package com.itranswarp.learnjava;

import java.lang.reflect.Field;

/**
 * Learn Java from https://www.liaoxuefeng.com/
 * 
 * @author liaoxuefeng
 */
public class Main {

	public static void main(String[] args) throws Exception {
		Person p1 = new Person("Bob", "Beijing", 20);
		Person p2 = new Person("", "Shanghai", 20);
		Person p3 = new Person("Alice", "Shanghai", 199);
		for (Person p : new Person[] { p1, p2, p3 }) {
			try {
				check(p);
				System.out.println("Person " + p + " checked ok.");
			} catch (IllegalArgumentException e) {
				System.out.println("Person " + p + " checked failed: " + e);
			}
		}
	}

	static void check(Person person) throws IllegalArgumentException, ReflectiveOperationException {
		//通过 foreach循环，依次获取person这个实例的public的字段的字段名称（数据类型为Field）
		for (Field field : person.getClass().getFields()) {
			
			//通过Filed类的 .getAnnotation 方法来获得注解
			Range range = field.getAnnotation(Range.class);
			
			//判断注解是否为null
			if (range != null) {
				
				//使用了注解的情况下，通过Filed的 .get方法，来获取指定字段的字段值
				Object value = field.get(person);
				// TODO:
				
				//如果是对 String字段使用的注解
				if (value instanceof String) {
					String s = (String) value;
					if (s.length()<range.min() || s.length()>range.max()) {
						throw new IllegalArgumentException("Invalid filed: "+field.getName());
					}
				}
				
				//如果是对 int字段使用的注解
				if (value instanceof Integer) {
					int i = (int) value;
					if (i<range.min() || i>range.max()) {
						throw new IllegalArgumentException("Invalid filed: "+field.getName());
					}
				}
				
			}
		}
	}
}