实现功能：商品查询，新增，更改价格，以及删除

首先是三个基本类的构建

商品类、账号类、品牌类

1、商品类

public class Goods { //商品信息：商品名称，商品价格，商品销量，商品种类，商品品牌对应编号 private String goodsName; private double goodsPrice; private int goodsSales; private String goodsCategories; private int brandsNum; private String GoodsNum; public Goods(String goodsName, double goodsPrice, int goodsSales, String goodsCategories,int brandsNum, String goodsNum) { this.goodsName = goodsName; this.goodsPrice = goodsPrice; this.goodsSales = goodsSales; this.goodsCategories = goodsCategories; this.brandsNum = brandsNum; GoodsNum = goodsNum; } public int getBrandsNum() { return brandsNum; } public void setBrandsNum(int brandsNum) { this.brandsNum = brandsNum; } public Goods() { } public String getGoodsNum() { return GoodsNum; } public void setGoodsNum(String goodsNum) { GoodsNum = goodsNum; } public String getGoodsName() { return goodsName; } public void setGoodsName(String goodsName) { this.goodsName = goodsName; } public double getGoodsPrice() { return goodsPrice; } public void setGoodsPrice(double goodsPrice) { this.goodsPrice = goodsPrice; } public int getGoodsSales() { return goodsSales; } public void setGoodsSales(int goodsSales) { this.goodsSales = goodsSales; } public String getGoodsCategories() { return goodsCategories; } public void setGoodsCategories(String goodsCategories) { this.goodsCategories = goodsCategories; } public int getBrands() { return brandsNum; } public void setBrands(int brandsNum) { this.brandsNum = brandsNum; }}

实现了其各个属性的get和set方法

账户类

public class Accounts { //账户信息：账户名称，账户密码 private String userName; private String userPassword; public Accounts(String userName, String userPassword) { this.userName = userName; this.userPassword = userPassword; } public Accounts() { } public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPassword() { return userPassword; } public void setUserPassword(String userPassword) { this.userPassword = userPassword; }}

品牌类

public class Brands { //商品品牌信息：商品品牌名称，商品品牌对应编号 private String brandsName; private int brandsNum; public Brands(String brandsName, int brandsNum) { this.brandsName = brandsName; this.brandsNum = brandsNum; } public String getBrandsName() { return brandsName; } public void setBrandsName(String brandsName) { this.brandsName = brandsName; } public int getBrandsNum() { return brandsNum; } public void setBrandsNum(int brandsNum) { this.brandsNum = brandsNum; }}

之后是一个存储这三个基本类信息的数据类，通过定义List实现三个类的存储

数据类

import java.util.ArrayList;import java.util.List;import java.util.UUID;public class Database { //存储用户信息 private List<Accounts>accountsList=new ArrayList<>(); //存储商品信息 private List<Goods>goodsList=new ArrayList<>(); //存储品牌信息 private List<Brands>brandsList=new ArrayList<>(); public Database(){ //添加初始化信息 此处自己添加商品，用户信息，品牌信息 } public List<Accounts> getAccountsList() { return accountsList; } public void setAccountsList(List<Accounts> accountsList) { this.accountsList = accountsList; } public List<Goods> getGoodsList() { return goodsList; } public void setGoodsList(List<Goods> goodsList) { this.goodsList = goodsList; } public List<Brands> getBrandsList() { return brandsList; } public void setBrandsList(List<Brands> brandsList) { this.brandsList = brandsList; }}

