + fruitProvider.value());
                }
            }
        }
    }
}

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface FruitColor {

    String value() default "红色";

}

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface FruitName {

    String value() default "红富士";
    String fruitName() default "红苹果";

}

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface FruitProvider {

    String value() default "山东";

}

运行结果：