【JAVA学习笔记】72 - 满汉楼

项目代码

https://github.com/yinhai1114/Java_Learning_Code/tree/main/IDEA_Chapter26

一、需求说明

满汉楼项目功能多，界面复杂，涉及到复杂的awt和swing技术和事件编程，做如下调整:

1.去掉界面和事件处理(工作中使用很少)，使用控制台界面

2.完成满汉楼项目的登录、订座、点餐和结账、查看账单等功能.

3.在实际工作中，独立完成项目新功能非常重要，这是锻炼编程能力和思想的重要途径

1.用户登录

2.显示餐桌的状态

3.预定

4.显示菜品

5.点餐

6.查看账单

7.结账

二、项目设计

三、功能实现

1.显示主菜单、二级菜单和退出系统功能

public void mainMenu(){
        while (loop){
            System.out.println("==============满汉楼===============");
            System.out.println("\t\t1.登录满汉楼");
            System.out.println("\t\t2.退出满汉楼");
            System.out.println("请输入你的选择");
            key = Utility.readString(1);
            switch (key){
                case "1":
                    System.out.println("输入员工号:");
                    String id = Utility.readString(50);
                    System.out.println("输入密 码");
                    String pwd = Utility.readString(50);
                    //到数据库去判断
                    if("123".equals(pwd)){
                        System.out.println("===========登录成功===========");
                        while(loop){
                            System.out.println("=========满汉楼(二级菜单)==========");
                            System.out.println("\t\t1 显示餐桌状态");
                            System.out.println("\t\t2 预定餐桌状态");
                            System.out.println("\t\t3 显示所有菜品");
                            System.out.println("\t\t4 点餐服务");
                            System.out.println("\t\t5 查看账单");
                            System.out.println("\t\t6 结账");
                            System.out.println("\t\t9 退出满汉楼");
                            key = Utility.readString(1);
                            switch (key){
                                case "1":
                                    System.out.println("显示餐桌状态");
                                    break;
                                case "2":
                                    System.out.println("预定餐桌");
                                    break;
                                case "3":
                                    System.out.println("显示所有菜品");
                                    break;
                                case "4":
                                    System.out.println("点餐服务");
                                    break;
                                case "5":
                                    System.out.println("查看账单");
                                    break;
                                case "6":
                                    System.out.println("结账");
                                    break;
                                case "9":
                                    loop = false;
                                    break;
                                default:
                                    System.out.println("你的输入有误 请重新输入");
                            }
                        }
                    }else{
                        System.out.println("===========登录失败===========");
                    }
                    break;
                case "2":
                    System.out.println("2.退出满汉楼");
                    loop = false;
                    break;
                default:
                    System.out.println("输入错误错误");
            }

        }
        System.out.println("退出满汉楼");
    }

2.用户登录

CREATE DATABASE mhl
#用户表
CREATE TABLE employee (
	id INT PRIMARY KEY AUTO_INCREMENT, #自增
	empId VARCHAR(50) UNIQUE NOT NULL DEFAULT '',#员工号
	pwd CHAR(32) NOT NULL DEFAULT '',#密码md5
	NAME VARCHAR(50) NOT NULL DEFAULT '',#姓名
	job VARCHAR(50) NOT NULL DEFAULT '' #岗位
)CHARSET=utf8; 

DROP TABLE employee
#添加测试数据
INSERT INTO employee VALUES(NULL, '6668612', MD5('123456'), '张三丰', '经理');
INSERT INTO employee VALUES(NULL, '6668622', MD5('123456'),'小龙女', '服务员');
INSERT INTO employee VALUES(NULL, '6668633', MD5('123456'), '张无忌', '收银员');
INSERT INTO employee VALUES(NULL, '666666', MD5('123456'), '老韩', '经理');
SELECT * FROM employee

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 * 该类调用EmployeeDAO对象完成对表的各种操作
 */
public class EmployeeService {

    //定义一个EmployeeDAO属性
    private EmployeeDAO employeeDAO = new EmployeeDAO();

    //方法 根据empId和pwd返回一个Employee对象
    public Employee getEmployeeByIdAndPwd(String empId,String pwd){

        return employeeDAO.querySingle("select * from employee where empId=? and pwd=md5(?)", Employee.class, empId, pwd);
    }
}

该服务并不直接修改数据库，而是通过DAO调用JDBCDruid修改数据库

             if(employee != null){
                        System.out.println("===========登录成功(" + employee.getName() + ")===========");
                        while(loop){

3.显示餐桌状态

1.创建新的餐位表

2.domain里设计一个类对应该表

3.DAO类对表crud

4.service调用DAO修改

-- 创建diningTable 表(id, state , orderName, orderTel ....)