之后是三个基本类各个增删改查方法的实现，这个根据程序需求写

商品交互类

import java.util.ArrayList;import java.util.List;public class GoodsDAO { //调用数据库 private Database database; //初始化商品DAO类，引入数据库 public GoodsDAO(Database database){ this.database=database; } //返回销量最高的商品 public List<Goods>hotSell(){ List<Goods> temporList=database.getGoodsList(); for(int i=0;i<temporList.size();i++){ for(int j=0;j<temporList.size()-1-i;j++){ if(temporList.get(j).getGoodsSales()<temporList.get(j+1).getGoodsSales()) { Goods e=temporList.get(j+1); temporList.set(j+1,temporList.get(j)); temporList.set(j,e); } } } return temporList; } //根据商品序号查询商品 public Goods searchById(int id){ Goods goods; goods=database.getGoodsList().get(id-1); return goods; } //根据品牌编号查询商品 public List<Goods>searchByBranchId(int brandsId){ List<Goods>temporList=new ArrayList<>(); for(Goods each:database.getGoodsList()){ if(each.getBrandsNum()==brandsId) temporList.add(each); } if(temporList.isEmpty()) temporList=null; return temporList; } //根据价格区间查询商品 public List<Goods>searchByPrice(double minPrice,double maxPrice){ List<Goods>temporList=new ArrayList<>(); for(Goods each:database.getGoodsList()){ if(each.getGoodsPrice()>=minPrice&&each.getGoodsPrice()<=maxPrice) { temporList.add(each); } } if(temporList.isEmpty()) temporList=null; return temporList; } //新增商品 public void addGoods(Goods goods){ database.getGoodsList().add(goods); } //修改商品价格 public void modify(String goodsId,double price){ for(Goods each:database.getGoodsList()){ if(each.getGoodsNum().equals(goodsId)) each.setGoodsPrice(price); } } //删除商品 public void delete(String goodsId){ Goods goods=null; for(Goods each:database.getGoodsList()){ if(each.getGoodsNum().equals(goodsId)) goods=each; } database.getGoodsList().remove(goods); //迭代操作时不允许ArrayList被改变，因此重新定义一个对象指向他，迭代完后进行操作。 } //更改商品品牌编号 public void changeByBranchId(int brandsId){ for(Goods each:database.getGoodsList()){ if(each.getBrandsNum()==brandsId) each.setBrandsNum(brandsId-1); } }}

账户交互类实现注册，登录的需求

public class AccountDAO { //调用数据库 private Database database; //初始化账户DAO类，引入数据库 public AccountDAO(Database database){ this.database=database; } //根据账户名返回账户类 public Accounts searchAccounts(String userName){ Accounts accounts=null; for(Accounts each:database.getAccountsList()){ if(each.getUserName().equals(userName)) accounts=each; } return accounts; } //添加账户类 public void addAccount(Accounts accounts){ database.getAccountsList().add(accounts); }}

品牌类

public class BrandsDAO { //调用数据库 private Database database; //初始化品牌DAO类，引入数据库 public BrandsDAO(Database database){ this.database=database; } //根据品牌名称查询 public Brands findByName(String brandName){ Brands brands=null; for(Brands each:database.getBrandsList()){ if(each.getBrandsName().equals(brandName)) { brands = each; break; } } return brands; } //查询所有品牌 public void findAll(){ System.out.println("现有品牌："); for(Brands each:database.getBrandsList()){ System.out.println(each.getBrandsNum()+"\t"+each.getBrandsName()); } } //根据品牌编号查询品牌名称 public String findNameById(int id){ String brandName; Brands brands=null; for(Brands each:database.getBrandsList()){ if(each.getBrandsNum()==id){ brands=each; } } return brands.getBrandsName(); } //查询品牌是否拥有 public boolean findBranch(String brandsName){ boolean choose=false; for(Brands each:database.getBrandsList()) { if(each.getBrandsName().equals(brandsName)) choose=true; } return choose; } //新建一个品牌 public void addBranch(Brands brands){ database.getBrandsList().add(brands); } //查找当前品牌的的数量 public int brandsNumbers(){ int num=database.getBrandsList().size(); return num; } //查找要删除的品牌 public void deleteBrands(int num){ Brands brands=null; for(Brands each:database.getBrandsList()){ if(each.getBrandsNum()==num) brands=each; } database.getBrandsList().remove(brands); } //移动编号 public void moveBrandsNum(int brandsNum){ int index; for(int i=0;i<database.getBrandsList().size();i++){ if(database.getBrandsList().get(i).getBrandsNum()>brandsNum) database.getBrandsList().get(i).setBrandsNum(database.getBrandsList().get(i).getBrandsNum()-1); } }}

