JAVADOC

package org.springframework.util;

/**
 * Miscellaneous {@link String} utility methods.
 *
 * 
Mainly for internal use within the framework; consider
 * Apache's Commons Lang
 * for a more comprehensive suite of {@code String} utilities.
 *
 * 
This class delivers some simple functionality that should really be
 * provided by the core Java {@link String} and {@link StringBuilder}
 * classes. It also provides easy-to-use methods to convert between
 * delimited strings, such as CSV strings, and collections and arrays.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rob Harrop
 * @author Rick Evans
 * @author Arjen Poutsma
 * @author Sam Brannen
 * @author Brian Clozel
 * @since 16 April 2001
 */
public abstract class StringUtils {

	/**
	 * Decode the given encoded URI component value. Based on the following rules:
	 * 

	 * 
Alphanumeric characters {@code "a"} through {@code "z"}, {@code "A"} through {@code "Z"},
	 * and {@code "0"} through {@code "9"} stay the same.
	 * 
Special characters {@code "-"}, {@code "_"}, {@code "."}, and {@code "*"} stay the same.
	 * 
A sequence "{@code %xy}" is interpreted as a hexadecimal representation of the character.
	 * 
	 * 
	 * @param source the encoded String
	 * @param charset the character set
	 * @return the decoded value
	 * @throws IllegalArgumentException when the given source contains invalid encoded sequences
	 * @since 5.0
	 * @see java.net.URLDecoder#decode(String, String)
	 */
	public static String uriDecode(String source, Charset charset) {}
}

package com.example.demo;

/**
 * 类 {@code OrderService} 订单服务层.
 *
 * 
 主要包括 创建订单、取消订单、查询订单等功能更
 *
 * @see Order
 * @author Mengday Zhang
 * @since 2018/5/12
 */
public class OrderService {

	/** 默认数量 {@value} */
    private static final Integer QUANTITY = 1;

    /**
     * 创建订单.
     *
     * 
 创建订单需要传用户id和商品列表(商品id和商品数量).
     *
     * 
{@code
     *  演示如何使用该方法
     *  List items = new ArrayList<>();
     *  Goods goods = new Goods(1L, BigDecimal.ONE);
     *  Goods goods2 = new Goods(2L, BigDecimal.TEN);
     *  items.add(goods);
     *  items.add(goods2);
     *
     *  Order order1 = new Order();
     *  order.setUserId("1");
     *  order.setItems(items);
     *  OrderService#createOrder(order);
     * }
     * 
     *
     * @param order 订单信息
     * @throws NullPointerException 参数信息为空
     * @exception IllegalArgumentException  数量不合法
     * @return 是否创建成功
     * @version 1.0
     * @see {@link Order}
     */
    public boolean createOrder(Order order) throws IllegalArgumentException{
        Objects.requireNonNull(order);

        List items = order.getItems();
        items.forEach(goods -> {
            BigDecimal quantity = goods.getQuantity();
            if (quantity == null || BigDecimal.ZERO.compareTo(quantity) == 0) {
                throw new IllegalArgumentException();
            }
        });

        System.out.println("create order...");

        return true;
    }
}