CREATE TABLE diningTable (
	id INT PRIMARY KEY AUTO_INCREMENT, #自增, 表示餐桌编号
	state VARCHAR(20) NOT NULL DEFAULT '',#餐桌的状态
	orderName VARCHAR(50) NOT NULL DEFAULT '',#预订人的名字
	orderTel VARCHAR(20) NOT NULL DEFAULT ''
)CHARSET=utf8; 
#测试数据
INSERT INTO diningTable VALUES(NULL, '空','','');
INSERT INTO diningTable VALUES(NULL, '空','','');
INSERT INTO diningTable VALUES(NULL, '空','','');
SELECT * FROM diningTable

2.设计一个类对应该表

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 * 一个javabean 和diningTable表对应
 * 	id INT PRIMARY KEY AUTO_INCREMENT, #自增, 表示餐桌编号
 * 	state VARCHAR(20) NOT NULL DEFAULT '',#餐桌的状态
 * 	orderName VARCHAR(50) NOT NULL DEFAULT '',#预订人的名字
 * 	orderTel VARCHAR(20) NOT NULL DEFAULT ''
 */

public class DiningTable {
    private Integer id;
    private String state;
    private String orderName;
    private String orderTel;

    public DiningTable() {
    }

    public DiningTable(Integer id, String state, String orderName, String orderTel) {
        this.id = id;
        this.state = state;
        this.orderName = orderName;
        this.orderTel = orderTel;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getOrderName() {
        return orderName;
    }

    public void setOrderName(String orderName) {
        this.orderName = orderName;
    }

    public String getOrderTel() {
        return orderTel;
    }

    public void setOrderTel(String orderTel) {
        this.orderTel = orderTel;
    }

    @Override
    public String toString() {
        return id + "\t\t\t" + state;
    }
}

public class DiningTableService {
    //定义一个DiningTableDAO对象
    private DiningTableDAO diningTableDAO = new DiningTableDAO();

    //返回所有餐桌的信息
    public List<DiningTable> list(){

        return diningTableDAO.queryMulti("select id,state from diningTable", DiningTable.class);
    }
}

4.订座

功能说明如果该餐桌处于已经预定或者就餐状态，给出提示

1.在DiningTableService内添加对应方法

//根据id 查询对应的DiningTable对象 如果返回null 表示id编号对应餐桌不存在
    public DiningTable getDiningTableById(int id){

        //把sql语句放到查询分析器去测试一下
        return diningTableDAO.querySingle("select * from diningTable where id = ?",DiningTable.class,id);
    }

    //如果餐桌可以预定 调用方法对其状态进行更新
    public boolean orderDiningTable(int id,String orderName,String orderTel) {
        int dml =
                diningTableDAO.dml("update diningTable set state = '已经" +
                        "预定',orderName = ?,orderTel=? where id = ?", orderName, orderTel, id);
        return dml > 0;
    }

2.在view内添加判断用户输入方法，并在对应阶段调用该方法即可

//预定餐桌
    public void orderDiningTable(){
        System.out.println("=========预定餐桌==========");
        System.out.println("请选择要预定的餐桌的编号(-1退出)");
        int orderId = Utility.readInt();
        if(orderId == -1){
            return;
        }
        DiningTable diningTable = diningTableService.getDiningTableById(orderId);
        if(diningTable == null){ //说明不存在
            System.out.println("==========该餐桌不存在=========");
            return;
        }
        char key = Utility.readConfirmSelection();//输入Y/N
        if (key == 'Y'){
            //要预定就调用方法 如果为null该对象不存在

            if(!("空".equals(diningTable.getState()))){
                System.out.println("==========该餐桌已被预定或就餐中=========");
                return;
            }
            System.out.println("预订人的名字:");
            String orderName = Utility.readString(50);
            System.out.println("预订人的电话:");
            String orderTel = Utility.readString(50);

            if(diningTableService.orderDiningTable(orderId,orderName,orderTel)){
                System.out.println("预定餐桌成功");

