java新手的第一个小东西，或许小东西都算不上=。 =

import java.util.ArrayList;import java.util.Scanner;

/*** 系统类** @author Administrator**/public class Systems {private Scanner input = new Scanner(System.in);private Database db = new Database();//用户数据库private ArrayList<Users> usersList = db.getUsersList();//商品数据库private ArrayList<Goods> goodsList = db.getGoodsList();//登录用户Users user = null;//购物车信息private ArrayList<Goods> shoppingCart = new Database().getShoppingCart();/*** 显示主菜单*/public int getMainMenu() {System.out.println("****************** 欢迎使用大神超市管理系统 ******************");System.out.println("****************** 【1】 用 户 登 录 ******************");System.out.println("****************** 【2】 用 户 注 册 ******************");System.out.println("****************** 【3】 退 出 系 统 ******************");System.out.print("请输入编号选择功能: ");return input.nextInt();}/***显示二级菜单*/public int getSecondMenu(){System.out.println("****************** 【1】 查看购买商品 ******************");System.out.println("****************** 【2】 查看购物车信息 ******************");System.out.println("****************** 【3】 在线冲值 ******************");System.out.println("****************** 【4】 添加商品 ******************");System.out.println("****************** 【5】 返回上一级菜单 ******************");System.out.print("请输入编号选择功能: ");return input.nextInt();}/*** 用户登录*/public boolean login(){System.out.print("请输入帐号: ");String name = input.next();System.out.print("请输入密码: ");String password = input.next();//标记 false 表示不存在boolean flag = false;//遍历用户数据库 , 查找该用户是否存在for(Users u : usersList){if( u.getName().equals(name) && u.getPassword().equals(password) ){this.user = u;//修改标记flag = true;}}return flag;}/*** 用户注册*/public void register(){//输入新账号System.out.print("请输入新帐号: ");String name = input.next();//标记boolean flag = true;for(Users i : usersList){if(i.getName().equals(name)){//修改标记flag = false;}}//判断if(flag){System.out.print("请输入密码: ");String password = input.next();usersList.add(new Users(name,password));System.out.println("注册成功！"+name+"欢迎您！");//this.user.setName(name);//this.user.setPassword(password);usersList.add(new Users(name,password));this.mainLogic();}else{System.out.println("注册失败 ！");this.register();}}/*** 显示所有商品信息*/public void showAllGoods(){System.out.println("商品ID****商品名****单价****库存******\n");for(Goods g : goodsList){System.out.println( g.getID()+"\t"+g.getName()+"\t"+g.getPrice()+"\t"+g.getStock());}}/*** 购买*/public void buy(){this.showAllGoods();System.out.print("请输入需要购买的商品ID(输入 0 返回上级菜单)：");int goodsID = input.nextInt();if(goodsID == 0){this.secondLogic();}boolean flag = false;//克隆Goods good = null;//现在购买的商品的信息Goods gs = null;for(Goods g : goodsList){if( g.getID() == goodsID ){flag = true;gs = g;good = new Goods(g.getID(),g.getName(),g.getPrice(),0);}}if(flag){System.out.print("请输入要购买的商品数量：");int count = input.nextInt();if(count > gs.getStock()){System.out.println("库存不足，请重新购买！\n");this.buy();}else{double total = gs.getPrice()*count;if(total > user.getBalance()){System.out.println("余额不足，请重新购买！\n");this.buy();}else{System.out.println("购买成功，账户余额"+(user.getBalance()-total)+"元！"+"本次花费"+total+"元！");//扣费user.setBalance(user.getBalance()-total);//更新商品列表gs.setStock(gs.getStock()-count);/*** 将购买信息加入购物车* 判断该次购买商品是否为第一次加入购物车，是则直接调用setStock(count)方法* 否则 setStock(count+getStock())*/boolean flag2 = true;for(Goods g : shoppingCart){if(g.getID() == goodsID){flag2 = false;g.setStock(g.getStock()+count);}}if(flag2){good.setStock(count);shoppingCart.add(good);}this.buy();}}}else{System.err.println("您输入的商品ID不存在，请重新输入！\n");this.buy();}}/*** 查看购物车信息*/public void showShoppingCart(){System.out.println("用户名***********余额*******");System.out.println(user.getName()+"\t\t"+user.getBalance());System.out.println("商品ID****商品名****单价****库存******\n");for(Goods g : shoppingCart){System.out.println(g.getID()+"\t"+g.getName()+"\t"+g.getPrice()+"\t"+g.getStock());}System.out.print("输入任意键返回上级：");String temp = input.next();this.secondLogic();}/*** 在线充值*/public void recharge(){System.out.print("请输入充值金额：");double m = input.nextDouble();user.setBalance(m + user.getBalance());System.out.print("充值成功，是否继续充值：(yes/no)");String ys = input.next();if(ys.equalsIgnoreCase("yes".trim())){this.recharge();}else{this.secondLogic();}}/*** 添加商品*/public void addGoods(){/*** 选择添加商品类型：1.已存在商品（只添加数量）* 2.不存在商品（添加ID，商品名，价格，数量）*/System.out.println("请选择要添加的商品类型：【1】已存在的商品。【2】不存在的商品");int choose = input.nextInt();switch(choose){case 1://已存在的商品this.existGoods();break;case 2://不存在数据库中的商品this.unexistGoods();break;default:System.err.println("输入错误！