java设计模式【之】外观模式【源码】【场景：积分兑换图书】

package com.sjms._06_外观模式; /** * 兑换系统 */ public class ExchangeSystem { BookSystem bookSystem = new BookSystem(); JiFenSystem jiFenSystem = new JiFenSystem(); WuLiuSystem wuLiuSystem = new WuLiuSystem(); /** * 兑换图书 */ String convertBook(String bookName) { //积分系统扣积分 String status = jiFenSystem.deductBook(bookName); if (status == null) { System.out.println("兑换《" + bookName + "》失败，积分不足"); return null; } //图书系统兑换图书 String book = bookSystem.getBook(bookName); if (book == null) { System.out.println("兑换失败，图书库存不足"); return null; } //物流系统发货 String transportStatus = wuLiuSystem.transportBook(book); if (transportStatus == null) { System.out.println("兑换失败，物流系统异常"); return null; } return "ok"; } }