            }else{
                System.out.println("预定餐桌失败");
            }
            //过关斩将
        }else{
            System.out.println("=========取消预定餐桌==========");
        }
    }

5.显示菜品

1.需要创建一个新的菜单表

2.需要在java内建立domain类

3.需要创建菜单的DAO类

4.需要service组织sql并调用DAO

-- 创建menu表(id, name, type, price)
#菜谱
CREATE TABLE menu (
	id INT PRIMARY KEY AUTO_INCREMENT, #自增主键，作为菜谱编号(唯一)
	NAME VARCHAR(50) NOT NULL DEFAULT '',#菜品名称
	TYPE VARCHAR(50) NOT NULL DEFAULT '', #菜品种类
	price DOUBLE NOT NULL DEFAULT 0#价格
)CHARSET=utf8; 
#测试数据
INSERT INTO menu VALUES(NULL, '八宝饭', '主食', 10);
INSERT INTO menu VALUES(NULL, '叉烧包', '主食', 20);
INSERT INTO menu VALUES(NULL, '宫保鸡丁', '热菜', 30);
INSERT INTO menu VALUES(NULL, '山药拨鱼', '凉菜', 14);
INSERT INTO menu VALUES(NULL, '银丝卷', '甜食', 9);
INSERT INTO menu VALUES(NULL, '水煮鱼', '热菜', 26);
INSERT INTO menu VALUES(NULL, '甲鱼汤', '汤类', 100);
INSERT INTO menu VALUES(NULL, '鸡蛋汤', '汤类', 16);

2.在java内创建domain的Menu类对应表的对象

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 * 该javabean和 menu 表对应
 *  id INT PRIMARY KEY AUTO_INCREMENT, #自增, 表示餐桌编号
 * 	state VARCHAR(20) NOT NULL DEFAULT '',#餐桌的状态
 * 	orderName VARCHAR(50) NOT NULL DEFAULT '',#预订人的名字
 * 	orderTel VARCHAR(20) NOT NULL DEFAULT ''
 */
public class Menu {
    private Integer id;
    private String name;
    private String type;
    private Double price;

    public Menu(){//无参构造器

    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Menu(Integer id, String name, String type, Double price) {
        this.id = id;
        this.name = name;
        this.type = type;
        this.price = price;
    }
}

3.DAO继承BasicDAO

4.service类组织sql调用DAO

public class MenuService {
    private MenuDAO menuDAO = new MenuDAO();

    //返回所有的菜品
    public List<Menu> list(){
        return menuDAO.queryMulti("select * from menu",Menu.class);
    }

}

在view内编写方法调用service类的方法

public void listMenu(){
        List<Menu> list = menuService.list();
        System.out.println("\n菜品编号\t\t菜品名\t\t类别\t\t价格");
        for (Menu menu : list) {
            System.out.println(menu);
        }
        System.out.println("=========显示完毕==========");
}

6.点餐

功能说明要求对餐桌号，菜品编号，做合理性校验，如果不合理，给出提示信息

餐桌号菜品号检验是否合理，点餐成功，需要修改餐桌状态，生成账单

1.需要创建一个新的账单表

2.需要在java内建立domain类

3.需要创建菜单的DAO类

4.需要service组织sql并调用DAO

1.新建账单表


#增加表 bill 账单表(id, billId, menuId, nums, billDate, money, state, diningTableId )
#账单流水, 考虑可以分开结账, 并考虑将来分别统计各个不同菜品的销售情况
CREATE TABLE bill (
	id INT PRIMARY KEY AUTO_INCREMENT, #自增主键
	billId VARCHAR(50) NOT NULL DEFAULT '',#账单号可以按照自己规则生成 UUID
	menuId INT NOT NULL DEFAULT 0,#菜品的编号, 也可以使用外键
	nums INT NOT NULL DEFAULT 0,#份数
	money DOUBLE NOT NULL DEFAULT 0, #金额
	diningTableId INT NOT NULL DEFAULT 0, #餐桌
	billDate DATETIME NOT NULL ,#订单日期
	state VARCHAR(50) NOT NULL DEFAULT '' # 状态 '未结账' , '已经结账', '挂单','现金','支付宝','坏账'
)CHARSET=utf8;

