写一个Java的校园的商品管理系统

好的，校园商品管理系统可以包含以下功能：

1. 商品管理：包括商品的添加、修改、删除和查询功能；
2. 库存管理：包括库存的入库、出库、盘点和查询功能；
3. 销售管理：包括销售的录入、统计和查询功能；
4. 用户管理：包括用户的注册、登录、修改密码和退出登录功能；
5. 数据统计：包括商品销售量、库存量和销售额的统计功能。

以下是一个简单的Java代码实现：

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

public class CampusGoodsManagementSystem {
    
    private static HashMap<Integer, Goods> goodsMap = new HashMap<>();
    private static ArrayList<Inventory> inventoryList = new ArrayList<>();
    private static ArrayList<Sale> saleList = new ArrayList<>();
    private static ArrayList<User> userList = new ArrayList<>();
    private static User currentUser = null;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        boolean isExit = false;
        while (!isExit) {
            System.out.println("欢迎使用校园商品管理系统！");
            System.out.println("1.用户登录");
            System.out.println("2.用户注册");
            System.out.println("3.商品管理");
            System.out.println("4.库存管理");
            System.out.println("5.销售管理");
            System.out.println("6.数据统计");
            System.out.println("0.退出系统");
            System.out.print("请选择操作：");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    login();
                    break;
                case 2:
                    register();
                    break;
                case 3:
                    goodsManagement();
                    break;
                case 4:
                    inventoryManagement();
                    break;
                case 5:
                    saleManagement();
                    break;
                case 6:
                    dataStatistics();
                    break;
                case 0:
                    isExit = true;
                    break;
                default:
                    System.out.println("输入错误，请重新选择！");
                    break;
            }
        }
        System.out.println("谢谢使用校园商品管理系统！");
    }

    private static void login() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入用户名：");
        String username = scanner.nextLine();
        System.out.print("请输入密码：");
        String password = scanner.nextLine();
        for (User user : userList) {
            if (user.getUsername().equals(username) && user.getPassword().equals(password)) {
                currentUser = user;
                System.out.println("登录成功！");
                return;
            }
        }
        System.out.println("用户名或密码错误，登录失败！");
    }

    private static void register() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入用户名：");
        String username = scanner.nextLine();
        System.out.print("请输入密码：");
        String password = scanner.nextLine();
        User user = new User(username, password);
        userList.add(user);
        System.out.println("注册成功！");
    }

    private static void goodsManagement() {
        if (currentUser == null) {
            System.out.println("请先登录！");
            return;
        }
        Scanner scanner = new Scanner(System.in);
        System.out.println("1.添加商品");
        System.out.println("2.修改商品");
        System.out.println("3.删除商品");
        System.out.println("4.查询商品");
        System.out.print("请选择操作：");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.print("请输入商品编号：");
                int id = scanner.nextInt();
                System.out.print("请输入商品名称：");
                String name = scanner.nextLine();
                System.out.print("请输入商品价格：");
                double price = scanner.nextDouble();
                Goods goods = new Goods(id, name, price);
                goodsMap.put(id, goods);
                System.out.println("添加成功！");
                break;
            case 2:
                System.out.print("请输入要修改的商品编号：");
                int idToUpdate = scanner.nextInt();
                if (!goodsMap.containsKey(idToUpdate)) {
                    System.out.println("商品不存在！");
                    return;
                }
                Goods goodsToUpdate = goodsMap.get(idToUpdate);
                System.out.print("请输入新的商品名称（留空表示不修改）：");
                String newName = scanner.nextLine();
                if (!newName.isEmpty()) {
                    goodsToUpdate.setName(newName);
                }
                System.out.print("请输入新的商品价格（留空表示不修改）：");
                String newPriceStr = scanner.nextLine();
                if (!newPriceStr.isEmpty()) {
                    double newPrice = Double.parseDouble(newPriceStr);
                    goodsToUpdate.setPrice(newPrice);
                }
                System.out.println("修改成功！");
                break;
            case 3:
                System.out.print("请输入要删除的商品编号：");
                int idToDelete = scanner.nextInt();
                if (!goodsMap.containsKey(idToDelete)) {
                    System.out.println("商品不存在！");
                    return;
                }
                goodsMap.remove(idToDelete);
                System.out.println("删除成功！");
                break;
            case 4:
                System.out.print("请输入要查询的商品编号：");
                int idToQuery = scanner.nextInt();
                if (!goodsMap.containsKey(idToQuery)) {
                    System.out.println("商品不存在！");
                    return;
                }
                Goods goodsToQuery = goodsMap.get(idToQuery);
                System.out.println("商品编号：" + goodsToQuery.getId());
                System.out.println("商品名称：" + goodsToQuery.getName());
                System.out.println("商品价格：" + goodsToQuery.getPrice());
                break;
            default:
                System.out.println("输入错误，请重新选择！");
                break;
        }
    }

