简单使用自定义注解

import java.lang.annotation.*;

@Target(ElementType.FIELD)  //@Target修饰注解作用的范围，FIELD说明作用于描述域，其他选项可以百度获取
@Retention(RetentionPolicy.RUNTIME) //@Retention说明注解被保留的级别，RUNTIME说明运行时有效，其他选项可以百度获取
@Documented //@Documented表明该注解可以被javadoc类的工具文档化
public @interface FruitProvider {
    //供应商编号
    public int id() default -1;
    //供应商名称
    public String name() default "";
    //供应商地址
    public String address() default "";
}

import java.lang.reflect.Field;

public class FruitInfoUtil {
    public static void getFruitInfo(Class<?> clazz) {
        String strFruitProvider = "供应商信息：";

        Field[] fields = clazz.getDeclaredFields();//通过反射获取处理注解
        for (Field field : fields) {
            //如果成员被该注解标注
            if (field.isAnnotationPresent(FruitProvider.class)) {
                //拿到对应的注解信息
                FruitProvider fruitProvider = (FruitProvider) field.getAnnotation(FruitProvider.class);
                //处理注解信息
                strFruitProvider = "供应商编号：" + fruitProvider.id() + " 供应商名称："+ fruitProvider.name()
                        + " 供应商地址：" + fruitProvider.address();
                System.out.println(strFruitProvider);
            }
        }
    }
}

public class Apple {
    
    @FruitProvider(id = 1,name = "陕西红富士",address = "陕西省西安市")
    private String appleProvider;

    public void setAppleProvider(String appleProvider) {
        this.appleProvider = appleProvider;
    }

    public String getAppleProvider() {
        return appleProvider;
    }
}

public class Test {
    public static void main(String[] args) {
        FruitInfoUtil.getFruitInfo(Apple.class);
    }
}

供应商编号：1 供应商名称：陕西红富士 供应商地址：陕西省西安市