SELECT * FROM bill;

2.创建domain类 javabean

/**
 * @author 银小海
 * @version 1.0
 * @email yinhai14@qq.com
 * 	id INT PRIMARY KEY AUTO_INCREMENT, #自增主键
 * 	billId VARCHAR(50) NOT NULL DEFAULT '',#账单号可以按照自己规则生成 UUID
 * 	menuId INT NOT NULL DEFAULT 0,#菜品的编号, 也可以使用外键
 * 	nums INT NOT NULL DEFAULT 0,#份数
 * 	money DOUBLE NOT NULL DEFAULT 0, #金额
 * 	diningTableId INT NOT NULL DEFAULT 0, #餐桌
 * 	billDate DATETIME NOT NULL ,#订单日期
 * 	state VARCHAR(50) NOT NULL DEFAULT '' # 状态 '未结账' , '已经结账', '挂单','现
 */
public class Bill {
    private Integer id;
    private String billId;
    private Integer menuId;
    private Integer nums;
    private Double money;
    private Integer diningTableId;
    private Date billDate;
    private String state;

    public Bill() {
    }

    public Bill(Integer id, String billId, Integer menuId, Integer nums, Double money, Integer diningTableId, Date billDate, String state) {
        this.id = id;
        this.billId = billId;
        this.menuId = menuId;
        this.nums = nums;
        this.money = money;
        this.diningTableId = diningTableId;
        this.billDate = billDate;
        this.state = state;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getBillId() {
        return billId;
    }

    public void setBillId(String billId) {
        this.billId = billId;
    }

    public Integer getMenuId() {
        return menuId;
    }

    public void setMenuId(Integer menuId) {
        this.menuId = menuId;
    }

    public Integer getNums() {
        return nums;
    }

    public void setNums(Integer nums) {
        this.nums = nums;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }

    public Integer getDiningTableId() {
        return diningTableId;
    }

    public void setDiningTableId(Integer diningTableId) {
        this.diningTableId = diningTableId;
    }

    public Date getBillDate() {
        return billDate;
    }

    public void setBillDate(Date billDate) {
        this.billDate = billDate;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    @Override
    public String toString() {
        return  id +
                "\t\t" + menuId +
                "\t\t\t" + nums +
                "\t\t\t" + money +
                "\t" + diningTableId +
                "\t\t" + billDate +
                "\t\t" + state ;
    }
}

3.编写账单服务类该方法还需要其他服务类辅助因此也需要再其他服务类内增加方法

public class BillService {
    //定义BillDAO属性
    private BillDAO billDAO = new BillDAO();

    //需要定义另一个service获得菜单用来计算金额
    private MenuService menuService = new MenuService();

    //需要定义另一个service更改餐桌的状态
    private DiningTableService diningTableService = new DiningTableService();

    //编写点餐的方法
    //1.生成账单 2. 需要更新对应餐桌状态 3.如果成功返回true 否则返回false
    public boolean orderMenu(int menuId,int nums,int diningTableId){
        //生成一个账单号UUID
        String billUUID = UUID.randomUUID().toString();

        //将这个账单生成到bill表 要直接计算账单的金额 也就是获得menu对象
        int dml = billDAO.dml("insert into bill values" +
                "(null,?,?,?,?,?,now(),'未结账')", billUUID, menuId, nums, menuService.getMenuId(menuId).getPrice() * nums, diningTableId);
        if(dml <= 0){
            return false;
        }

        //需要更新餐桌状态
        return diningTableService.updateDiningTableState(diningTableId,"就餐中");

