2022-9-3 第一组 (≥▽≤) 学习笔记

目录

• 1.MVC架构
  • 使用关系
  • Model模型层
    • 实体类（entity）
    • 业务层（service）
    • 数据模型层（dao）
  • View层
  • Controller层
  • 工具类
    • 加密类
  • 所需的jar包

1.MVC架构

一种软件架构模式，把整个软件分为三层：

• Model模型——获取数据，并且返回给Controller
  • entity：——数据库的实体类
  • service（业务）：——业务控制层，【其余的活都交给service】
  • dao层（数据模型层）——操作数据库
• View视图——看见的页面，渲染数据，渲染页面
• Controller控制器——Servlet，接请求，给响应

耦合度：【代码之间的关联关系】。

为什么要分层？

• MVC
• 降耦合
• 重用性高
• 可维护性强

设计理念——一张表，一个entity，一个service，一个dao，一个controller

使用关系

View层发起请求——Controller——Service——Dao层——Service——Controller——View

Model模型层

实体类（entity）

实体类要求：

• 类名和表名相同
• 类中的属性和表中的字段名相同
• 类中只能有对应的set，get方法和需要用到的构造器，如果有需要，可以写toString
• 需要序列化，实现序列化接口

package com.gyc.morning.entity;

import java.io.Serializable;

public class Vip implements Serializable {
    private static final long serialVersionUID = -681512470754667710L;
    private Integer id;
    private String username;
    private String password;
    private String name;
    private String gender;
    private String profile;
    private String salt;

    public Vip() {
    }

    public Vip(String username, String password, String name, String gender) {
        this.username = username;
        this.password = password;
        this.name = name;
        this.gender = gender;
    }

    public Vip(Integer id, String username, String password, String name, String gender, String profile) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.name = name;
        this.gender = gender;
        this.profile = profile;
    }

    public String getSalt() {
        return salt;
    }

    public void setSalt(String salt) {
        this.salt = salt;
    }

    public static long getSerialVersionUID() {
        return serialVersionUID;
    }

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

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

    public String getPassword() {
        return password;
    }

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

    public String getName() {
        return name;
    }

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

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getProfile() {
        return profile;
    }

    public void setProfile(String profile) {
        this.profile = profile;
    }

    @Override
    public String toString() {
        return "Vip{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", profile='" + profile + '\'' +
                '}';
    }
}

业务层（service）

业务：软件的功能——例如：登录，注册

先创建接口

// 业务层
public interface VipService {
    // 注册的方法
    int register(Vip vip);
    // 登录
    Long login(String username,String password);
    // 根据用户名查询--盐
    String select(String username);

}

实现接口的类

public class VipServiceImpl implements VipService {
    private VipDao  vipDao=new VipDaoImpl();
    
    // 注册
    @Override
    public int register(Vip vip) {
        try {
            String salt = MD5Util.getSalt();
            vip.setPassword(MD5Util.stringToMD5(vip.getPassword()+salt));
            vip.setSalt(salt);
            return vipDao.save(vip);
        } catch (Exception e) {
            throw new RuntimeException();
        }

    }

    // 登录
    @Override
    public Long login(String username, String password) {
        try {
            password=MD5Util.stringToMD5(password+select(username));
            return vipDao.login(username,password);
        } catch (Exception e) {
            throw new RuntimeException();
        }
    }

    // 查询--盐
    @Override
    public String select(String username) {
        try {
            return vipDao.select(username);
        } catch (Exception e) {
            throw new RuntimeException();
        }
    }
}

数据模型层（dao）

• 执行SQL语句，获取数据

先创建接口

public interface VipDao {
    // 注册
    int save(Vip vip) throws Exception;
    
    // 登录
    Long login(String username,String password) throws Exception;
    
    // 添加
    String select(String username) throws Exception;
}

实现接口的类

public class VipDaoImpl extends DAOImpl<Vip> implements VipDao {
    @Override
    public int save(Vip vip) throws Exception {
        // 添加用户名,密码,性别,真实姓名,盐
        String sql="insert into vip(username,password,gender,name,salt) values(?,?,?,?,?)";
        return update(sql,vip.getUsername(),vip.getPassword(),vip.getGender(),vip.getName(),vip.getSalt());
    }

    @Override
    public Long login(String username, String password) throws Exception {
        // 根据用户名和密码查询是否存在
        String sql="select count(*) from vip where username=? and password=?";
        return  getForValue(sql,username,password);
    }

    @Override
    public String select(String username) throws Exception {
        // 根据用户名查询---盐
        String sql="select salt from vip where username=? ";
        return getForValue(sql,username);
    }
}

View层

前端页面，用来渲染实现页面的各种功能

代码实例

<!--index.html-->
<body>
<a href="login.html">登录</a>
<a href="register.html">注册</a>
</body>
<!--login.html-->
<body>
<form action="login.do" method="post">
    <p>账户: <input type="text" name="username"></p>
    <p>密码: <input type="password" name="password"></p>
    <input type="submit" value="登录">
</form>
</body>
<!--register.html-->
<body>
<form action="addVip.do" method="post">
    <p>账户:<input type="text" name="username"></p>
    <p>密码:<input type="password" name="password"></p>
    <p>姓名:<input type="text" name="name"></p>
    <p>
        性别:<input type="radio" name="gender" value="男">男
        <input type="radio" name="gender" value="女" checked>女
    </p>
    <p>
        <input type="submit" value="提交">
    </p>
</form>
</body>

Controller层

用来接受请求，发出响应

// 以.do结尾的所有请求路径
@WebServlet("*.do")
public class VipController extends HttpServlet {
    private VipService vipService = new VipServiceImpl();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 获取请求的根路径
        String servletPath = req.getServletPath();
        // 去掉请求根路径前边的/
        String substring = servletPath.substring(1);

        // 拿到.do前边的字符串
        substring = substring.substring(substring.lastIndexOf("/")+1, substring.length() - 3);


        try {
            // 拿到当前类要执行的方法的对象
            Method declaredMethod = getClass().getDeclaredMethod(substring, HttpServletRequest.class, HttpServletResponse.class);
            // 让方法去执行
            declaredMethod.invoke(this, req, resp);
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

    }

    private void addVip(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        String name = req.getParameter("name");
        String gender = req.getParameter("gender");
        Vip vip = new Vip(username, password, name, gender);
        vipService.register(vip);
    }

    private void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        Long login = vipService.login(username, password);
        // 如果为0,代表用户的账户密码不存在
        // 如果大于0,代表用户和密码存在
        if (login != 0) {
            System.out.println("Success");
        } else {
            System.out.println("Fail");
            resp.sendRedirect("login.html");
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

工具类

加密类

public class MD5Util {
    // MD5加密
    public static String stringToMD5(String str){

        return DigestUtils.md5Hex(str.getBytes());
    }
    
    // 创建盐
    public static String getSalt(){
        String words="qwertyuioplkjhgfdsazxcvb1234567890./;'[]-=`!@#$%";
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < 8; i++) {
            Random random = new Random();
            stringBuilder.append(words.charAt(random.nextInt(words.length()-1)));
        }
        return stringBuilder.toString();
    }
}

所需的jar包