服务类实现项目需要的功能，构建交互界面

public class GoodsSystem { Scanner scanner=new Scanner(System.in); Random random=new Random(); AccountDAO accountDAO; BrandsDAO brandsDAO; GoodsDAO goodsDAO; //初始化DAO public GoodsSystem(Database database){ accountDAO=new AccountDAO(database); brandsDAO=new BrandsDAO(database); goodsDAO=new GoodsDAO(database); } public void start(){// 1.登陆 System.out.println("----------------商品系统---------------"); System.out.println("1.登录");// 2.注册 System.out.println("2.注册");// 3.退出系统 System.out.println("3.退出系统"); System.out.println("请选择："); String choose=scanner.next(); switch(choose){ //登录 case "1": login(); break; //注册 case "2": regist(); break; //退出系统 case "3": System.out.println("系统已经退出"); break; default: System.out.println("输入错误，请重新输入："); start(); } } //登录 public void login(){ System.out.println("请输入用户名："); String userName=scanner.next(); System.out.println("请输入密码："); String passWord=scanner.next(); Accounts accounts=accountDAO.searchAccounts(userName); String testNum=""; if(accounts!=null){ if(accounts.getUserPassword().equals(passWord)){ for(int i=0;i<4;i++){ int num=random.nextInt(10); testNum=testNum+num; } System.out.println("验证码："+testNum); System.out.println("请输入验证码："); String testNumInput=scanner.next(); if(testNumInput.equals(testNum)) { System.out.println("登录成功"); mainMenu(); } else{ System.out.println("验证码错误，请重新登录"); login(); } } else{ System.out.println("密码错误，请重新登录"); System.out.println("输入任意键执行操作，或输入0返回上一层目录"); String choose=scanner.next(); if(choose.equals("0")) start(); else login(); } } else{ System.out.println("该账户不存在，请重新输入："); System.out.println("输入任意键执行操作，或输入0返回上一层目录"); String choose=scanner.next(); if(choose.equals("0")) start(); else login(); } } //注册 public void regist(){ System.out.println("----注册----"); //用户名 System.out.println("请输入用户名："); String userName=scanner.next(); Accounts accounts=accountDAO.searchAccounts(userName); while(accounts!=null){ System.out.println("用户名已经被使用，请重新输入"); userName=scanner.next(); accounts=accountDAO.searchAccounts(userName); } //密码 System.out.println("请输入密码："); String userPassWord=scanner.next(); System.out.println("确认密码："); String testPassWord=scanner.next(); while(!userPassWord.equals(testPassWord)){ System.out.println("确认密码与注册密码不相符，请重新输入密码"); System.out.println("请输入密码："); userPassWord=scanner.next(); System.out.println("确认密码："); testPassWord=scanner.next(); } //验证码 String testNum=""; for(int i=0;i<4;i++){ int num=random.nextInt(10); testNum=testNum+num; } System.out.println("验证码："+testNum); System.out.println("请输入验证码："); String testNumInput=scanner.next(); if(testNumInput.equals(testNum)) { accountDAO.addAccount(new Accounts(userName,userPassWord)); System.out.println("注册成功"); start(); } else{ System.out.println("验证码错误，请重新注册"); System.out.println("输入任意键执行操作，或输入0返回上一层目录"); String choose=scanner.next(); if(choose.equals("0")) start(); else regist(); } } //主菜单 public void mainMenu(){ System.out.println("-------------主菜单------------");// 1.热门商品 System.out.println("1.热门商品");// 2.商品查询 System.out.println("2.商品查询");// 3.后台管理 System.out.println("3.后台管理"); System.out.println("4.退出系统"); System.out.println("请输入你的选择："); String choose=scanner.next(); switch (choose){ case "1"://热门商品 hotSell(); break; case "2"://商品查询 searchGoods(); break; case "3"://后台管理 controlGoods(); break; case "4"://退出系统 System.out.println("系统已经退出"); break; default: mainMenu(); } } //热卖商品 public void hotSell(){ System.out.println("------------热销商品------------"); List <Goods>tempor=goodsDAO.hotSell(); System.out.println("序号\t\t"+"商品"+"\t\t\t\t\t销量\t"); int num=10; if(tempor.size()<10) num=tempor.size(); for(int i=0;i<num;i++){ System.out.println((i+1)+"\t\t"+tempor.get(i).getGoodsName()+"\t\t\t\t\t"+tempor.get(i).getGoodsSales()+"\t"); } System.out.println("请输入要查询的商品ID或输入0返回上一层菜单。"); String chooseEnd=scanner.next(); if(isNumeric(chooseEnd)==true) { int choose=Integer.parseInt(chooseEnd); if(choose==0){ mainMenu(); } else { if(choose<=num&&choose>=0) { Goods goods = goodsDAO.searchById(choose); System.out.println("商品名称\t\t品牌\t\t价格\t\t类型"); System.out.println(goods.getGoodsName() + "\t\t\t" + brandsDAO.findNameById(goods.getBrandsNum()) + "\t" + goods.getGoodsPrice() + "元\t" + goods.getGoodsCategories()); mainMenu(); } else { System.out.println("查询的序号超过限定，请重新输入"); hotSell(); } } } else { System.out.println("输入错误符号，请重新选择"); hotSell(); } } //商品查询 public void searchGoods(){ System.out.println("---------商品查询----------");// 1.品牌查询 System.out.println("1.品牌查询");// 2.价格查询 System.out.println("2.价格查询"); System.out.println("3.返回上一层目录"); System.out.println("请输入你的选择："); String choose=scanner.next(); switch(choose){ case "1"://品牌查询 searchByBranch(); break; case "2"://价格查询 searchByPrice(); break; case "3": mainMenu(); break; default: searchGoods(); } } //后台管理 public void controlGoods(){ System.out.println("--------后台管理--------");// 1.新增商品 System.out.println("1.新增商品");// 2.修改价格 System.out.println("2.修改价格");// 3.删除商品 System.out.println("3.删除商品"); System.out.println("4.返回主菜单"); System.out.println("请输入选择："); String choose=scanner.next(); switch (choose){ case "1"://新增商品 addGoods(); break; case "2"://修改价格 changePrice(); break; case "3"://删除商品 deleteGoods(); break; case "4"://返回主菜单 mainMenu(); break; default: controlGoods(); } } //根据品牌查询 public void searchByBranch(){ brandsDAO.findAll(); System.out.println("请输入要查询的品牌编号："); String brandsNum1=scanner.next(); if(isNumeric(brandsNum1)) { int brandsNum=Integer.parseInt(brandsNum1); List<Goods> temporlist = goodsDAO.searchByBranchId(brandsNum); if (temporlist == null) { System.out.println("没有该品牌的商品"); searchGoods(); } for (int i = 0; i < temporlist.size(); i++) { System.out.println("序号" + (i + 1) + "\t" + "商品名字：" + temporlist.get(i).getGoodsName()); } System.out.println("请输入要查询的商品ID或输入0返回上一层菜单。"); String choose1 = scanner.next(); if(isNumeric(choose1)) { int choose=Integer.parseInt(choose1); if (choose == 0) { searchGoods(); } else { if(choose>=1&&choose<=temporlist.size()){ Goods goods = temporlist.get(choose - 1); System.out.println("商品名称:" + goods.getGoodsName() + "\t" + "品牌:" + brandsDAO.findNameById(goods.getBrandsNum()) + "\t" + "价格:" + goods.getGoodsPrice() + "元\t" + "类型：" + goods.getGoodsCategories()); searchGoods(); } else{ System.out.println("输入序号超过边界范围，请重新输入"); searchByBranch(); } } } else{ System.out.println("输入错误符号，请重新选择"); searchByBranch(); } } else{ System.out.println("输入错误符号，请重新选择"); searchByBranch(); } } //根据价格查询 public void searchByPrice(){ System.out.println("请输入要查询的价格区间:最小价格 最大价格"); double minPrice=scanner.nextDouble(); double maxPrice=scanner.nextDouble(); List<Goods>temporlist=goodsDAO.searchByPrice(minPrice,maxPrice); if(temporlist==null){ System.out.println("没有该区间的商品"); searchGoods(); } for(int i=0;i<temporlist.size();i++){ System.out.println("序号"+(i+1)+"\t"+"商品名字："+temporlist.get(i).getGoodsName()); } System.out.println("请输入要查询的商品ID或输入0返回上一层菜单。"); String choose1 = scanner.next(); if(isNumeric(choose1)) { int choose=Integer.parseInt(choose1); if (choose == 0) { searchGoods(); } else { if(choose>=1&&choose<=temporlist.size()) { Goods goods = temporlist.get(choose - 1); System.out.println("商品名称:" + goods.getGoodsName() + "\t" + "品牌:" + brandsDAO.findNameById(goods.getBrandsNum()) + "\t" + "价格:" + goods.getGoodsPrice() + "元\t" + "类型：" + goods.getGoodsCategories()); searchGoods(); } else{ System.out.println("输入数字超过边界，请重新输入"); searchByPrice(); } } } else{ System.out.println("输入错误符号，请重新选择"); searchByPrice(); } } //新增商品 public void addGoods(){ System.out.println("请输入商品名称："); String goodsName=scanner.next(); System.out.println("请输入商品价格："); double goodsPrice=scanner.nextDouble(); System.out.println("请输入品牌"); String brandsName=scanner.next(); int brandsNum; if(brandsDAO.findBranch(brandsName)){ brandsNum=brandsDAO.findByName(brandsName).getBrandsNum(); } else{ brandsNum=brandsDAO.brandsNumbers()+1; Brands brands=new Brands(brandsName,brandsNum); brandsDAO.addBranch(brands); } System.out.println("请输入商品类型"); String goodsCate=scanner.next(); Goods goods=new Goods(goodsName,goodsPrice,0,goodsCate,brandsNum, UUID.randomUUID().toString()); goodsDAO.addGoods(goods); System.out.println("商品添加成功"); controlGoods(); } //改变价格 public void changePrice(){ System.out.println("--------修改价格------"); brandsDAO.findAll(); System.out.println("请输入要查询的品牌编号："); String brandsNum1=scanner.next(); if(isNumeric(brandsNum1)) { int brandsNum=Integer.parseInt(brandsNum1); List<Goods> temporlist = goodsDAO.searchByBranchId(brandsNum); if (temporlist == null) { System.out.println("没有该品牌的商品"); changePrice(); } for (int i = 0; i < temporlist.size(); i++) { System.out.println("序号" + (i + 1) + "\t" + "商品名字：" + temporlist.get(i).getGoodsName() + "\t价格" + temporlist.get(i).getGoodsPrice() + "元"); } System.out.println("请输入要修改价格的商品ID或输入0返回上一层菜单。"); String choose1 = scanner.next(); if(isNumeric(choose1)) { int choose=Integer.parseInt(choose1); if (choose == 0) { controlGoods(); } else if(choose<=temporlist.size()) { System.out.println("请输入要修改的价格："); double price = scanner.nextDouble(); System.out.println("是否确定修改价格：是/否"); String endChoose = scanner.next(); if (endChoose.equals("是")) { goodsDAO.modify(temporlist.get(choose - 1).getGoodsNum(), price); System.out.println("价格修改完成"); controlGoods(); } else { controlGoods(); } } else{ System.out.println("输入序号超过边界，请重新输入"); changePrice(); } } else{ System.out.println("输入错误符号，请重新输入"); changePrice(); } } else{ System.out.println("输入错误符号，请重新输入"); changePrice(); } } //删除商品 public void deleteGoods(){ System.out.println("--------删除商品------"); brandsDAO.findAll(); System.out.println("请输入要查询的品牌编号："); String brandsNum2=scanner.next(); if(isNumeric(brandsNum2)) { int brandsNum=Integer.parseInt(brandsNum2); List<Goods> temporlist = goodsDAO.searchByBranchId(brandsNum); if (temporlist == null) { System.out.println("没有该品牌的商品"); deleteGoods(); } for (int i = 0; i < temporlist.size(); i++) { System.out.println("序号" + (i + 1) + "\t" + "商品名字：" + temporlist.get(i).getGoodsName()); } System.out.println("请输入要删除的商品ID或输入0返回上一层菜单。"); String choose1 = scanner.next(); if(isNumeric(choose1)) { int choose=Integer.parseInt(choose1); if (choose == 0) { controlGoods(); } else if(choose<=temporlist.size()){ System.out.println("是否确定删除：是/否"); String endChoose = scanner.next(); if (endChoose.equals("是")) { int brandsNum1 = temporlist.get(choose - 1).getBrandsNum(); goodsDAO.delete(temporlist.get(choose - 1).getGoodsNum()); System.out.println("删除成功"); if (goodsDAO.searchByBranchId(brandsNum1) == null) { brandsDAO.deleteBrands(brandsNum1); brandsDAO.moveBrandsNum(brandsNum1); for (int i = brandsNum1; i <= brandsDAO.brandsNumbers(); i++) goodsDAO.changeByBranchId(i + 1); } controlGoods(); } else { controlGoods(); } } else{ System.out.println("输入序号超过边界，请重新输入"); deleteGoods(); } } else{ System.out.println("输入错误符号，请重新输入"); deleteGoods(); } } else{ System.out.println("输入错误符号，请重新输入"); deleteGoods(); } } public boolean isNumeric(String str){ for (int i = str.length();--i>=0;){ if (!Character.isDigit(str.charAt(i))){ return false; } } return true; }}

注：以上代码部分内部类的导入未填写
还需要一个测试类运行
暂且略过

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