    }
}

4.在view调用该服务类

 //完成点餐
    public void orderMenu() {
        System.out.println("==============点餐服务============");
        System.out.print("请输入点餐的桌号(-1退出): ");
        int orderDiningTableId = Utility.readInt();
        if (orderDiningTableId == -1) {
            System.out.println("==============取消点餐============");
            return;
        }
        System.out.print("请输入点餐的菜品号(-1退出): ");
        int orderMenuId = Utility.readInt();
        if (orderMenuId == -1) {
            System.out.println("==============取消点餐============");
            return;
        }
        System.out.print("请输入点餐的菜品量(-1退出): ");
        int orderNums = Utility.readInt();
        if (orderNums == -1) {
            System.out.println("==============取消点餐============");
            return;
        }

        //验证餐桌号是否存在.
        DiningTable diningTable = diningTableService.getDiningTableById(orderDiningTableId);
        if (diningTable == null) {
            System.out.println("==============餐桌号不存在============");
            return;
        }
        //验证菜品编号
        Menu menu = menuService.getMenuId(orderMenuId);
        if (menu == null) {
            System.out.println("==============菜品号不存在============");
            return;
        }

        //点餐
        if (billService.orderMenu(orderMenuId, orderNums, orderDiningTableId)) {
            System.out.println("==============点餐成功============");
        } else {
            System.out.println("==============点餐失败============");
        }
    }

7.查看账单

1.billDao获得bill对象

2.service编写方法调用billDAO获得bill对象

3.view调用该service方法

2.service调用DAO获得list数组

public List<Bill> list(){
        return billDAO.queryMulti("select * from bill",Bill.class);
    }

3.view显示账单

public void listBill() {
        List<Bill> bills = billService.list();
        System.out.println("\n编号\t\t菜品号\t\t菜品量\t\t金额\t\t桌号\t\t日期\t\t\t\t\t\t\t状态");
        for (Bill bill : bills) {
            System.out.println(bill);
        }
        System.out.println("==============显示完毕============");
    }

8.结账

(1)对餐桌号进行校验 (2)修改bill表的state (3)修改diningTable信息 (4)不需要增加表和类

1.在 service类内查看是否有未结账或者餐桌是否存在（校验）

//查看某个产值是否有未结账的账单
    public boolean hasPayBillByDiningTableId(int diningTableId) {

        Bill bill =
                billDAO.querySingle("SELECT * FROM bill WHERE diningTableId=? AND state = '未结账' LIMIT 0, 1", Bill.class, diningTableId);
        return bill != null;
    }

    //完成结账[如果餐桌存在，并且该餐桌有未结账的账单]
    //如果成功，返回true, 失败返回 false
    public boolean payBill(int diningTableId, String payMode) {

        //如果这里使用事务的话，需要用ThreadLocal来解决 , 框架中比如mybatis 提供了事务支持
        //1. 修改bill表
        int update = billDAO.dml("update bill set state=? where diningTableId=? and state='未结账'", payMode, diningTableId);

        if(update <= 0) { //如果更新没有成功，则表示失败...
            return false;
        }
        //2. 修改diningTable表
        //注意：不要直接在这里操作，而应该调用DiningTableService 方法,完成更新，体现各司其职

        if(!diningTableService.updateDiningTableToFree(diningTableId, "空")) {
            return false;
        }
        return true;

    }

2.修改diningTable为空闲

//需要提供一个更新餐桌状态为空闲的方法
    public boolean updateDiningTableToFree(int id,String state){
        int dml = diningTableDAO.dml("update diningTable set state=?,orderName = '',orderTel = '' where id=?", state, id);
        return dml > 0;
    }

