JAVA学习笔记（十四）

项目中常见的分包（分层）

　　当程序规模小的时候，可以一个人全部完成；但当程序规模大的时候，一个人难以完成，这时候，要采用多人合作的方式来完成程序的开发。

　　通过用户注册功能来讲解一下项目中常见的分包（分层）。如下图

view层作用：视图层，控制项目中主界面显示的内容。

controller层：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：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：数据访问层, 用来操作数据库表的数据。

DB数据库：这里指的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。

下面是一个Store项目，用来练习项目的分包

view层

package com.oracle.view;

import java.sql.PreparedStatement;
import java.util.ArrayList;
import java.util.Scanner;

import com.oracle.controller.StoreController;
import com.oracle.domain.Store;

public class StoreView {
    StoreController storeController=new StoreController();
    Scanner sc=new Scanner(System.in);
            public void run() {
                Scanner sc=new Scanner(System.in);
                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("请输入您的选择");
                    int choose=sc.nextInt();
                    switch(choose) {
                    case 1:  find();
                        break;
                    case 2: add();
                        break;
                    case 3: update();
                        break;
                    case 4:del();
                        break;
                    case 5:
                        return;
                    default:
                        break;
                    }
                    }
                }
            //查询
            public void find() {
                
                ArrayList<Store> list=storeController.find();
                System.out.println("商品编号\t商品名称\t商品大小\t商品价格\t商品数量");
                for(int i=0;i<list.size();i++) {
                    System.out.println(list.get(i).getSid()+"\t"+list.get(i).getBrands()+"\t"
                            +list.get(i).getSize()+"\t"+list.get(i).getPrice()+"\t"
                            +list.get(i).getCounts());
                }
            }
            //添加
            public void add() {
                Store store=new Store();
                System.out.println("请输入您要添加的商品名称:");
                String name=sc.next();
                store.setBrands(name);
                System.out.println("请输入您要添加的商品大小:");
                int size=sc.nextInt();
                store.setSize(size);
                System.out.println("请输入您要添加的商品价格:");
                Double price=sc.nextDouble();
                store.setPrice(price);
                System.out.println("请输入您要添加的商品数量:");
                int counts=sc.nextInt();
                store.setCounts(counts);
                String mes=storeController.add(store);
                System.out.println(mes);
            }
            public void update() {
                Store store=new Store();
                System.out.println("请选择您要修改的产品id");
                int id=sc.nextInt();
                System.out.println("请输入修改后的品牌名");
                String name=sc.next();
                System.out.println("请输入修改后的尺寸");
                Double size=sc.nextDouble();
                System.out.println("请输入修改后的价格");
                Double price=sc.nextDouble();
                System.out.println("请输入修改后的库存");
                int counts=sc.nextInt();
                store.setBrands(name);
                store.setSize(size);
                store.setPrice(price);
                store.setCounts(counts);
                store.setSid(id);
                String mes=storeController.update(store);
                System.out.println(mes);
            }
            public void del() {
                Store store=new Store();
                System.out.println("请输入要删除的商品id");
                int id=sc.nextInt();
                store.setSid(id);
                String mes=storeController.del(store);
                System.out.println(mes);
            }
    }

tools工具包

package com.oracle.tools;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Scanner;

public class Dbutil {
        private Dbutil() {}
        public static Connection getConn() {
            try{
                Class.forName("com.mysql.jdbc.Driver");
                String username="root";
                String password="123456";
                String url="jdbc:mysql://localhost:3306/demo_jdbc";
                Connection conn=DriverManager.getConnection(url,username,password);
                return conn;
                }catch(Exception ex){
                    throw new RuntimeException(ex+"数据库连接失败");
                }
        }
        public static void close(Statement sta,Connection conn) {
            if(sta!=null) {
                try {
                    sta.close();
                }catch(SQLException ex) {}
            }
            if(conn!=null) {
                try {
                    conn.close();
                }catch(SQLException ex) {}
            }
        }
        public static void close(ResultSet rs,Statement sta,Connection conn) {
            if(rs!=null) {
                try {
                    rs.close();            
                    }catch(SQLException ex) {}
            }
            close(sta,conn);
        }
        