请重新输入");this.addGoods();}}/*** 已存在的商品*/public void existGoods(){System.out.println("请输入商品名：");String goodName = input.next();//判断商品名是否存在boolean flag = true;for(Goods g : goodsList){if(goodName.equalsIgnoreCase(g.getName().trim())){flag = false;System.out.println("请输入添加商品数量：");int count = input.nextInt();g.setStock(g.getStock()+count);}}if(flag){System.out.print("商品不存在，请重新输入！");this.existGoods();}System.out.print("商品添加成功，是否继续添加（yes/no）：");String temp = input.next();if(temp.equalsIgnoreCase("yes".trim())){this.addGoods();}else{this.secondLogic();}this.showAllGoods();}/*** 不存在的商品*/public void unexistGoods(){//新商品名System.out.print("请输入商品名：");String goodName = input.next();//新商品价格System.out.print("请输入商品价格：");double goodPrice = input.nextDouble();//新商品数量System.out.print("请输入商品数量：");int goodStock = input.nextInt();int goodsID = goodsList.size()+1;goodsList.add(new Goods(goodsID,goodName,goodPrice,goodStock));System.out.println("添加成功，是否继续添加：(yes/no)");String ys = input.next();if(ys.equalsIgnoreCase("yes".trim())){this.addGoods();}else{this.secondLogic();}}/*** 核心逻辑控制方法*/public void mainLogic() {// 启动主菜单int id = this.getMainMenu();// 判断switch (id) {case 1://用户登录if( this.login() ){System.err.println("欢迎" + this.user.getName() + "登录成功 !");//this.getSecondMenu();this.secondLogic();}else{System.err.println("登录失败 !");}break;case 2://用户注册this.register();break;case 3:System.err.println("退出系统 , 谢谢使用 !");//退出系统System.exit(0);break;default:System.err.println("您输入的编号无效 , 请重新输入　!\n");//开始递归this.mainLogic();break;}}/*** 二级菜单操作控制*/public void secondLogic () {int id = this.getSecondMenu();switch(id){case 1:this.buy();break;case 2:this.showShoppingCart();break;case 3:this.recharge();break;case 4:this.addGoods();break;case 5:this.mainLogic();break;default:System.out.println("输入错误！");this.secondLogic();}}}/*** 用户对象* @author Administrator*/public class Users {//帐号private String name;//密码private String password;//用户账户余额private double balance = 100;//构造器public Users() {}public Users(String name, String password) {this.name = name;this.password = password;}public Users(String name, String password, double balance) {this.name = name;this.password = password;this.balance = balance;}//getter , setterpublic String getName() {return name;}public void setName(String name) {this.name = name;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public double getBalance() {return balance;}public void setBalance(double balance) {this.balance = balance;}}public class Goods {//商品编号private int ID;//商品名private String name;//价格private double price;//存量private int stock;//构造器定义public Goods() {}public Goods(int iD, String name, double price, int stock) {ID = iD;this.name = name;this.price = price;this.stock = stock;}//getter , settet;public int getID() {return ID;}public void setID(int iD) {ID = iD;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public int getStock() {return stock;}public void setStock(int stock) {this.stock = stock;}}import java.util.ArrayList;/*** 数据库类* @author Administrator*/public class Database {//模拟用户数据库private ArrayList<Users> usersList = new ArrayList<Users>();//模拟商品数据库private ArrayList<Goods> goodsList = new ArrayList<Goods>();//购物车private ArrayList<Goods> shoppingCart = new ArrayList<Goods>();/*** 构造器* @return*/public Database(){//添加一条默认用户数据Users users = new Users("admin","admin");usersList.add(users);//添加一条默认商品数据goodsList.add(new Goods(1,"苹果",5.0,1000));goodsList.add(new Goods(2,"牙刷",3,100));goodsList.add(new Goods(3,"梨子",4,1000));goodsList.add(new Goods(4,"节操",99999,0));goodsList.add(new Goods(5,"甲胺磷",24,20));goodsList.add(new Goods(6,"肥皂",5,300));goodsList.add(new Goods(7,"衬衫",100,20));goodsList.add(new Goods(8,"酸奶",2.5,2000));goodsList.add(new Goods(9,"iphone",5000,3));}public ArrayList<Users> getUsersList() {return usersList;}public void setUsersList(ArrayList<Users> usersList) {this.usersList = usersList;}public ArrayList<Goods> getGoodsList() {return goodsList;}public void setGoodsList(ArrayList<Goods> goodsList) {this.goodsList = goodsList;}public ArrayList<Goods> getShoppingCart() {return shoppingCart;}public void setShoppingCart(ArrayList<Goods> shoppingCart) {this.shoppingCart = shoppingCart;}}public class SystemTest {public static void main(String[] args) {//启动系统Systems system = new Systems();system.mainLogic();}}本文出自 “新手出门” 博客，谢绝转载！