3.在view内定义方法调用service方法

//完成结账
    public void payBill() {
        System.out.println("==============结账服务============");
        System.out.print("请选择要结账的餐桌编号(-1退出): ");
        int diningTableId = Utility.readInt();
        if (diningTableId == -1) {
            System.out.println("=============取消结账============");
            return;
        }
        //验证餐桌是否存在
        DiningTable diningTable = diningTableService.getDiningTableById(diningTableId);
        if (diningTable == null) {
            System.out.println("=============结账的餐桌不存在============");
            return;
        }
        //验证餐桌是否有需要结账的账单
        if (!billService.hasPayBillByDiningTableId(diningTableId)) {
            System.out.println("=============该餐位没有未结账账单============");
            return;
        }
        System.out.print("结账方式(现金/支付宝/微信)回车表示退出: ");
        String payMode = Utility.readString(20, "");//说明如果回车，就是返回 ""
        if ("".equals(payMode)) {
            System.out.println("=============取消结账============");
            return;
        }
        char key = Utility.readConfirmSelection();
        if (key == 'Y') { //结账

            //调用我们写的方法
            if (billService.payBill(diningTableId, payMode)) {
                System.out.println("=============完成结账============");
            } else {
                System.out.println("=============结账失败============");
            }

        } else {
            System.out.println("=============取消结账============");
        }
    }

四、进行代码拓展

1.多表查询的需求

我们可以再增加一个MultableBean，跟多张表进行映射，所以要有一个MultableBeanDAO，然后调用该DAO

另一个方案

DBUtils数据库连接池多表连接查询_利用数据池连接数据库多个表-CSDN博客

1.创建bean表

public class MultiTableBean {
    private Integer id;
    private String billId;
    private Integer menuId;
    private Integer nums;
    private Double money;
    private Integer diningTableId;
    private Date billDate;
    private String state;
    //增加一个来自menu表的列 name
    //思考 这里的属性名是否一定要和表的列名保持一致.
    //答: 可以不一致，但是需要sql做相应的修改, 规范需要保持一致.
    private String name;
    //增加来自menu表的列 price
    private Double price;//默认值 nulll

    public MultiTableBean() {
        System.out.println("反射调用....");
    }

//    public MultiTableBean(Integer id, String billId, Integer menuId, Integer nums, Double money, Integer diningTableId, Date billDate, String state, String name, Double price) {
//        this.id = id;
//        this.billId = billId;
//        this.menuId = menuId;
//        this.nums = nums;
//        this.money = money;
//        this.diningTableId = diningTableId;
//        this.billDate = billDate;
//        this.state = state;
//        this.name = name;
//        this.price = price;
//    }

    //给price生成setter 和 getter

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }


    //给name生成setter 和 getter


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getBillId() {
        return billId;
    }

    public void setBillId(String billId) {
        this.billId = billId;
    }

    public Integer getMenuId() {
        return menuId;
    }

    public void setMenuId(Integer menuId) {
        this.menuId = menuId;
    }

    public Integer getNums() {
        return nums;
    }

    public void setNums(Integer nums) {
        this.nums = nums;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }

    public Integer getDiningTableId() {
        return diningTableId;
    }

    public void setDiningTableId(Integer diningTableId) {
        this.diningTableId = diningTableId;
    }

    public Date getBillDate() {
        return billDate;
    }

    public void setBillDate(Date billDate) {
        this.billDate = billDate;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    @Override
    public String toString() {
        return  id +
                "\t\t" + menuId +
                "\t\t\t" + nums +
                "\t\t\t" + money +
                "\t" + diningTableId +
                "\t\t" + billDate +
                "\t\t" + state +
                "\t\t" + name +
                "\t\t" + price;
    }
}

2.创建dao类

3. view中调用

 public void listBill() {
        /*//单表查询
        List<Bill> bills = billService.list();
        System.out.println("\n编号\t\t菜品号\t\t菜品量\t\t金额\t\t桌号\t\t日期\t\t\t\t\t\t\t状态");
        for (Bill bill : bills) {
            System.out.println(bill);
        }
        System.out.println("==============显示完毕============");
        */
        //多表查询
        List<MultiTableBean> multiTableBeans = billService.list2();
        System.out.println("\n编号\t\t菜品号\t\t菜品量\t\t金额\t\t桌号\t\t日期\t\t\t\t\t\t\t状态\t\t菜品名\t\t价格");
        for (MultiTableBean bill : multiTableBeans) {
            System.out.println(bill);
        }
        System.out.println("==============显示完毕============");
    
    }

根据需要增加需要的字段