}

service层

package com.oracle.service;

import java.util.ArrayList;

import com.oracle.dao.StoreDao;
import com.oracle.domain.Store;

public class StoreService {
            private StoreDao storeDao=new StoreDao();
            //查询
            public ArrayList<Store> find(){
                return storeDao.find();
            }
            //添加
            public int add(Store store) {
                return storeDao.add(store);
            }
            //修改
            public int update(Store store) {
                return storeDao.update(store);
            }
            public int del(    Store store) {
                return storeDao.del(store);
            }
}

controller层

package com.oracle.controller;

import java.util.ArrayList;

import com.oracle.domain.Store;
import com.oracle.service.StoreService;

public class StoreController {
        private StoreService storeService=new StoreService();
        public ArrayList<Store> find(){
            return storeService.find();
        }
        public String add(Store store) {
            int row=storeService.add(store);
            String mes=null;
            if(row!=0) {
                mes="添加商品成功";
            }else {
                mes="添加商品失败";
            }
            return mes;
        }
        public String update(Store store) {
            int row=storeService.update(store);
            String mes=null;
            if(row!=0) {
                mes="修改商品成功";
            }else {
                mes="修改商品失败";
            }
            return mes;
        }
        public String del(Store store) {
            int row=storeService.del(store);
            String mes=null;
            if(row!=0) {
                mes="删除商品成功";
            }else {
                mes="删除商品失败";
            }
            return mes;
        }
}

Dao层（Data Access Object）数据访问对象

package com.oracle.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;

import com.oracle.domain.Store;
import com.oracle.tools.Dbutil;

public class StoreDao {
    //查询
        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> list=new ArrayList<Store>();
                while(rs.next()) {
                    Store s=new Store();
                    s.setSid(rs.getInt("sid"));
                    s.setBrands(rs.getString("brands"));
                    s.setSize(rs.getDouble("size"));
                    s.setPrice(rs.getDouble("price"));
                    s.setCounts(rs.getInt("counts"));
                    list.add(s);
                }
                Dbutil.close(rs, sta, conn);
                return list;
            }catch(SQLException ex) {
            System.out.println(ex);
            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 pst=conn.prepareStatement(sql);
                pst.setString(1, store.getBrands());
                pst.setDouble(2, store.getSize());
                pst.setDouble(3, store.getPrice());
                pst.setInt(4, store.getCounts());
                int row=pst.executeUpdate();
                Dbutil.close(pst, conn);
                return row;
            }catch(SQLException ex) {
                System.out.println(ex);
                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 pst=conn.prepareStatement(sql);
                pst.setString(1, store.getBrands());
                pst.setDouble(2, store.getSize());
                pst.setDouble(3, store.getPrice());
                pst.setInt(4, store.getCounts());
                pst.setInt(5, store.getSid());
                int row=pst.executeUpdate();
                Dbutil.close(pst, conn);
                return row;
            }catch(SQLException ex){
                System.out.println(ex);
                throw new RuntimeException("商品修改失败");
            }
        }
        public int del(Store store) {
            try {
                Connection conn=Dbutil.getConn();
                String sql="delete from store where sid=?";
                PreparedStatement pst=conn.prepareStatement(sql);
                pst.setInt(1, store.getSid());
                int d=pst.executeUpdate();
                Dbutil.close(pst, conn);
                return d;
            }catch(SQLException ex) {
                System.out.println(ex);
                throw new RuntimeException("商品删除失败");
            }
        }
}

domain层

package com.oracle.domain;

public class Store {
    private int sid;
    private String brands;
    private double size;
    private double price;
    private int counts;
    public Store() {
        
    }
    public Store(int sid,String brands,double 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 double getSize() {
        return size;
    }
    public void setSize(double 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;
    }
}

测试类

package com.oracle.test;

import com.oracle.view.StoreView;

public class StoreApp {

    public static void main(String[] args) {
        new StoreView().run();
    }

}