JAVA Class14

Posted 2020-10-30 Observer

学习内容：

分包（分层）：

通过定义不同的包来将工程的各个功能细分，一般包含如下几部分：

view层作用: 视图层,即项目中的界面

controller层作用: 控制层, 获取界面上的数据,为界面设置数据; 将要实现的功能交给业务层处理

service层作用: 业务层, 功能的实现, 与controller控制层和数据访问层DAO交互, 将对数据库的操作交给DAO数据访问层来处理

dao层作用: 数据访问层, 用来操作数据库表的数据

db数据库: 这里指mysql

domain 实体包: 存放JavaBean

tools工具包:存放项目中使用到的工具类

test 测试包: 存放项目功能测试的代码

编写顺序：

以下是一个简单的超市管理系统：

1.tools包，创建工具方法，建立数据库连接，关闭数据库连接

package com.store.tools;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class DButil {
    private DButil() {};
    public static Connection getConn() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url="jdbc:mysql://127.0.0.1:3306/demo_JDBC?characterEncoding=UTF-8";
            String username="root";
            String password="123456";
            Connection conn=DriverManager.getConnection(url,username,password);
            return conn;
        } catch (Exception e) {
            throw new RuntimeException(e+"数据库连接失败");
        }
    }
    public static void close(Statement sta,Connection conn) {
        if(sta!=null) {
            try {
                sta.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if(conn!=null) {
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(ResultSet rs,Statement sta,Connection conn) {
        if(rs!=null) {
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        close(sta,conn);
    } 
}

2.domain包，创建实体类，定义Store类的构造方法、属性等

package com.store.domain;
public class Store {
    private int sid;
    private String brands;
    private int size;
    private double price;
    private int counts;
    public Store(){};
    public Store(int sid,String brands,int size,double price,int counts) {
        this.sid = sid;
        this.brands = brands;
        this.size = size;
        this.price = price;
        this.counts = counts;
    }
    public int getSid() {
        return sid;
    }
    public void setSid(int sid) {
        this.sid = sid;
    }
    public String getBrands() {
        return brands;
    }
    public void setBrands(String brands) {
        this.brands = brands;
    }
    public int getSize() {
        return size;
    }
    public void setSize(int size) {
        this.size = size;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    public int getCounts() {
        return counts;
    }
    public void setCounts(int counts) {
        this.counts = counts;
    }
}

3.view包，创建操作页面

package com.store.view;
import java.util.ArrayList;
import java.util.Scanner;
import com.store.controller.StoreController;
import com.store.domain.Store;
import com.store.tools.DButil;
public class StoreView {
    StoreController storeController = new StoreController();
    Scanner sc = new Scanner(System.in);
    public void run() {
        while(true) {
        System.out.println("------------商城管理系统------------");
        System.out.println("1.查询所有商品信息");
        System.out.println("2.新增商品信息");
        System.out.println("3.修改商品信息");
        System.out.println("4.删除商品信息");
        System.out.println("5.退出");
        System.out.println("请选择功能序号：");
        int choose = sc.nextInt();
            switch(choose) {
                case 1:
                    find();
                    break;
                case 2:
                    find();
                    add();
                    break;
                case 3:
                    find();
                    update();
                    break;
                case 4:
                    find();
                    delete();
                    break;
                case 5:
                    System.out.println("欢迎下次使用！");
                    return;
                default:
                    System.out.println("选择有误，请重新选择功能！");
            }
        }
    }
    public  void find() {
        ArrayList<Store> list = storeController.find();
        System.out.println("商品编号\\t商品品牌\\t商品尺寸\\t商品价格\\t商品数量");
        for(int i=0;i<list.size();i++) {
            System.out.printf("%d\\t%s\\t%d\\t%f\\t%d%n"
            ,list.get(i).getSid(),list.get(i).getBrands(),list.get(i).getSize(),list.get(i).getPrice(),list.get(i).getCounts());
        }
    }
    public  void add() {
        System.out.println("请输入商品品牌：");
        String brands = sc.next();
        System.out.println("请输入商品尺寸");
        int size = sc.nextInt();
        System.out.println("请输入商品价格：");
        double price = sc.nextDouble();
        System.out.println("请输入商品数量：");
        int counts= sc.nextInt();    
        Store store = new Store();
        store.setBrands(brands);
        store.setSize(size);
        store.setPrice(price);
        store.setCounts(counts);
        storeController.add(store);
    }

