2021-07-24-有解無憂

mvc三層架構

最直觀的理解

MVC三層架構
M 業務資料層 DataBase 后廚
V 視圖層 jsp js html 迎賓
C 控制層 servlet 老板娘

下面我用實體模擬mvc三層架構的實作

控制層：

package com.orcl.servlet;
import com.orcl.service.IUserService;
import com.orcl.service.UserServiceimpl;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import java.io.IOException;
import java.util.List;
import java.util.Map;
@WebServlet("/testServlet")//id 用前端訪問后臺
public class TestServlet extends HttpServlet {
    //    創建一個用戶的服務
    IUserService userService = new UserServiceimpl();

    @Override
    public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        String username = request.getParameter("userName");//接到前端key值
        String password = request.getParameter("passWord");//接到前端key值
//呼叫modle層進行處理
        List<Map<String, Object>> list = userService.loginCheck(username, password);
        if (list.size() == 0) {
            //跳轉到錯誤頁面
            request.getRequestDispatcher("error.jsp").forward(request, response);
        } else {

            //跳轉到登錄成功頁面
            request.getRequestDispatcher("success.jsp").forward(request, response);
        }
    }
}

視圖層：

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
        <title>用戶登錄</title>

  </head>
  <br>
  <form action="testServlet" method="post">
        用戶名:<input type="text" name="userName" />  </br></br>
        密碼:<input type="password" name="passWord"  /> </br></br>
       <input type="submit" value="登錄">
  </form>
  </body>
</html>

success.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
        <title>登錄成功</title>

  </head>
  <br>
  <body>
  登陸成功
  </body>
</html>

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
        <title>登陸失敗</title>

  </head>
  <br>
  <body>
  登錄失敗
  </body>
</html>

業務資料層：

package com.orcl.service;

import com.orcl.dao.DaoImpl;
import com.orcl.dao.IDao;

import java.io.IOException;
import java.sql.SQLException;
import java.sql.Types;
import java.util.List;
import java.util.Map;

public class UserServiceimpl implements IUserService {
    IDao dao=new DaoImpl();
    @Override
    public List<Map<String, Object>> loginCheck(String userName, String passWord) {
        String sql="select * from student where name=? and password=? ";
        int[] types=new int[]{Types.VARCHAR,Types.VARCHAR};
        Object []values=new Object[]{userName,passWord};
        List<Map<String,Object>> list=null;
        try {
           list=dao.executeQueryForList(sql,types,values);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return  list;
    }
}

如圖已經搭建好三層架構我鏈接的mysql資料庫