MVC设计模式

最新推荐文章于 2022-11-01 19:06:02 发布

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最新推荐文章于 2022-11-01 19:06:02 发布

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分类专栏： javaWEB知识点

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MVC设计模式简单来说就是想我们的项目抽象层3个模块来进行设计项目架构，

M：模型层，模型层就是我们具体处理功能的java单元，例如dao，jdbc，service，utils。entity，这些统称javaBean
V：视图层，负责进行数据展示和用户进行数据交互，他之和控制层进行数据交互，和其他业务层不能有业务往来。例如jsp，html，jsf，ios，andorid
C：控制层，控制层负责协调视图层和业务逻辑层的关系。C负责吧视图层和模型串联起来。例如servlet、struts1、struts2，webwork，springmvc

，所以我们未来在设计代码的时候就一定要满足这个设计模式，这样可以让我们模块与模块之间形成高类聚，低耦合

我们mvc将项目分成3个模块化方案来编写，
同时我们在后台要对代码进行层次划分，一共分三层
1、控制层controller ：负责业务逻辑
2、服务层service：负责为业务逻辑提供额外服务
3、功能层dao ：负责具体的功能实现

所有写法必须按照接口定义功能，实现类实现具体操作的方式编写，未来我们就每次替换一层，然后逐步想框架进阶。
jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<%
    String path = request.getContextPath() + "/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>

    <form action="<%=path %>/servlet/AdminLogin" method="post">
        账号：<input type="text" name="account"><br>
        密码：<input type="password" name="pwd"><br>
        <input type="submit" value="登陆"/>
    </form>

</body>
</html>

servlet代码：

package com.xingxue.controller.admin;

import java.io.IOException;
import java.util.HashMap;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.xingxue.dao.AdminDao;
import com.xingxue.dao.impl.AdminDaoImpl;

/**
 * Servlet implementation class AdminLogin
 */
public class AdminLogin extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public AdminLogin() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String account = request.getParameter("account");
        String pwd = request.getParameter("pwd");
        HashMap<String, Object> param = new HashMap<String, Object>();
        param.put("account",account);
        param.put("pwd",pwd);

        AdminDao dao = new AdminDaoImpl();
        boolean isLogin = dao.adminLogin(param);

        System.out.println("===========" + isLogin);
    }

}

dao代码：

package com.xingxue.dao;

import java.util.HashMap;

/**
 * 用户操作
 * @author Administrator
 * 接口的方法都是public  abstract
 * 接口的属性都是public static final
 */
public interface AdminDao {

     int num = 10;

    /**
     * 用户登陆的方法
     * @param param  map包含账号和密码
     * @return 登陆成功或者失败
     */
    boolean adminLogin(HashMap<String, Object> param);

}

dao实现类代码：

package com.xingxue.dao.impl;

import java.sql.Connection;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;

import com.xingxue.dao.AdminDao;
import com.xingxue.utils.DBUtils;
import com.xingxue.utils.OracleDBUtils;

public class AdminDaoImpl implements AdminDao{

    QueryRunner runner = new QueryRunner();

    public boolean adminLogin(HashMap<String, Object> param) {
        boolean isFlag = false;
        Map<String, Object> result = new HashMap<String, Object>();
        String sql = "select * from admin where account=? and p = ?";
        Connection conn = OracleDBUtils.getConn();
        try {
            result = runner.query(conn, sql, new MapHandler(), param.get("account"),param.get("pwd"));
//          new MapListHandler()
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            OracleDBUtils.closeDB(conn, null, null);
        }
        return result.size() > 0;

    }
}

数据库工具类：

package com.xingxue.utils;



import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class OracleDBUtils {
    public static String url="jdbc:oracle:thin:@127.0.0.1:1521:orcl";
    public static String driver="oracle.jdbc.driver.OracleDriver";
    public static String user="scott";
    public static String pwd="tiger";

    public static void main(String[] args) {
        System.out.println(OracleDBUtils.getConn());
    }


    /**
     * 获取数据库链接
     * @return
     */
    public static Connection getConn() {
        Connection conn = null;
        try {
            //加载驱动
            Class.forName(driver);
            //获取链接
            conn = DriverManager.getConnection(url, user, pwd);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return conn;
    }


    /**
     * 关闭数据库资源
     * @param conn
     * @param pre
     * @param rs
     */
    public static void closeDB(Connection conn, Statement pre, ResultSet rs) {
        try {
            if(rs != null) {
                rs.close();
            }

            if(pre != null) {
                pre.close();
            }

            if(conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

service代码：服务层

package com.xingxue.service;

import java.util.HashMap;

public interface AdminService {

    boolean adminLogin(HashMap<String, Object> param);



}

package com.xingxue.service.impl;

import java.sql.SQLException;
import java.util.HashMap;

import com.xingxue.dao.AdminDao;
import com.xingxue.dao.impl.AdminDaoImpl;
import com.xingxue.service.AdminService;

public class AdminServiceImpl implements AdminService{

    AdminDao dao = new AdminDaoImpl();

    public boolean adminLogin(HashMap<String, Object> param) {

        return dao.adminLogin(param);

    }

}