　　public  void update() {
    　　System.out.println("请输入要修改商品的ID");
    　　int sid = sc.nextInt();
    　　System.out.println("请输入修改后的商品品牌：");
   　　 String brands = sc.next();
   　　 System.out.println("请输入修改后的商品尺寸");
    　　int size = sc.nextInt();
    　　System.out.println("请输入修改后的商品价格：");
    　　double price = sc.nextDouble();
    　　System.out.println("请输入修改后的商品数量：");
    　　int counts= sc.nextInt();    
    　　Store store = new Store();
    　　store.setSid(sid);
    　　store.setBrands(brands);
    　　store.setSize(size);
    　　store.setPrice(price);
    　　store.setCounts(counts);
    　　storeController.update(store);
   }

　　public  void delete() {
    　　System.out.println("请输入要删除的商品的ID");
    　　int sid = sc.nextInt();
    　　Store store = new Store();
    　　store.setSid(sid);
    　　storeController.delete(store);
    }
}

4.dao包，定义操作数据库的方法

package com.store.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import com.store.domain.Store;
import com.store.tools.DButil;
public class StoreDAO {
    public ArrayList<Store> find() {
        try {
            Connection conn = DButil.getConn();
            Statement sta = conn.createStatement();
            String sql = "select * from store";
            ResultSet rs = sta.executeQuery(sql);
            ArrayList<Store> store = new ArrayList<Store>();
            while(rs.next()) {
                Store s = new Store(rs.getInt("sid"),rs.getString("brands"),rs.getInt("size"),rs.getDouble("price"),rs.getInt("counts"));
                store.add(s);
            }
            DButil.close(rs, sta, conn);
            return store;
        } catch (Exception e) {
            System.out.println(e);
            throw new RuntimeException("商品查询失败");
        }    
    }
    public int add(Store store) {
        try {
            Connection conn = DButil.getConn();
            String sql = "insert into store(brands,size,price,counts) values(?,?,?,?)";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, store.getBrands());
            ps.setInt(2, store.getSize());
            ps.setDouble(3, store.getPrice());
            ps.setInt(4,store.getCounts());
            int row = ps.executeUpdate();
            DButil.close(ps, conn);
            return row;
        } catch (Exception e) {
            System.out.println(e);
            throw new RuntimeException("商品添加失败");
        }
    }
    public int update(Store store) {
        try {
            Connection conn = DButil.getConn();
            String sql = "update store set brands=?,size=?,price=?,counts=? where sid=?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setString(1, store.getBrands());
            ps.setInt(2, store.getSize());
            ps.setDouble(3, store.getPrice());
            ps.setInt(4,store.getCounts());
            ps.setInt(5,store.getSid());
            int row = ps.executeUpdate();
            DButil.close(ps, conn);
            return row;
        } catch (Exception e) {
            System.out.println(e);
            throw new RuntimeException("商品修改失败");
        }
    }
    public int delete(Store store) {
        try {
            Connection conn = DButil.getConn();
            String sql = "delete from store where sid=?";
            PreparedStatement ps = conn.prepareStatement(sql);
            ps.setInt(1, store.getSid());
            int row = ps.executeUpdate();
            DButil.close(ps, conn);
            return row;
        } catch (Exception e) {
            System.out.println(e);
            throw new RuntimeException("商品删除失败");
        }
    }
}

5.service包，业务类，实现controller与dao包间的数据交换

package com.store.service;
import java.util.ArrayList;
import com.store.dao.StoreDAO;
import com.store.domain.Store;
public class StoreService {
    private StoreDAO storeDAO = new StoreDAO();
    public ArrayList<Store>    find(){
        return storeDAO.find();
    }
    public int add(Store store) {
        return storeDAO.add(store);
    }
    public int update(Store store) {
        return storeDAO.update(store);
    }
    public int delete(Store store) {
        return storeDAO.delete(store);
    }
}

6.controller包，捕获view包传递的数据

package com.store.controller;
import java.util.ArrayList;
import com.store.domain.Store;
import com.store.service.StoreService;
public class StoreController {
    private StoreService storeService = new StoreService();
    public ArrayList<Store>    find(){
        return storeService.find();
    }
    public  void add(Store store) {
        int mes =  storeService.add(store);
        if(mes>0) {
            System.out.println("商品添加成功");
        }else {
            System.out.println("商品添加失败");
        }
    }
    public  void update(Store store) {
        int mes =  storeService.update(store);
        if(mes>0) {
            System.out.println("商品修改成功");
        }else {
            System.out.println("商品修改失败");
        }
    }
    public  void delete(Store store) {
        int mes =  storeService.delete(store);
        if(mes>0) {
            System.out.println("商品删除成功");
        }else {
            System.out.println("商品删除失败");
        }
    }
}

7.test包，测试功能

package com.store.test;
import com.store.view.StoreView;
public class TestStore {
    public static void main(String[] args) {
        new StoreView().run();
    }
}