    private static void inventoryManagement() {
        if (currentUser == null) {
            System.out.println("请先登录！");
            return;
        }
        Scanner scanner = new Scanner(System.in);
        System.out.println("1.入库");
        System.out.println("2.出库");
        System.out.println("3.盘点");
        System.out.println("4.查询库存");
        System.out.print("请选择操作：");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.print("请输入商品编号：");
                int id = scanner.nextInt();
                if (!goodsMap.containsKey(id)) {
                    System.out.println("商品不存在！");
                    return;
                }
                System.out.print("请输入入库数量：");
                int quantityIn = scanner.nextInt();
                Inventory inventoryIn = new Inventory(id, quantityIn);
                inventoryList.add(inventoryIn);
                System.out.println("入库成功！");
                break;
            case 2:
                System.out.print("请输入商品编号：");
                int idOut = scanner.nextInt();
                if (!goodsMap.containsKey(idOut)) {
                    System.out.println("商品不存在！");
                    return;
                }
                System.out.print("请输入出库数量：");
                int quantityOut = scanner.nextInt();
                if (!isInventoryEnough(idOut, quantityOut)) {
                    System.out.println("库存不足！");
                    return;
                }
                Inventory inventoryOut = new Inventory(idOut, -quantityOut);
                inventoryList.add(inventoryOut);
                System.out.println("出库成功！");
                break;
            case 3:
                System.out.print("请输入商品编号：");
                int idCheck = scanner.nextInt();
                if (!goodsMap.containsKey(idCheck)) {
                    System.out.println("商品不存在！");
                    return;
                }
                int quantityCheck = getInventoryQuantity(idCheck);
                System.out.println("商品编号：" + idCheck);
                System.out.println("库存数量：" + quantityCheck);
                break;
            case 4:
                System.out.println("商品编号\t库存数量");
                for (Inventory inventory : inventoryList) {
                    int idQuery = inventory.getGoodsId();
                    int quantityQuery = getInventoryQuantity(idQuery);
                    System.out.println(idQuery + "\t" + quantityQuery);
                }
                break;
            default:
                System.out.println("输入错误，请重新选择！");
                break;
        }
    }

    private static boolean isInventoryEnough(int goodsId, int quantity) {
        int currentQuantity = getInventoryQuantity(goodsId);
        return currentQuantity >= quantity;
    }

    private static int getInventoryQuantity(int goodsId) {
        int quantity = 0;
        for (Inventory inventory : inventoryList) {
            if (inventory.getGoodsId() == goodsId) {
                quantity += inventory.getQuantity();
            }
        }
        return quantity;
    }

    private static void saleManagement() {
        if (currentUser == null) {
            System.out.println("请先登录！");
            return;
        }
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入商品编号：");
        int id = scanner.nextInt();
        if (!goodsMap.containsKey(id)) {
            System.out.println("商品不存在！");
            return;
        }
        System.out.print("请输入销售数量：");
        int quantity = scanner.nextInt();
        if (!isInventoryEnough(id, quantity)) {
            System.out.println("库存不足！");
            return;
        }
        double price = goodsMap.get(id).getPrice();
        double totalPrice = price * quantity;
        Sale sale = new Sale(id, quantity, totalPrice);
        saleList.add(sale);
        Inventory inventory = new Inventory(id, -quantity);
        inventoryList.add(inventory);
        System.out.println("销售成功！");
    }

    private static void dataStatistics() {
        if (currentUser == null) {
            System.out.println("请先登录！");
            return;
        }
        double totalSales = 0;
        for (Sale sale : saleList) {
            totalSales += sale.getTotalPrice();
        }
        System.out.println("商品销售总额：" + totalSales);
        System.out.println("商品销售统计：");
        System.out.println("商品编号\t销售数量\t销售额");
        for (Sale sale : saleList) {
            int id = sale.getGoodsId();
            int quantity = sale.getQuantity();
            double totalPrice = sale.getTotalPrice();
            System.out.println(id + "\t" + quantity + "\t" + totalPrice);
        }
    }

    private static class Goods {
        private int id;
        private String name;
        private double price;

        public Goods(int id, String name, double price) {
            this.id = id;
            this.name = name;
            this.price = price;
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.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;
        }
    }

    private static class Inventory {
        private int goodsId;
        private int quantity;

        public Inventory(int goodsId, int quantity) {
            this.goodsId = goodsId;
            this.quantity = quantity;
        }

        public int getGoodsId() {
            return goodsId;
        }

        public void setGoodsId(int goodsId) {
            this.goodsId = goodsId;
        }

        public int getQuantity() {
            return quantity;
        }

        public void setQuantity(int quantity) {
            this.quantity = quantity;
        }
    }

    private static class Sale {
        private int goodsId;
        private int quantity;
        private double totalPrice;

        public Sale(int goodsId, int quantity, double totalPrice) {
            this.goodsId = goodsId;
            this.quantity = quantity;
            this.totalPrice = totalPrice;
        }

        public int getGoodsId() {
            return goodsId;
        }

        public void setGoodsId(int goodsId) {
            this.goodsId = goodsId;
        }

        public int getQuantity() {
            return quantity;
        }

        public void setQuantity(int quantity) {
            this.quantity = quantity;
        }

        public double getTotalPrice() {
            return totalPrice;
        }

        public void setTotalPrice(double totalPrice) {
            this.totalPrice = totalPrice;
        }
    }

    private static class User {
        private String username;
        private String password;

        public User(String username, String password) {
            this.username = username;
            this.password = password;
        }

        public String getUsername() {
            return username;
        }

        public void setUsername(String username) {
            this.username = username;
        }

        public String getPassword() {
            return password;
        }

        public void setPassword(String password) {
            this.password = password;
        }
    }
}

当然，这只是一个简单的实现，实际开发中需要考虑更多的细节和功能。