项目开发简要流程

项目开发流程

1. 获取需求 (猪八戒网)
2. 设计
   数据库设计
   实体类设计(一般是实体类对应一张表)
   分层设计
   com.westos.eshop.controller (servlet) 控制层 + jsp
   com.westos.eshop.service (biz) 业务逻辑层
   com.westos.eshop.dao 数据访问层（完成数据的增删改查）
   com.westos.eshop.entity 实体类
   domain 域对象
   com.westos.eshop.util 工具类
3. 编写代码
4. 测试
5. 部署运行

例如：电商后台管理项目 中的实体类

1. 类别管理
   id（编号） name(名字) pid（父类别编号） lvl(级别)

package com.westos.eshop.entity;

import java.io.Serializable;

/**
 * 类别
 *
 * @author 寇祎欢
 */
public class Category implements Serializable {
    private int id;
    private String name;
    private int pid;
    private int sid;
    private String path;
    private int lvl;

    /**
     * 无参构造
     */
    public Category (){

    }

    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 int getPid() {
        return pid;
    }

    public void setPid(int pid) {
        this.pid = pid;
    }

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getPath() {
        return path;
    }

    public void setPath(String path) {
        this.path = path;
    }

    /**
     *
     * @return 返回
     */
    public int getLvl() {
        return lvl;
    }

    public void setLvl(int lvl) {
        this.lvl = lvl;
    }
}

2. 商品管理
   id（编号） jdzy_shop_id(店铺编号) brand_id（品牌编号） name（商品名称）
   origin_price 原始价
   market_price 市场价
   price 销售价
   img 图片地址
   category_id 类别编号

package com.westos.eshop.entity;

/*
id（编号） jdzy_shop_id(店铺编号) brand_id（品牌编号） name（商品名称）
origin_price 原始价
market_price 市场价
price 销售价
img 图片地址
category_id 类别编号
 */

import java.io.Serializable;

/**
 * 商品类
 * @author 寇祎欢
 */
public class Product implements Serializable {
    private int id;
    private int jdzy_shop_id;
    private  int brand_id;
    private String name;
    private int origin_price;
    private int market_price;
    private int price;
    private String img;
    private  int categor_id;

    /**
     * 无参构造
     */
    public Product(){

    }
    public int getId() {
        return id;
    }

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

    public int getJdzy_shop_id() {
        return jdzy_shop_id;
    }

    public void setJdzy_shop_id(int jdzy_shop_id) {
        this.jdzy_shop_id = jdzy_shop_id;
    }

    public int getBrand_id() {
        return brand_id;
    }

    public void setBrand_id(int brand_id) {
        this.brand_id = brand_id;
    }

    public String getName() {
        return name;
    }

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

    public int getOrigin_price() {
        return origin_price;
    }

    public void setOrigin_price(int origin_price) {
        this.origin_price = origin_price;
    }

    public int getMarket_price() {
        return market_price;
    }

    public void setMarket_price(int market_price) {
        this.market_price = market_price;
    }

    public int getPrice() {
        return price;
    }

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

    public String getImg() {
        return img;
    }

    public void setImg(String img) {
        this.img = img;
    }

    public int getCategor_id() {
        return categor_id;
    }

    public void setCategor_id(int categor_id) {
        this.categor_id = categor_id;
    }
}

3. 用户表
   username
   password

package com.westos.eshop.entity;

import java.io.Serializable;

/**
 * 用户类
 * @author 寇祎欢
 */
public class User implements Serializable {
    private String username;
    private String password;

    /**
     * 无参构造
     */
    public User(){

    }

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

    /**
     * 获取用户名
     * @return返回用户名
     */
    public String getUsername() {
        return username;
    }

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

    /**
     * 获取密码
     * @return返回密码
     */
    public String getPassword() {
        return password;
    }

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

问题及难点：
不输入条件
where name like ?
where price between ? and ?
where name like ? and (price between ? and ?)

public static List<Product> test (String name, Double lowPrice, Double highPrice, int m, int n) {
        StringBuilder sql = new StringBuilder(256);
        List<Object> values = new ArrayList<>();
        sql.append("select * from product where 1=1");
        if(name != null && !name.equals("")) {
            sql.append(" and name like ?");
            values.add(name);
        }
        if(lowPrice != null && highPrice !=null) {
            sql.append(" and price between ? and ?");
            values.add(lowPrice);
            values.add(highPrice);
        }
        sql.append(" limit ?, ?");
        values.add(m);
        values.add(n);
        System.out.println(sql);

        Connection conn = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;
        try{
            conn = Utils.getConnection();
            stmt = conn.prepareStatement(sql.toString());
            for (int i = 0; i < values.size(); i++) {
                stmt.setObject(i+1, values.get(i));
            }
            rs = stmt.executeQuery();
            List<Product> list = new ArrayList<>();
            while(rs.next()) {
                Product p = new Product();
                list.add(p);
            }
            return list;
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            Utils.close(rs, stmt, conn);
        }
    }